The Encyclopedia Of Nutrition And Good Health - S pdf

saccharin One of the oldest
ARTIFICIAL SWEETEN-
ERS, saccharin has been available for more than 100
years. It is not metabolized in humans and it pro-
vides no calories. Although saccharin is 300 to 700
times sweeter than
TABLE SUGAR, it is often per-
ceived to have a bitter or “metallic” aftertaste at
high concentrations. Saccharin is generally com-
bined with a sugar,
DEXTROSE, or with ASPARTAME,
another artificial sweetener, for tabletop sweeten-
ers. The compound is stable to baking and acidic
conditions; this versatility contributes to its use in
many products, including baked foods, salad dress-
ings, reduced calorie jams, toothpaste, mouthwash,
and other personal care products. Saccharin can be
added to chewing gum where it is used with
SOR-
BITOL, a sweet sugar analog.
In May 2000 officials at the National Institute of
Environmental Health Sciences and its subdivision,
the National Toxicology Program, announced that
saccharin would no longer appear on their list of
“cancer threats.” Saccharin had officially been
listed as a carcinogen in March 1977 when Cana-
dian researchers discovered a link between saccha-
rin and bladder tumors in male rats. This finding
immediately triggered the threat of the
DELANEY
CLAUSE

, a congressionally mandated provision that
requires the U.S. Food and Drug Administration to
ban any synthetic food chemical shown to cause
cancer when ingested by laboratory animals. When
millions of dieting Americans heard that the only
low-calorie sweetener available was going to be
banned (cyclamates had been banned in 1970 for
similar reasons), they were upset; Congress
responded by protecting saccharin from the
Delaney Clause by allowing it back on the market
with a health warning label. Saccharin’s chances
were further damaged in 1981 when the National
Toxicology Program, referring again to the Cana-
dian rat study, decided to put saccharin on its “can-
cer causing” list—formally declaring it an “antici-
pated human carcinogen.”
In September 1996 the Calorie Control Council,
a trade group of the diet food industry, petitioned
the toxicology program to have saccharin reclassi-
fied. Subsequently, two government scientific pan-
els that looked at the possible link between
saccharin and cancer supported removal, saying
that any link to cancer was weak. A third scientific
panel of nongovernment experts voted 4–3 against
taking saccharin off the list.
Nevertheless, in December 2000 Congress passed
the Saccharin Warning Elimination via Environ-
mental Testing Employing Science and Technology
Act (“SWEETEST Act”) after a National Toxicology
Program review concluded that saccharin poses no

health hazard to humans. The report concluded
that the observed bladder tumors in rats were
caused by mechanisms not relevant to humans and
that no data in humans suggest that a carcinogenic
hazard exists. The legislation allowed manufactur-
ers to remove the warning labels from saccharin
packages that said the sweetener had been shown
to cause cancer in lab animals. (See also
FOOD ADDI-
TIVES
; NATURAL SWEETENERS.)
S-adenosylmethionine (SAMe) A synthetic form
of the
AMINO ACID METHIONINE, S-adenosylmethion-
ine is found in every cell in the human body.
SAMe has been used in Europe since the 1960s as
a prescription antidepressant and pain reliever and
was introduced to the U.S. market in 1999 as a
dietary supplement.
In the body SAMe normally maintains cell
membranes and is involved in methylation, a
process that, among other things, helps to regulate
levels of the mood-lifting neurotransmitters sero-
S
565
tonin and dopamine. Some study subjects have
reported that SAMe is effective as an antidepres-
sant. Several clinical studies have demonstrated
that SAMe is better than placebo and is equivalent
to nonsteroidal anti-inflammatory drugs (NSAIDS)

such as ibuprofen for easing pain associated with
osteoarthritis. Patients suffering from fibromyalgia
have also reported significant relief from the symp-
toms that accompany that disease. SAMe has also
shown some promise in treating patients who suf-
fer liver diseases such as cirrhosis (liver failure)
caused by alcohol abuse.
Because SAMe was introduced in the United
States as a dietary supplement, it has not under-
gone review by the U.S.
FDA for safety or efficacy,
and many scientists and others in the medical com-
munity have expressed skepticism regarding its
reported health benefits. These critics say the study
subjects may have been reporting
PLACEBO effects
and that all the studies that have been done so far
were for periods of time that were too short to pro-
duce statistically significant results. Additional
studies are ongoing. Safety data are inadequate for
pregnant and breast-feeding women.
Soekin, A. L. “Abstract: Safety and Efficacy of S-adeno-
sylmethionine (SAMe) for Osteoarthritis,” Journal of
Family Practice 51, no. 5 (2002): 425–430.
safflower (Carthamus tinctorius) A thistle-like
plant that produces oil-rich seeds resembling small
sunflower seeds. Safflower is a late arrival in the
United States, becoming an established crop only
in the 1950s and 1960s as
POLYUNSATURATED VEG-

ETABLE OILS
gained in popularity in response to
fears about
CHOLESTEROL and SATURATED FAT and
their link to
ATHEROSCLEROSIS. Varieties of saf-
flower yielding 50 percent oil have been devel-
oped. Safflower is cultivated in California and
Montana.
Safflower oil contains the highest percentage of
polyunsaturated
FATTY ACIDS and the lowest per-
centage of saturated fatty acids among commer-
cially available oils. Typically, safflower oil contains
74 percent to 77 percent
LINOLEIC ACID, an essential
polyunsaturated fatty acid; 16.4 percent
OLEIC ACID,
a monounsaturated fatty acid; and 6.6 percent sat-
urated fatty acids. Like
SOYBEAN oil, it has a high
smoke point (440° to 480° F) and is often used in
deep-fat frying and sauteeing. Safflower oil is rich
in
VITAMIN E. As a polyunsaturated oil, it is suscep-
tible to
RANCIDITY (decomposition) when heated.
These oils should not be reheated.
Like all commercial polyunsaturated cooking
oils, safflower is partially hydrogenated to reduce

its susceptibility to oxidation and decrease the rate
of rancidity. Hydrogenation refers to the chemical
hardening process that adds hydrogen atoms and
decreases the level of saturation. Hydrogenated
safflower oil yields
MARGARINE, VEGETABLE SHORTEN
-
ING, MAYONNAISE, and other products. Hydrogena-
tion creates
TRANSFATTY ACIDS. The safety of these
unusual products has been questioned.
The consumption of polyunsaturated vegetable
oils like safflower oil can lower the level of
LOW-
DENSITY LIPOPROTEIN (LDL), the less desirable form
of cholesterol, but at the same time a high intake
can lower the level of
HIGH-DENSITY LIPOPROTEIN
(HDL), the desirable form of cholesterol. (See also
ESSENTIAL FATTY ACIDS.)
saffron (Crocus sativus) This small crocus pro-
duces flowers with intense yellow-orange fila-
ments. When dried, the stamens yield a pungent
spice and brilliant yellow coloring agent. Saffron
is used for rice dishes, soup, and sauces, as well
as certain meat dishes in Indian, Italian, and Span-
ish cuisine. Saffron is best dissolved in a small
amount of warm water before use for uniform
mixing. (See also
FOOD ADDITIVES;

FOOD COLORING,
NATURAL.)
sage (Salvia officinalis) A common perennial
HERB whose fresh or dried leaves add a pungent,
bitter taste to foods. There are over 500 varieties of
sage, including the common garden sage. It is used
to flavor poultry, fatty meat like pork, veal, ham, or
lamb, and in marinades, minestrone, and sauces.
Sage has long been used as a medicinal herb in folk
medicine. Its name comes from the Latin salvus,
which means healthy. It possesses bacterial and
antifungal properties and it has been used to aid
digestion. Sage tea has been used to reduce cough-
ing associated with colds and for irregular men-
struation. As with any medicinal herb, the
consumption of large amounts for long periods of
time is not recommended. (See also
PARSLEY.)
566 safflower
sago Starch from the trunk of a tropical palm. In
the South Pacific, sago palm flour and starch are
staple foods. They are used as food thickeners.
Commercially, sago starch is used as a noncorn
source of glucose from which to manufacture corn-
free
VITAMIN C for certain individuals who are ultra-
sensitive to corn products. (See also
OIL PALM; PALM
OILS
.)

salami A deli sausage usually made from
PORK
or a combination of pork and BEEF and several
seasonings, including salt, garlic, black pepper,
and fennel. Salami is a high-fat (generally 30 per-
cent) and high-sodium food. Some, but not all,
salamis are cured and may contain preservatives
such as nitrites. Several varieties are available,
including cacciatore, pepperoni, and genoa.
Salami is usually sliced thin for use in sandwiches
or, in the case of pepperoni, on pizza. One slice of
cooked salami (23 g) yields 57.5 calories; fat, 4.5
g; protein, 3 g; potassium, 45.5 mg; sodium 245
mg.
saliva The fluid secreted by glands of the MOUTH.
Three pairs of salivary glands produce saliva.
Parotid glands, located on each side of the face,
drain through ducts opening in the inner surface of
the cheek. Sublingual glands drain into the floor of
the mouth. Submaxillary glands (submandibular
glands) are located beneath the base of the tongue
and drain in the floor of the mouth. Tiny buccal
glands in the mouth also contribute saliva. The
combined saliva from all these sources amounts to
a quart (1 liter) of fluid daily.
In composition, saliva is 99.5 percent water.
Saliva serves important functions: It acts as a lubri-
cant, as a moistening agent and as a dissolving
agent for flavors as food is chewed and swallowed.
Saliva contains mucins, slippery

PROTEINS that pro-
vide the lubricating action. Without water and
mucins, swallowing would be very difficult. Saliva
contains the digestive enzyme
AMYLASE, which ini-
tiates starch
DIGESTION, and chewing food thor-
oughly to a uniform paste assists starch breakdown
by this enzyme. Saliva also contains ions (elec-
trolytes)—
SODIUM, CHLORIDE, and BICARBONATE.
Chloride activates amylase. These minerals are
later absorbed and recycled. For defense, saliva
contains lysozyme, an enzyme that ruptures some
disease-producing bacteria, and a protective
ANTI-
BODY, secretory IgA, that can bind to foreign mate-
rials, including viruses, bacteria, and yeast, to
reduce this risk of infection.
Salivation is controlled exclusively by the
NER-
VOUS SYSTEM. Savory aromas, visual images, sounds
of food preparation, and memories can stimulate
salivation. Salivation also occurs in response to irri-
tating foods and with nausea. Saliva flow after eat-
ing flushes chemical remnants out of the mouth
and adjusts the acidity to neutral. Dehydration can
decrease salivation. A variety of medications, such
as antihistamines (diphenylpyraline and azatidine),
diminish mucous secretions, including saliva.

Stress stimulates the sympathetic nervous system
to reduce salivation. On the other hand, dryness of
the mouth promotes thirst sensations. (See also
DEGLUTITION; TASTE.)
salmon (Oncorhynchus) A saltwater fish valued
as a food fish, and as a sport fish. The word salmon
is derived from the Latin salmo, which means “leap-
ing.” Salmon can weigh up to 65 lb. and measure
up to 3 ft. long. Varieties include the Atlantic
salmon and the five varieties of Pacific salmon:
sockeye (red) salmon (O. nerka), both canned and
sold fresh; Chinook (king) salmon (O. tschawytscha),
the largest and fattiest variety; coho (sliver) salmon
(O. kisutch), smaller fish, sold fresh; pink (hump-
back) salmon (O. gorbuscha), the smallest variety,
bland flesh, sold canned; and chum (dog) salmon
(O. keta), lower in fat and with pale flesh. Salmon
are a migratory fish that spawn in fresh water.
Young fish live in fresh water for two years before
migrating to the sea. Pollution, dam construction,
and overharvesting have drastically reduced the
numbers of this food fish in many parts of the
world. Commercial salmon comes from many
countries, such as Chile, Norway, and Canada
(eastern Canada and British Columbia). Imported
salmon are generally pen-raised rather than wild
fish. Domestic, pen-raised salmon are also readily
available. In the United States, Maine, Alaska, and
Washington support most major salmon fisheries,
and canned salmon comes from the northern

Pacific. Most Atlantic salmon comes from Canada
and Norway.
salmon 567
Salmon is an oily fish, rich in beneficial marine
lipids. Salmon fat contains 30 percent to 40 percent
omega-3 polyunsaturated
FATTY ACIDS, mainly EPA
(
EICOSAPENTAENOIC ACID) and DHA (DOCASAHEXA-
ENOIC ACID
). These polyunsaturates are believed to
decrease the risk of
STROKE and CARDIOVASCULAR
DISEASE
. They decrease the risk of blood clots by
inhibiting blood platelet aggregation. Platelets are
cell fragments in the blood that initiate clotting.
Pen-raised salmon are more likely to be conta-
minated with industrial pollutants when grown in
waters near industrial areas. Consumer advocates
have criticized seafood safety in the United States.
PCB contamination has been detected in fresh
salmon although the levels were below tolerance
limits set by the U.S.
FDA. Canned salmon sold in
the United States comes from the Pacific off the
coast of Alaska, an area less likely to be polluted by
industrial waste. Salmon is smoked, poached,
grilled, marinated, baked, or canned. The nutrient
content of 3 oz. (85 g) of broiled salmon is: 140

calories; protein, 21 g; fat, 5 g; cholesterol, 60 mg;
thiamin, 0.18 mg; riboflavin, 0.14 mg; niacin, 5.5 g.
(See also
FISH OIL; OMEGA-3 FATTY ACIDS; SEAFOOD.)
salmonella A bacterium that includes more than
1,300 strains that frequently causes
FOOD POISON-
ING. Salmonella does not form spores and is
destroyed by heat. Its usual habitat is the intestinal
tract of an animal host. Salmonella occurs in ani-
mal feed, food processing plants, and food han-
dling, and the bacteria are easily spread by fecal
contamination. Flies, rodents, and insects that con-
tact infected fecal material may also contaminate
food. Sewage-contaminated water is known to
carry salmonella and cause disease.
Livestock and poultry are major sources of
human infection. About one in 20,000 eggs is con-
taminated. Thoroughly cooking eggs destroys the
bacteria. According to the U.S. Centers for Disease
Control and Prevention, most cases of salmonella
poisoning are caused by eating undercooked eggs
in sauces, salads, and processed foods. Salmonella
grows readily in milk and milk-derived dishes such
as custard, egg dishes, and salad dressing.
MEAT and
meat products like
SAUSAGE, meat pies, sandwiches,
and chili can become contaminated when allowed
to stand at room temperature for several hours if

infected by a food handler.
salmonellosis A form of food poisoning caused
by salmonella. Salmonellosis is one of the three
most common food-borne diseases associated with
bacteria, and it is one of the fastest growing food-
borne illnesses. Every year about 40,000 cases of
salmonellosis are reported in the United States. The
actual number of cases may be much higher
because many people who have been infected do
not seek professional care and are therefore not
diagnosed and reported. Illness caused by salmo-
nella is more common during the summer months,
and children are more likely to be infected. Salmo-
nellosis can be fatal, especially in young children,
the immunocompromised, and elderly people.
About 1,000 persons die each year from acute sal-
monellosis. Some strains of salmonella resist antibi-
otics, and dairy cattle fed antibiotics were the likely
source of a drug-resistant salmonella strain that
caused a large U.S. outbreak of food poisoning,
involved six states in 1985. This outbreak caused
1,000 deaths, 35,000 hospitalizations and left an
estimated 125,000 people with increased risk of
chronic illnesses such as
ARTHRITIS, osteomyelitis,
ankylosing spondylitis, and
COLITIS.
Salmonellosis often causes flu-like symptoms.
Fever, abdominal cramping, headache,
DIARRHEA

,
and vomiting generally appear 12 to 36 hours after
eating tainted food. Symptoms may last from two
days to a week. Illness is most severe in those with
weakened immune systems, commonly found in
very young children and in elderly people.
Maldigestion and
MALABSORPTION can result from
intestinal damage due to this disease.
Salmonellosis was almost unknown in the
United States 40 years ago. Increased volume and
speed of food production, increased drug resistance
of bacteria, and relaxed enforcement by govern-
ment agencies contributed to widespread contami-
nation of food, especially
POULTRY. Raw milk, raw
cheese, any raw or undercooked meat, including
salami and hamburger, and fresh eggs can be cont-
aminated by feces and fecal bacteria and can thus
be a potential source of contamination. Pasteurized
eggs are used to prepare commercial
MAYONNAISE,
and it is not a carrier. Freshwater as well as marine
fish caught from waters highly polluted by raw
sewage may be contaminated by salmonella.
All food handlers should thoroughly wash their
hands before handling food to eliminate fecal con-
568 salmonella
tamination. They should carefully clean all equip-
ment used in food preparation, including cutting

boards. Raw vegetables should not come into con-
tact with utensils used to prepare raw meat and
poultry. Food should be refrigerated. Salmonella is
destroyed by heating at 140° F (60° C) for 20 min-
utes or at 149° F (60° C) for three minutes. (See
also
BOTULISM.)
Olsen, S. J. et al. “The Changing Epidemiology of Salmo-
nella: Trends in Serotypes Isolated from Humans in
the U.S., 1987–1997,” Journal of Infectious Diseases 183
(2000): 756–761.
salt See SODIUM.
salt substitutes (potassium chloride, lite salt, low-
sodium salt) A combination of chemicals that
taste like table salt but contains less
SODIUM. Exces-
sive salt in the diet can cause
HIGH BLOOD PRESSURE
in hypertensive people who are sodium sensitive.
Most salt substitutes are mixtures of table salt
(sodium chloride) and
POTASSIUM chloride. Potas-
sium is an essential nutrient in its own right and
can lower blood pressure in some people. Excessive
potassium can irritate the stomach and might start
an ulcer. Diseased or damaged kidneys may not be
able to excrete potassium properly; a toxic excess
can accumulate. Therefore, patients taking certain
DIURETICS (water pills), beta blockers or non-
steroidal anti-inflammatory drugs; who are dia-

betic; or who have kidney disease are advised to
avoid such salt substitutes. The safest strategy is to
cut back on salt entirely and to use herbs and spices
to improve the flavor in place of table salt. There
are many different herbs to choose from, each with
its own different, pleasing flavor. Consider
CAYENNE
pepper, basil, garlic powder, mace, marjoram,
SAGE,
savory and thyme, or blends. (See also
FOOD ADDI-
TIVES; HYPERTENSION.)
salt tablets See SODIUM.
SAMe See S-ADENOSYLMETHIONINE.
sardine Various small saltwater fish, including
alewife, Atlantic
HERRING, pilchard, and sprat. The
name probably originated from the small Mediter-
ranean fish in the vicinity of the island of Sardinia.
Sardines are a fatty fish. Atlantic herring is a good
source of
OMEGA-3 FATTY ACIDS, the essential fatty
acids thought to protect against heart attacks.
Sardines are rich sources of calcium because the
fish is cooked bones and all. Its soft bones con-
tribute to a high calcium content. A 4 oz. serving of
sardines provides 50 percent of the
REFERENCE DAILY
INTAKE
(RDI) of calcium and 20 percent of the RDI

or iron. Sardines contain significant levels of salt.
The same 4 oz. serving provides approximately 600
mg of sodium, one-third to one-half of the amount
judged safe.
Sardines are often packed in oil, which increases
their calories. Sardines packed in olive oil would be
preferable to those packed in soybean oil because
of olive oil’s greater stability and protective effects
against heart disease. Norwegian sardines are often
packed in sardine oil, which has a high content of
omega-3 fatty acids. Blot the fish in oil with a paper
towel before eating them, to remove excess oil and
to lower calories. Sardines packed in water are now
available. The nutrient content of 3 oz. (85 g) of
sardines (canned, packed in soybean oil, drained,
and including bones) is: 175 calories; protein, 20 g;
fat, 9.4 g; cholesterol, 85 mg; calcium, 371 mg;
iron, 2.6 mg; thiamin, 0.03 mg; riboflavin, 0.17 mg;
niacin, 4.6 mg.
sarsaparilla (Smilax sarsaparilla) A medicinal
herb native to tropical regions of South America
and the Caribbean. This perennial evergreen grows
as a vine; its roots are used in botanical medicine.
Europeans learned of its use from Native Ameri-
cans. According to folk traditions, sarsaparilla has
been used as a tonic (to improve body function)
and in the treatment of coughs, digestive disorders,
fever, gout, skin conditions, and arthritis. Exter-
nally it has been used for burns and wounds. No
toxicity has been reported, though the effects of

long-term, high-level consumption are unknown.
Sarsaparilla contains a family of saponins,
steroid-like molecules that appear to bind cell wall
materials released by bacteria in the intestine.
Endotoxins can be absorbed by the gut and pass
into the bloodstream unless removed by the liver.
By rendering endotoxins unabsorbable, sarsaparilla
may improve liver function and decrease the bur-
den of foreign materials. The plant does not contain
sarsaparilla 569
testosterone, the male hormone, and does not
increase muscle mass. Thus, there is little evidence
to support the contention that sarsaparilla acts as a
sexual rejuvenator. Sarsaparilla extracts have been
routinely used to flavor beverages, candy, baked
goods, and other foods.
satiety The sense of being filled up and having
APPETITE satisfied, as opposed to HUNGER. Appetite is
a complex phenomenon involving many psycho-
logical and biochemical factors. No single event is
likely to control it. Fat and oils in foods slow emp-
tying of the stomach and contribute to the feeling
of being full. Researchers are exploring the hypoth-
esis that depleted fat cells may signal the brain to
eat and cause hunger after weight loss.
LEPTIN,a
recently discovered protein produced by fat cells,
has been shown to enter the brain and control the
consumption of fatty foods. Dietary
FIBER, undi-

gestible plant material, swells when moistened,
creating a feeling of fullness. As a further benefit,
fiber displaces calorie-rich foods, so fewer calories
are eaten.
Mechanical contact with food triggers the stom-
ach and intestine to release gut peptides that trigger
satiety. This feedback mechanism requires 10 to 20
minutes, while signals are being sent back to the
brain. As an example, the hormone
CHOLECYS
-
TOKININ signals the brain to stop sending hunger sig-
nals after eating. Whether cholecystokinin can be
manipulated by dietary changes is not known for
certain. Brain peptides are also probably involved in
regulatory food consumption and satiety. Entero-
statin decreases fat intake in experimental animals.
The development of drugs to increase satiety is cur-
rently an area of active research. Strategies to pro-
mote a feeling of satiation and to curb appetite
include eating a snack a half-hour before a meal,
eating slowly and chewing each bite thoroughly
and waiting 20 minutes before taking a second
helping. These approaches give the hormone time
to reach the brain and create a feeling of fullness.
(See also
APPETITE SUPPRESSANTS; CRAVING.)
saturated fat FAT that contains a high percentage
of saturated
FATTY ACIDS and exists as a solid at

room temperature. Saturation is a chemical con-
cept, referring to the fact that carbon atoms in the
fatty acid molecules are bonded to a maximum
number of hydrogen atoms (“filled up”). Typical
sources of saturated fat are animal fat, as found in
BEEF
, veal, LAMB, PORK, meat products, MILK, EGGS,
BUTTER, and products like ICE CREAM, milk, and
CHOCOLATE
. Certain plant oils are also saturated,
including
COCONUT OIL, PALM, and palm kernel oils.
Unsaturated fat (vegetable oils) can be converted to
saturated fats by a chemical process called hydro-
genation, and these appear on the market as veg-
etable shortening.
Saturated Fatty Acids
Common building blocks of fats and oils, these
organic acids contain a maximum number of
hydrogen atoms and lack double bonds. Fatty acids
are built of carbon chains, which may be long or
short. Long-chain, saturated fatty acids include
PALMITIC ACID (16 carbon atoms) and STEARIC ACID
(18 carbon atoms). They are waxy solids at room
temperature and can form fats that are also solids at
room temperature. Typical short-chain saturated
fatty acids include: acetic acid (containing two car-
bon atoms), propionic acid (with three carbon
atoms), and
BUTYRIC ACID (four carbon atoms).

Medium-chain fatty acids include
CAPRYLIC ACID
(with eight carbons); capric acid (10 carbons); lau-
ric acid (12 carbons); and myristic acid (14 carbons).
All saturated fatty acids are readily oxidized by
mitochondrial enzyme systems to produce energy
with carbon dioxide and water as waste products.
Fatty acids yield more than twice the amount of
energy as carbohydrate and protein when they are
burned. (See also
ESSENTIAL FATTY ACIDS.)
saturated vegetable oils See
TROPICAL OILS.
sauce A flavorful relish or liquid dressing served
with foods. Sauces are usually high-
FAT foods.
Stroganoff and orloff usually contain butter. Hol-
landaise and bearnaise sauces contain butter and
egg yolks; bearnaise contains undercooked raw egg
yolk and so is a potential source of food poisoning.
MAYONNAISE contains egg yolks, VINEGAR, and a veg-
etable oil. Brown sauces (bordelaise and bour-
guignon) may be lower in fat if fat has been
skimmed off and if butter has not been added. Tar-
tar sauce and remoulade are flavored mayonnaise.
570 satiety
sauerkraut Fermented white CABBAGE. Cabbage
is pickled in salt, spices, and cabbage juice by lactic
acid-producing bacteria. The lactic acid gives sauer-
kraut its characteristic sour flavor. Canned sauer-

kraut also has a very high sodium level (up to 780
mg per half-cup). It can be strained and rinsed to
decrease the sodium content. Dill seed and onion
can be used to enhance the flavor of sauerkraut.
(See also
FERMENTATION; FOOD PRESERVATION
.)
sausage A seasoned, ground meat product usu-
ally containing high levels of
SODIUM and FAT and
packed in a casing. The term sausage is derived from
the Latin salsicius, meaning “seasoned with salt.”
Most sausage contains highly seasoned, finely
ground beef and pork and table salt. Any meat from
a USDA-inspected carcass can be used to make
sausage and animal fat can be added. Thus, blood
sausage is made from blood, pork fat, and season-
ing. The final product may be cured (smoked) and
dry or semidry. Dry and semidry sausage may con-
tain
NITRITES as preservatives, which have been
linked to an increased risk of stomach cancer if con-
sumed in large amounts. Fresh sausage is made
from raw meat and must be cooked. Semidry
sausage has been smoked; dry sausage may or may
not be smoked; and cooked sausage is ready to eat.
Examples include
BOLOGNA, braunschweiger, frank-
furter, head cheese, knackwurst,
LIVERWURST,

salami, souse, and Vienna sausage.
Sausages contain ample protein, iron, and many
B vitamins; however, they also contain almost 55
percent of their calories as fat. A few brands con-
tain less than 40 percent of their calories as fat.
Tofu and turkey sausage may contain less fat than
pork or beef products. It is recommended that
sausage be eaten as a condiment or flavoring with
foods rather than as a main dish.
Pork sausage, cooked, can provide 72 percent of
calories as fat; fat accounts for 31 percent of the
weight. One link, 13 g, provides 50 calories; pro-
tein, 2.5 g; carbohydrate, 0.1 g; fat, 4 g; cholesterol,
11 mg; sodium, 168 mg; thiamin, 0.1 mg; ribo-
flavin, 0.03 mg; niacin, 0.59 mg. (See also
CHICKEN;
MEAT, PROCESSED; MEAT SUBSTITUTES; POULTRY.)
sauté Refers to pan frying small strips or slices of
food quickly in a hot skillet with a small amount of
butter or oil. Be sure oil is hot before adding foods
to minimize the amounts of oil they soak up. Pork
slices, veal scallops, chicken breast, fish fillet, tofu,
onions, carrots, garlic, and other vegetables and
grains can be sauteed.
saw palmetto (Serenoa repens) A small palm
tree native to South Carolina, Georgia, and Florida
that produces berries with medicinal properties.
Saw palmetto berries have a long history of use by
Native Americans, while later European physicians
used the berries to treat enlarged prostate (benign

prostatic hyperplasia), genitourinary tract imbal-
ances, and as a tonic to boost nutrient and general
body functioning. Modern formulations employ a
fat-soluble extract of saw palmetto berries contain-
ing large-molecular-weight alcohols and plant
sterols, compounds related to cholesterol. Saw pal-
metto berry extracts block the conversion of the
male sex hormone, testosterone, to a more potent
compound, dehydrotesterone, that promotes pro-
static enlargement, and promote the breakdown of
the more active compound. These effects may pos-
sibly explain the saw palmetto relief of common
symptoms such as decreased urination at night,
increased urinary flow rates, and decreased resid-
ual urine content in the bladder. No significant side
effects of saw palmetto berry extracts or berries
have been noted.
School Breakfast Program A federal program to
provide funds for nutritious breakfasts for chil-
dren. The National School Breakfast Program was
established by the Child Nutrition Act of 1966 an
authorized as a permanent appropriation in 1975.
Fewer children participate in the
BREAKFAST pro-
gram than in the
SCHOOL LUNCH PROGRAM. In the
1999–2000 school year 7.6 million children partic-
ipated in the breakfast program, while 27.4 million
children participated in the lunch program. Usu-
ally a state’s Department of Education administers

this program.
The school breakfast must contain one serving
of meat or meat alternative (such as eggs or peanut
butter), two or more servings of different fruits or
vegetables, and one serving of milk.
Factors weighed in planning school food service
programs include: cultural and ethnic backgrounds
School Breakfast Program 571
of students, needs of handicapped students, as well
as fitting meals to accommodate class and bus
schedules. Practical nutrition education can be part
of breakfast programs. Evaluation of school nutri-
tion programs finds that most students participat-
ing in school breakfast programs are from
low-income families.
Breakfast is considered the most important meal
for both children and adults because of its positive
impact on performance and alertness. Nonetheless,
many Americans skip breakfast, especially teen-
agers. Students who skip breakfast have higher
rates of tardiness, higher absenteeism and lower
performance, and more
FATIGUE
. Researchers
shows that low-income children who participate in
the School Breakfast Program have higher stan-
dardized achievement test scores than children not
in the program. (See also
HUNGER; WIC.)
School Lunch Program A federal program estab-

lished under the National School Lunch Program of
1946 to protect the health of U.S. children through
the consumption of nutritious foods. The act
authorized state grant-in-aid program to provide
cash and food. The cost is shared among the
USDA,
state and local governments, and children’s fami-
lies. Household income determines whether a child
will receive a reduced rate or free meal. To qualify,
household income must be below 185 percent of
the federal poverty level; for free meals household
income must fall below 130 percent of the poverty
level.
The National School Lunch Program is open to
public and private schools and to residential child
care institutions. Schools that participate in the
program receive financial assistance, donated sur-
plus commodities and technical assistance in
equipping and managing the program. In the
1970s, the Nutrition Education and Training Pro-
gram was developed to educate students about the
relationship between nutrition and health, to train
food service personnel in management, and to
instruct teachers in nutrition education. The pro-
gram was expanded due to increased need for
low-cost, subsidized meals, especially among eco-
nomically disadvantaged children.
On a typical day in school year 2000–2001, 15.6
million children participated in the program. The
program has continued to serve nutritious school

lunches to children who would not likely receive
lunch from another source. Furthermore, school
lunches have provided approximately 33 percent of
the
RECOMMENDED DIETARY ALLOWANCES (RDAs) for
children of various ages. Eligibility for participation
in the program is contingent upon operating on
a nonprofit basis, providing free or reduced
price lunches to needy children, making lunches
available to all children providing dining and
kitchen facilities, avoiding segregation of needy
children and serving meals that conform to USDA
guidelines.
School lunches must meet the
DIETARY GUIDE-
LINES FOR AMERICANS, which recommend that no
more than 30 percent of a person’s calories come
from fat and less than 10 percent from saturated
fat. The lunches should also provide one-third of
the U.S. RDA of protein, iron, calcium, and vita-
mins A and C. In 2001 the Physician’s Committee
for Responsible Medicine issued a report that found
that many school lunches offered in the National
School Lunch Program did not meet these require-
ments. Only one in 12 elementary school districts
substituted lower-fat, cholesterol-free plant protein
in place of meat, and one-fourth were not meeting
USDA nutrition requirements.
scromboid fish poisoning A type of FOOD POISON-
ING

that occurs within an hour after eating species
of spoiled fish that populate tropical oceans, includ-
ing
TUNA, MACKEREL, skipjack, BONITO, HERRING,
mahi-mahi,
SARDINES, and anchovies. An impor-
tant clue to contamination is that infected fish taste
metallic and peppery. Symptoms of poisoning in-
clude flushing, sweating, nausea, vomiting, diar-
rhea, headache, and dizziness. Antihistamines
relieve the symptoms. Scromboid fish poisoning
can be prevented by keeping fresh fish on ice
or refrigerated until it is cooked. (See also
FOOD
TOXINS
.)
scurvy A disease caused by severe deficiency of
VITAMIN C (ascorbic acid). Scurvy has been de-
scribed since ancient times. Long sea voyages of the
15th through the 17th centuries frequently deci-
mated the ranks of sailors. As early as 1593, a
British admiral demonstrated that lemon juice
572 School Lunch Program
cured the disease. A Scottish naval surgeon con-
ducted the first controlled experiment in the treat-
ment of scurvy in 1753, which proved that citrus
fruits protected seamen and cured scurvy. Not
until 40 years later were limes routinely issued to
British seamen to prevent scurvy. However, scurvy
continued into more recent times. It was prevalent

during the American Civil War, and in 1912 half
the men on Scott’s expedition to the South Pole
died of scurvy.
During initial stages of vitamin C deficiency, an
individual may feel listless. Wounds may heal
slowly and gums may bleed easily. Bruising occurs
easily. Minute hemorrhages appear around hair
follicles or stomach, buttocks, legs, and arms. Later
stages are characterized by weight loss, weakness,
painful muscles, swollen joints, spongy gums, and
loss of teeth. Vitamin C plays several important
roles that can be related to scurvy. Chief among
these is the requirement for vitamin C in
COLLAGEN.
The formation of mature collagen, the major struc-
tural protein of connective tissue, relies on the
availability of key building blocks called hydrox-
yproline and hydroxylysine. The production of
hydroxyproline from proline and of hydroxyl
lysine from lysine requires vitamin C. As a versatile
antioxidant and key support nutrient of the
immune system, vitamin C exhibits wide-ranging
benefits on health. Modest deficiencies do not
manifest themselves as scurvy, rather they increase
the susceptibility to infections and oxidative dam-
age leading to chronic diseases.
Infants relying on cow’s milk may be prone to
scurvy because much of the vitamin C is destroyed
during pasteurization. Infants require proportion-
ately higher levels of vitamin C because of their

high rate of tissue growth. Breast milk contains
adequate vitamin C to support infant develop-
ment.
Among adults, low-income elderly persons are
susceptible to scurvy if they do not eat fresh fruit
and vegetables. Overcooking destroys most vitamin
C in vegetables. Chronic disease, injuries, and
surgery are more likely in this group, and these
conditions deplete the body stores of this vitamin.
(See also
MALNUTRITION.)
Rajakumar, Kumaravel. “Infantile Scurvy: A Historical
Perspective,” Pediatrics 108, no. 4 (2001): e76.
seafood Edible marine fish and shellfish such as
CLAMS, mussels, scallops, OYSTERS, LOBSTERS, and
SHRIMP that represent an important, highly nutri-
tious food source. It is low in saturated fat and calo-
ries and is a good source of
PROTEIN, IRON, VITAMIN
B
12
, IODINE, PHOSPHORUS, ZINC, and COPPER. Fish and
fish oil are particularly rich in the omega-3 family
of polyunsaturated
FATTY ACIDS
, which help reduce
INFLAMMATION in conditions like ARTHRITIS and pso-
riasis, as well as reducing the risk of blood clot for-
mation, thus offering protection against
HEART

ATTACKS
. COD LIVER OIL
contains high levels of VITA-
MIN A and VITAMIN D, which may be toxic when
consumed in large amounts. Several servings per
week of the following fatty fish are recommended:
bluefish, butterfish, halibut, herring, mackerel,
striped bass, orange roughy, smelt, salmon, sar-
dines, trout, and pompano.
The larva of parasitic worms may contaminate
raw fish, including Pacific salmon, Pacific red snap-
per (rockfish), and herring; thus raw fish dishes
(sushi, sashimi,
CEVICHE, lomi-lomi) carry a risk of
parasitic disease, such as anisakiasis. Inadequately
smoked or salted fish can carry parasites. The
severe abdominal pain of such a disease is due to
acute intestinal inflammation. The parasite is killed
by cooking marine fish thoroughly. Pregnant and
nursing women, very young children, and elderly
people should avoid raw fish and shellfish to mini-
mize this risk.
Chemical Contamination
Chemical contaminants are another prominent
issue in seafood safety. Fish and shellfish are gen-
erally more susceptible to chemical contamination
than meat and poultry because they filter huge
amounts of water through their bodies and feed on
other organisms in which contaminants may be
concentrated. Clams and oysters can filter 15 to 20

gallons of water daily. While thorough cooking
destroys parasites and microorganisms, this does
not eliminate chemical pollutants like
LEAD, chlor-
dane,
DIOXIN, DDT, MERCURY, PBBs, and PCBs. Such
industrial chemicals were once widely used in
PES-
TICIDES, electrical insulation, plastics, dyes, and
other products. Over decades these environmental
pollutants have crept into the
FOOD CHAIN because
they are not readily broken down and because they
tend to accumulate in plants and animals.
seafood 573
Varying levels of pollutants have been reported
in both domestic and imported fish. While levels of
detected pollutants have generally fallen below
FDA tolerance limits, those limits were set when
fish consumption was lower and consequently
people accumulated less of these pollutants. The
level of pollutant can vary with the source, but in
many markets it is often difficult for the consumer
to determine the source of fish sold. Pollutant lev-
els in salmon from Pacific waters may be lower
than from other sources; however, the fish the con-
sumer buys may come from Chile, Norway, Eastern
Canada, Maine, as well as from Washington,
Alaska, or British Columbia.
Chemical pollutants may increase the risk of

certain cancers, birth defects, and neurological
damage in unborn children. However, the potential
health hazards of long-term, very low-level expo-
sure remain unknown. Because residue buildup
occurs over years, it may be hard to trace a disease
cause to a specific pollutant exposure.
Shellfish can accumulate disease-causing bacte-
ria and viruses when exposed to untreated sewage.
Harvesting is limited to waters that are certified as
being clean, although enforcing the policy is limited
by resources. Eating raw shellfish carries the risk of
gastrointestinal disease with symptoms such as diar-
rhea, cramps, nausea, and vomiting. Shellfish also
transmit hepatitis A virus. Well-cooked shellfish are
safer than raw or semi-cooked shellfish.
To ensure that seafood is as safe to eat as possi-
ble, consumers should
• Buy fresh seafood. Fish and shellfish spoil easily
and should be handled with care. Fresh fish
should have a mild “ocean” smell; they should
not smell “fishy” or smell like ammonia.
• Fresh seafood should be bought from reputable
merchants who can identify their source.
• Seafood should be refrigerated at home immedi-
ately after purchase to prevent bacterial growth,
minimize spoilage, and reduce the risk of
FOOD
POISONING
. Raw seafood that will not be eaten
within two days should be frozen. Most shrimp

have been frozen and thawed, and should be
cooked as soon as possible.
• Frozen seafood should be thawed in the refrig-
erator or in cold running water and not
refrozen. Other raw shellfish, including lobster,
should be alive when purchased.
• Cooked shellfish should be refrigerated and used
on the same day.
• Mussels, clams, and oysters should be moistened
and refrigerated to keep them alive rather than
stored in plastic bags. They should not be stored
for a long time in fresh water.
• Any shellfish that remains closed after steaming
should be discarded. Raw shellfish that remain
closed are dead and may have begun to decom-
pose.
• Consumers should follow the same rules in han-
dling raw seafood as when handling raw poultry
and raw meat to avoid contaminating cooked
dishes or fresh vegetables with bacteria: Wash
with soap and water all utensils, countertops,
cutting boards and hands that have come into
contact with raw seafood.
• Consumers should eat a variety of seafoods
rather than a single source to minimize overex-
posure to pollutants. Elderly people, young
children, pregnant women, patients with com-
promised immune systems or with liver disease
should avoid eating raw seafood.
Connor, W. E. “Importance of n-3 Fatty Acids in Health

and Disease,” American Journal of Clinical Nutrition 71
(2000): 171S–175S.
seafood inspection Fish and shellfish are among
the most perishable foods, yet seafood is one of the
least regulated foods; it remains the only flesh that
does not undergo mandatory inspection. In con-
trast, meat and poultry processing facilities are
inspected daily. A single-time
FDA inspection of
most U.S. seafood processing plants revealed a rel-
atively low violation rate of up to 5.1 percent of
plants, depending on the region.
An estimated 20 percent of food-borne illness is
caused by seafood. Seafood can be contaminated
by bacteria, viruses, parasites, and industrial wastes
and pollutants. While the National Academy of Sci-
ences has concluded that most seafood is safe to
eat, this advisory organization has also recom-
mended increased inspection and regulation of the
industry. Fish testing in specific areas is left to state
agencies, and testing for chemical contaminants
574 seafood inspection
remains scattered. Only very small numbers or
samples of fish are monitored for chemical conta-
minants. The FDA established a new Office of
Seafood in 1991 to address this issue. In 1994, the
FDA launched a seafood safety initiative designed
to keep contaminated seafood off the market
shelves. Seafood processors need to maintain
detailed records of safety procedures; to identify

where shellfish were harvested; to catch fish only
from waters the government has certified as being
clean; and to store their catch at proper tempera-
tures. Ready to eat seafood will have to be cooked
and stored at safe temperatures as well.
sea salt A less pure form of table salt (SODIUM
chloride). Sea salt contains low levels of certain
minerals found in sea water. Using 3.5 g of sea salt
would supply 22 percent of the
REFERENCE DAILY
INTAKE
(RDI) of MAGNESIUM; 2.2. percent of the RDI
of
IODINE; 2.7 percent of the RDI of CALCIUM. Mag-
nesium carbonate is the additive used to prevent
caking. This is more healthful than aluminum sili-
cate used for the same purpose in refined salt. Sea
salt is not iodized and lacks iodine. As a source of
sodium, sea salt carries with it the same risks for
high blood pressure (
HYPERTENSION) as ordinary
table salt in susceptible people. (See also
TRACE
MINERALS
.)
seaweed A large family of marine ALGAE
. Edible
seaweed is one of the richest sources of vitamins
and minerals. Sea vegetables provide
IODINE, SELE-

NIUM, IRON, CALCIUM, PHOSPHORUS, and MAGNESIUM,
as well as
BETA-CAROTENE, VITAMIN E, and the B
COMPLEX
. Sea vegetables are not an adequate
source of vitamin B
12
because they possess sub-
stances that are inactive analogs or forms of the
compound that the body cannot use. Vegetarians
who do not eat milk, eggs, fish, or meat should
consider taking a vitamin B
12
supplement rather
than relying on seaweed.
Traditionally, Asian diets include a variety of
seaweed. The edible algae can be categorized as
brown algae and red algae. Brown algae are repre-
sented by arame, hijiki, kelp, kombu, and wakame.
Arame is a Japanese product; it is softened by pro-
longed cooking, sun-dried, and finally sliced into
strands and packaged. Arame contains B complex
vitamins and minerals. The calcium content is
1,170 mg per 100 g. Hijiki is found in the Far East;
100 g (dry weight) contains calcium, 1,400 mg;
iron, 29 mg; plus
BETA-CAROTENE and B complex
vitamins. This seaweed is dried, steamed to stiffen
it, again dried, then soaked in arame juice and
dried for market. Kelp refers to a large family, and

members are used commercially as a source of food
additives,
EMULSIFIERS, thickeners, and STABILIZERS
.
Kelp is dried and sold whole, or powdered when it
is used as a flavoring. Kelp can be steamed, pickled,
or boiled. It contains significant calcium and other
minerals; 100 g contains calcium, 1,093 mg;
sodium, 3,007 mg; and potassium, 5,273 mg.
Kombu is a general name for several species of
brown algae. Dashi consists of broad strips and is
used in soups, while tororo is shaved into slivers
that can be marinated. Kombu is often used with
root vegetables, rice, and vegetables. It provides sig-
nificant beta-carotene, 430 retinol equivalents per
100 mg, as well as the B complex and vitamin C.
Wakame comes from Japan. It is dried and
processed for preservation. It can be added to soups,
like miso soup, cooked as a vegetable, used as a gar-
nish, or soaked and then added to salads. Wakame
contains calcium, iron, and vitamins; 100 g provides
calcium, 1,300 mg; iron, 13 mg; niacin, 10 mg; and
vitamin C, 15 mg. Brown sea vegetables like kombu
contain alginic acid and other ingredients that bind
toxic heavy metals like strontium, cadmium, and
radium. Alginic acid is used to treat cadmium poi-
soning and help remove it from the body.
Red algae include carragheen and nori. Car-
ragheen yields a gum called
CARRAGEENAN that is

used in prepared foods, primarily for its ability to
form gels in puddings, jellies, and the like. Car-
rageenan inhibits herpes simplex virus (oral and
genital forms) as well as tumor-inducing
RNA
viruses in test tube experiments. It also provides
(per 100 g): calcium, 885 mg; sodium, 2,892 mg;
and potassium, 2,844 mg. Nori is a cultivated red
sea vegetable. Fresh nori is washed, chopped into
fragments, dried, and packaged. Sheets of nori are
wrapped around rice used in sushi and California
rolls. Nori provides (per 100 g): calcium, 260 mg;
iron, 12 mg; high levels of beta-carotene, 11,000
retinol equivalents; thiamin, 25 mg; niacin, 10 mg;
and vitamin C, 20 mg.
seaweed 575
Seaweed has an ancient history of use in Eastern
medicine, including Chinese and Indian medicine
(Ayurvedic medicine). It has been used to treat
intestinal parasites.
GOITER, enlarged thyroid due to
iodine deficiency, is effectively treated by seaweed
because of its high iodine content. Certain species
of seaweed have been used in folk medicine to
treat high blood pressure, constipation, wounds
and ulcers,
GOUT, liver and kidney ailments, men-
strual irregularities, and to improve digestion.
Alginic acid is used in some antacids to treat
ACID

INDIGESTION
and to treat wounds. Fucoidin is
another type of complex carbohydrate (polysac-
charide) from seaweed. In animals, this material
inhibits chemically-induced cancers. (See also
FOOD
ADDITIVES
; MACROBIOTIC DIET.)
Wein, Bibi. “The World’s Healthiest Diet,” Lifestyles 17,
no. 3 (March 1995): 172–175.
secretin A HORMONE released by the small intes-
tine that blocks the release of gastric juice and
STOMACH ACID. Secretin slows the movement (PERI-
STALSIS) of material down the gastrointestinal tract.
It stimulates the secretion of
BICARBONATE by pan-
creatic duct cells to neutralize the acidic, partially
digested food discharged by the
STOMACH
into the
small intestine. To further prepare the intestine for
DIGESTION
, secretin stimulates bile production to aid
fat digestion and the secretion of intestinal juice
and digestive enzymes. Secretin release is triggered
by food entering the small intestine, including par-
tially digested carbohydrate and fat, as well as by
fluids that contain high or very low concentrations
of ions. (See also
ENDOCRINE SYSTEM.)

selenium A
TRACE MINERAL nutrient with anti-
cancer and antiaging properties. Selenium helps
protect cells against oxidative stress. As a part of
the enzyme
GLUTATHIONE PEROXIDASE, selenium
serves as an
ANTIOXIDANT by destroying highly reac-
tive chemicals that can form
FREE RADICALS. Glu-
tathione peroxidase destroys
HYDROGEN PEROXIDE,a
naturally occurring chemical that is a powerful oxi-
dizing agent. Hydrogen peroxide is produced for
antimicrobial defense by macrophages, a type of
white blood cell that engulfs foreign invaders, and
it is a by-product of another antioxidant system
(
SUPEROXIDE DISMUTASE) that destroys a highly reac-
tive form of oxygen called superoxide. Glutathione
peroxidase neutralizes oxidative damage to lipids in
cell membranes, thus limiting their damage due to
free radical attack. Selenium may possess other
antioxidant properties as well.
Selenium is generally recognized as an anti-
cancer agent. In selenium-deficient experimental
animals,
LIVER cells become defective and more
prone to become cancerous when activated. Stud-
ies show that populations with a low selenium

intake are more prone to gastrointestinal, breast
and rectal cancer. Deficiency of selenium leads to
lowered glutathione peroxidase activity. Further-
more, extensive Chinese studies have suggested
that selenium supplementation provides protec-
tion against hepatitis B and liver cancer. Selenium
may inhibit the development of cancer by blocking
the activation of certain cancer-promoting genes,
by inhibiting viruses linked to cancer or by sup-
porting healthy cell division and protecting cells
against oxidative damage that could damage their
DNA.
Selenium supports a healthy
IMMUNE SYSTEM,
where it stimulates antibody production and defen-
sive cells (lymphocytes, macrophages and natural
killer cells). Some AIDS patients may be selenium
deficient. Selenium can block mercury, arsenic,
and cadmium poisoning. Damaged heart muscle
(cardiomyopathy) has occurred in patients fed
intravenously mixtures that lacked selenium, and
populations in areas of China characterized by
regional selenium deficiency are more disease
prone.
OSTEOARTHRITIS in Chinese children has also
been linked to selenium deficiency.
RECOMMENDED DIETARY ALLOWANCES (RDA) pub-
lished in 1989 proposed a selenium RDA for the
first time as 70 mcg/day for men and 55 mcg for
nonpregnant, nonlactating women. Obtaining ade-

quate selenium is a growing problem in the United
States. Regions like the Pacific Northwest, the
Great Lakes region, and some southern states
(Georgia and the Carolinas) possess low soil con-
centrations of selenium, and vegetables and grains
growing in depleted soils contain only low levels of
selenium. Possibly, acid rain prevents plants from
taking up this mineral from soil. The average U.S.
intake is about 100 mg/day.
Good dietary sources of selenium include organ
meats, such as liver and kidney;
BREWER’S YEAST;
576 secretin
ocean FISH and SHELLFISH; and red MEAT. Vegetable
sources (if grown in soil with enough selenium) are
ONIONS, GARLIC, MUSHROOMS, and BROCCOLI. Aspa-
ragus, cabbage, and whole grains contain small
amounts of selenium.
FRUITS and most VEGETABLES
and drinking water generally provide little sele-
nium. Supplements containing inorganic selenium
(sodium selenite or sodium selenate) should prob-
ably be taken separately from large amounts of vit-
amin C to avoid interference.
Chemically combined selenium represents the
most prevalent form of the selenium in the typical
diet. Selenium can replace sulfur in the amino
acids
CYSTEINE and METHIONINE to form the analogs,
selenocysteine and selenomethionine. Selenocys-

teine occurs in a variety of proteins including glu-
tathione peroxidase and is found in meat.
Selenomethionine cannot be synthesized by the
body and is supplied in the diet by a variety of
foods. It can substitute for methionine in a variety
of the body’s proteins. The breakdown of methion-
ine and selenomethionine releases cysteine and
selenocysteine, respectively.
Safety
Toxicity can occur with daily consumption of 5 mg.
Toxic levels of selenium occur in agricultural drain-
water in some states. Certain regions are character-
ized by high levels of selenium (North and South
Dakota and the San Joaquin Valley of California).
Soils with high selenium cause unusually high lev-
els in plants such as wheat. Symptoms of selenium
toxicity include skin sores, garlic breath, fingernails
with ridges and bumps, hair loss, and lethargy.
Severe toxicity is indicated by fragile, black nails,
metallic taste, dizziness, peripheral nerve damage,
nausea, weight loss, and jaundice. Children, elderly
persons and people with chronic illnesses may tol-
erate less selenium in their diets, while physically
active people may tolerate more. Sodium selenite,
the inorganic form of selenium, can cause cancer at
very high doses. Organic selenium that occurs in
foods is not carcinogenic.
Cammack, P. M. “Selenium Deficiency Alters Thyroid
Hormone Metabolism in Guinea Pigs,” Journal of
Nutrition 125 (1995): 302–308.

self-rising flour See BAKING SODA.
semolina Milled durum WHEAT used to produce
PASTA like macaroni and spaghetti. The high protein
(gluten) content of durum wheat lends itself to
elastic, resilient dough that is suitable for the
mechanical processing involved in making pasta.
senility An old-fashioned term for memory loss
associated with
AGING. This phenomenon usually
begins with loss of short-term memory and the
ability to process new information quickly. Recol-
lection of past events also slows down.
ALZHEIMER
’S
DISEASE
is the most common of the more than 70
types of dementia. It currently affects 4 million
Americans but experts believe that will rise to 22
million by 2025.
Many of the people who appear to be suffering
from dementia and forgetfulness may instead have
nutritional deficiencies, including
VITAMIN B
12
defi-
ciency due to inadequate absorption. The uptake of
this vitamin declines with age, especially in those
with stomach troubles. Injections of vitamin B
12
,

or taking large doses in tablet form, is a preventive
measure.
Forgetfulness, learning difficulties, and prob-
lems remembering new things can frequently be
caused by overmedication. Many elderly U.S citi-
zens (65 or older) take prescription drugs they
should not be using, some of which may cause con-
fusion or amnesia. Similar problems may be due to
adverse reactions to medication. As an example,
DIURETICS
(water pills) can cause excessive sodium
loss, especially for those on a salt-restricted diet.
This condition, called hyponatremia, is easily
detected if the change is dramatic. However, if the
change is slow, it is more difficult to detect and the
symptoms match senile dementia. This condition is
reversible if caught soon enough. Memory loss is
also worsened by drugs blocking the formation of
neurotransmitters. Drugs that fall into this category
include sleeping pills and medications for reducing
tremors, decreasing stomach acid and calming
nerves. Other possible causes of forgetfulness
include high fever, minor head injuries,
DEPRES-
SION, loneliness, and boredom. To combat senility,
exercise the brain by keeping mentally active and
avoiding drugs that characteristically cause a dry
mouth because this class of drugs may interfere
with neurotransmitters.
senility 577

Prescription drugs Hydergine, the hormone
vasopressin (antidiuretic hormone), and unipoce-
tine have been used to enhance memory. Lipids
like phosphatidylserine and phosphatidylethano-
lamine play structural roles in cell membranes, and
treatment with these substances suggests some
improvement in certain patients with Alzheimer’s
disease.
CHOLINE and LECITHIN (the phospholipid
derivative of choline) may improve short-term
memory in susceptible patients. However, they do
not appear to alter the course of Alzheimer’s dis-
ease. Treatment with phosphatidylcholine and pre-
scription drugs like physostigmine and Hydergine
have yielded mixed results. Three decades of
research suggest that phosphatidyl serine benefits
cognitive function, including memory and learning
in elderly people. Other studies indicate that a
derivative of the amino acid
CARNITINE, L-acetylcar-
nitine, shows promise in moderating age-related
depression, as well as the effects of stroke and
nerve degeneration related to
DIABETES MELLITUS.
(See also
FOOD; GINKGO; PREBIOTICS.)
Le Bars, P. L. “A Placebo-Controlled Double-Blind, Ran-
domized Trial with a Special Extract of Ginkgo Biloba
in Dementia,” JAMA 278 (1997): 1,327–1,332.
sensitivity See FOOD SENSITIVITY

.
sequestrants (chelating agents) Agents used to
reduce color changes and
SPOILAGE in canned
foods,
PROCESSED FOODS, and bottled salad dress-
ings. Sequestrants bind metal ions like iron, which
catalyze the reaction of oxygen with sensitive
materials in food. Examples of sequestering agents
are
CITRIC ACID, malic acid, tartaric acid, and EDTA.
Citric acid is used in ice cream, sherbet, fruit drinks,
soft drinks, jellies, canned fruits and vegetables,
and cheese. It is considered a safe additive. EDTA is
widely used in salad dressings,
MARGARINE, MAYON-
NAISE and sandwich spreads, prepared fresh fruit,
potatoes, canned shellfish, beer, and soft drinks.
EDTA too is considered safe. (See also
FOOD ADDI-
TIVES; MINERALS.)
serine (Ser, L-serine) A nonessential AMINO ACID
required to synthesize proteins. Serine plays a role
in many synthetic reactions that require
FOLIC ACID,
VITAMIN B
6
, and NIACIN. It can be converted to the
simplest amino acid,
GLYCINE, and vice versa. Serine

can assist in the synthesis of
PURINES and PYRIM-
IDINES
, the building blocks of DNA and RNA. Serine
can be converted to ethanolamine and
CHOLINE,
two nitrogen-containing compounds required for
phospholipid synthesis and cell membrane forma-
tion, and to certain
NEUROTRANSMITTERS, brain
chemicals required to transmit signals in nerves.
Serine is classified as a “glycogenic” amino acid be-
cause during
STARVATION
it can be converted to
BLOOD SUGAR
to fuel the brain. (See also AMINO ACID
METABOLISM
.)
serotonin A chemical found in the brain and
defensive cells of connective tissue. Mast cells, a
type of defensive cell lodged in connective tissue,
produce serotonin from the essential amino acid
TRYPTOPHAN to slow blood flow in damaged areas
because it acts as a powerful vasoconstrictor. In the
brain, serotonin functions as a neurotransmitter, a
chemical required for the transmission of nerve
impulses. Serotonin is involved in inducing sleep,
sensory perception, and temperature. It diminishes
pain, reduces

APPETITE, and has a calming effect.
Certain antidepressants such as Prozac boost sero-
tonin levels. Diet can possibly affect mood by alter-
ing brain serotonin levels. Eating carbohydrates
may reduce the level of most amino acids in the
blood except tryptophan, so that this amino acid
can more easily penetrate the
BLOOD-BRAIN BARRIER
without competing with other amino acids.
According to this hypothesis, as the level of trypto-
phan rises in the brain, more serotonin is synthe-
sized, leading to relaxation and decreased alertness.
(See also
NERVOUS SYSTEM.)
serum The clear, straw-colored fluid remaining
after blood has clotted. Serum contains
CHOLES-
TEROL (serum cholesterol) in the form of LOW-DEN-
SITY LIPOPROTEIN (LDL, the less desirable form) and
HIGH-DENSITY LIPOPROTEIN (HDL, the more desirable
form); fat (
TRIGLYCERIDES); proteins produced by
the liver such as serum
ALBUMIN; ELECTROLYTES
(ionic minerals like SODIUM, POTASSIUM and CHLO-
RIDE); waste materials like UREA and URIC ACID; and
nutrients such as
AMINO ACIDS and BLOOD SUGAR
(GLUCOSE). Serum is often used in the clinical labo-
578 sensitivity

ratory to measure these parameters for diagnosis,
rather than whole blood, which contains cells that
can alter these parameters. For example, red blood
cells possess their own complement of enzymes,
lipids, and minerals.
serum lipids See
CHOLESTEROL.
sesame (Sesamum indicum) An annual tropical
plant grown since ancient times for its edible seed
oil. Sesame was cultivated in Palestine and Syria as
early as 3000
B.C. It is now cultivated in China,
India, Burma, and Mexico; the United States is a
major importer. Sesame seeds contain 50 percent
oil by weight; the oil can be extracted from
crushed, whole seeds. The seed is dehulled for
human consumption because its hull contains 2
percent to 3 percent
OXALIC ACID, which binds min-
erals and gives it a bitter flavor. The U.S. imports 70
million pounds of sesame seeds annually; most of
this is used for hamburger buns. Ground sesame
seeds are used in hummus and tahini (a sesame
seed paste). Halvah is a confection made with
ground sesame seeds. Sesame seeds are used with
stir-fried vegetables and fried poultry in Asian cui-
sine.
Sesame oil is more saturated than
VEGETABLE
OILS

like safflower, corn, or soybean oil, which all
contain more than 50 percent polyunsaturated
fatty acids. Sesame oil contains 43.8 percent
polyunsaturated fatty acid (
LINOLEIC ACID); 14.6
percent saturated fatty acids (mainly
PALMITIC ACID
and
STEARIC ACID); and 41.5 percent monounsatu-
rated fatty acids (
OLEIC ACID). The oil has a strong
nutty flavor and is often used in stir-fry meals. The
nutrient content of sesame seeds (15 g) is: 84 calo-
ries, protein, 3.6 g; carbohydrate, 0.6 g; fat, 7.1 g;
calcium, 18 mg; iron, 1.1 mg; thiamin, 0.29 mg;
riboflavin, 0.03 mg; niacin, 0.8 mg. (See also
HYDROGENATED VEGETABLE OIL.)
set point See DIETING; WEIGHT MANAGEMENT.
shellfish Mollusks and crustaceans that have
been long used as food sources. Univalve mollusks
such as abalone are enclosed in a single shell;
bivalve mollusks with a two-part shell include
CLAMS mussels, OYSTERS, and scallops. Cephalopods
(creatures with tentacles, like squid) are a type of
mollusk. Crustaceans, which possess a tough outer
layer and segmented bodies and legs, include
CRAB,
LOBSTERS, crayfish, prawns, and SHRIMP. Shellfish
provide rich sources of protein low in saturated fat
and total fat, and

TRACE MINERALS such as IODINE,
ZINC, and COPPER. Generally, shellfish contain the
usual amounts of cholesterol as found in meat.
Shrimp contain somewhat higher levels, though
less than found in eggs. Like ocean fish, shellfish
contain omega-3 oils that offer protection against
heart disease.
Raw shellfish are a major source of severe, food-
borne disease. Disease organisms carried by shell-
fish include salmonella and hepatitis A virus.
Bacteria can cause gastroenteritis (inflamed stom-
ach and intestines) with diarrhea, nausea, vomit-
ing, and cramps. Shellfish are bottom feeders and
filter vast amounts of water, therefore they tend to
accumulate waste products and disease-producing
bacteria and viruses when grown in waters conta-
minated by sewage. Clams and oysters can filter 15
to 20 gallons of sea water daily.
FDA and state inspections are designed to make
certain that shellfish are harvested from clean
waters. However, regulation of the shellfish indus-
try is spotty because few agents are available to
monitor 10 million acres of approved shellfish beds
in U.S. coastal waters. To meet the increased con-
sumer demand, the fishing industry is taking fish
and shellfish closer to shore, where pollution is
higher and the risk of polluted
SEAFOOD is higher.
Raw or undercooked shellfish are the major
seafood hazards. The bacterium Vibrio vulnificus

produces a toxin causing a shellfish poisoning asso-
ciated with contaminated seafood, especially oys-
ters from the Gulf Coast. Immune compromised
people and those with liver disease (cirrhosis) are
most vulnerable. The toxin can cause skin ulcers
and occurs as normal marine flora in warmer tem-
perate waters. Its production is not associated with
pollution.
RED TIDE is an explosive growth of a microscopic
marine algae. Poisonous dinoflagellates produce
neurotoxins that are not destroyed by cooking.
Paralytic shellfish poisoning is caused by Gonyaulax
catenella and G. acetenella along Pacific coasts and G.
tamarensis in the Bay of Fundy and in the St.
shellfish 579
Lawrence estuary on the North Atlantic. Symp-
toms begin with numbness in lips and tongue,
spreading to arms and legs and respiratory distress.
Red tide can cause blood poisoning and death in
high-risk individuals—patients with liver disease,
AIDS, or alcoholics. Mussels gradually destroy or
eliminate bound poisons after an algal bloom. In
general, raw oysters should be avoided during the
warmer months, April to October.
Razor clams from U.S. Pacific Northwest beaches
can be contaminated with domoic acid, a naturally
occurring neurotoxin that causes nausea, fever,
abdominal cramps, short-term memory loss, coma,
and death in severe cases. This toxin is produced by
marine plankton. Internal organs of Dungeness

crab harvested off the coasts of California, Oregon,
and Washington may be contaminated, although
the crab meat itself is safe. (See also
SEAFOOD
INSPECTION
.)
sherbet A frozen DESSERT prepared from fruit
juice or fruit puree, sugar, milk, egg white, or
gelatin or dipped marshmallows. In contrast, sor-
bets are fruit-based frozen desserts that do not con-
tain dairy products. (See also
ICE CREAM
.)
shigellosis A severe type of FOOD POISONING
caused
by shigella, an intestinal bacterium. Symptoms
include very severe
DIARRHEA, lasting several days,
with possible bloody stools and accompanied by
fever and possibly
DEHYDRATION. Most people
recover fairly rapidly, even without treatment with
antibiotics. However, shigellosis can be life-threaten-
ing to children and to the elderly. Shigella is carried
by fecal matter, and the disease can be transmitted
by food handlers with poor hygiene. State law
requires that cases of shigellosis be reported to
health departments. (See also
SALMONELLA.)
shiitake mushroom (Lentinus edodes; forest mush-

room) An edible
MUSHROOM especially popular in
Asia. Shiitake mushrooms are cultivated commer-
cially and are available in United States markets.
Shiitake contains a broad spectrum of amino acids,
potassium, and ergosterol, a substance that can be
converted to vitamin D in the presence of sunlight.
In addition, shiitake mushrooms have been used in
Asian medicine for thousands of years. Shiitake
contains carbohydrate materials and polysaccha-
rides, including lentinan, which stimulates the
immune system and which has antitumor activity.
Lentinan may boost white blood cells called T
helper cells that gear up the immune system. Shi-
itake extracts also boost antiviral defenses by
increasing interferon production. Extracts can
lower blood cholesterol levels.
shock See
ANAPHYLAXIS.
short-chain fatty acids Very small fatty acids that
have an odor (volatile fatty acids). Short-chain
fatty acids are produced by the anaerobic fermen-
tation of carbohydrate by colonic bacteria. With
normal digestion, typically the main source of fer-
mentable carbohydrate is dietary
FIBER, plant cell
wall materials, and undigested starch. Short-chain
fatty acids include
ACETIC ACID (acetate, a two-car-
bon acid);

PROPIONIC ACID (propionate, a three-car-
bon acid); and
BUTYRIC ACID (butyrate, a
four-carbon acid).
Short-chain fatty acids are readily absorbed by
the colon and can be considered a major factor in
human energy metabolism. It is estimated that
short-chain fatty acids produced by colonic bacteria
can satisfy 5 percent to 10 percent of the body’s
energy needs. Acetic acid and propionic acid are
used by the liver, while butyric acid is a preferred
fuel by cells lining the gut. Indeed, butyrate is a pri-
mary energy source for these cells. In addition,
butyrate helps guide the development and mainte-
nance of colonic cells and may decrease suscepti-
bility to colon
CANCER and colitis.
More than usual amounts of fermentable carbo-
hydrate enter the colon with high-fiber diets and
during carbohydrate
MALABSORPTION and maldiges-
tion, leading to increased production of short-chain
fatty acids. The production of short-chain fatty acids
lowers intestinal ammonia levels liberated through
bacterial metabolism and limits the uptake of this
waste product. Ammonia can induce abnormalities
in intestinal cells. Short-chain fatty acids also inhibit
the growth of certain pathogenic species like salmo-
nella, and the resulting lowered colonic pH
(increased acidity) favors

VITAMIN K absorption,
MUCUS secretion, and magnesium uptake. (See also
FAT METABOLISM; INTESTINAL FLORA.)
580 sherbet
shortening A FAT added to a food item to keep it
soft during baking. By dispersing fat droplets
throughout a dough, starch and grain protein do
not congeal into a compact mass when cooked.
BUTTER (milk fat), LARD (pork fat), and TALLOW
(beef fat) are traditional shortening agents. Veg-
etable shortenings contain hydrogenated vegetable
oils. These are solids, unlike the original oils. They
are prepared from hydrogenated oils with varying
melting points, and with varying degrees of soft-
ness. Vegetable shortening is often prepared from
CORN OIL
, COTTONSEED OIL,
OLIVE OIL, PEANUT oil,
PALM OIL, SAFFLOWER oil, SESAME oil, or SOYBEAN oil.
Regardless of form, all fats and oils provide nine
calories per gram, more than twice as much as
derived from carbohydrate and protein (four calo-
ries per gram).
Shortening is used for biscuits, bread, cookies,
and pie crusts. The amount of shortening varies
with the recipe. Bread and rolls contain 1 percent
to 2 percent shortening; cakes, 10 percent to 20
percent, and pastries, 30 percent. When shorten-
ings are used for baking mixes, whipped topping,
icing, and filling, various emulsifying agents are

included. These include
MONOGLYCERIDES (glycerol
with only one fatty acid). Emulsifiers allow water
to be mixed with the shortening without separa-
tion. (See also
DIETARY GUIDELINES FOR AMERICANS;
FAT METABOLISM
; VEGETABLE OIL
.)
shrimp A type of SHELLFISH with 10 legs that
range in size from 0.5 in. to several inches. When
cooked, shrimp turn red due to a chemical change
in the shell pigment. Typically, the parts of cooked
shrimp sold at markets are the abdominal region
and tail parts, after the heads have been removed.
Shrimp is a high-protein food that is also a good
source of
CALCIUM. Shrimp contains somewhat
higher than usual levels of cholesterol, though less
than found in eggs. Shrimp can be canned, con-
verted to shrimp paste, breaded and fried, or stir-
fried. The nutrient content of 3.5 oz. (100 g) is: 109
calories; protein, 23.8 g; fat, 1.5 g; cholesterol, 152
mg; calcium, 320 mg; iron, 2.2 mg; thiamin, 0.03
mg; riboflavin, 0.03 mg; niacin, 3.7 mg.
silicon The second most common element on the
surface of the Earth and widely found in plants and
water. Silicon is also found in the skin,
BONE, and
connective tissue of animals. It is an essential nutri-

ent in animals, required for normal skeletal devel-
opment of rats and chicks, for example. It seems
probable that silicon is essential for humans,
although this remains to be established. No
RECOM-
MENDED DIETARY ALLOWANCE
has been established
for silicon. Silicon participates in the formation of
connective tissue where it forms complexes
between protein and acidic polysaccharide com-
plexes. Acidic polysaccharides (
GLYCOSAMINOGLY-
CANS
) contribute to the gelatinous material that
holds cells together. In humans, the silicon content
of the aorta, the skin, and the thymus decreases
with age.
Silicon is widely distributed in whole grains,
organ meats like liver, and red meat. Most of the
silicon of whole grains is lost when white flour
is prepared, and highly processed foods contain lit-
tle silicon. The typical diet supplies approximately
1 g per day. Within the confines of the typical
diet, silicon is nontoxic. (See also
SKELETON; TRACE
MINERAL
.)
simple carbohydrate See CARBOHYDRATE.
single-cell protein Food PROTEIN derived from
cultured bacteria,

YEAST, fungi, and algae. Algae
(seaweed) has long been used as food. Brewer’s
yeast, a by-product of the brewing industry, and
TORULA YEAST are widely available food supple-
ments. The potential of cultured microorganisms
serving as an edible protein source is huge. A
single-cell fermenter covering 0.8 sq km (one-third
of a square mile) could theoretically supply 10 per-
cent of the protein requirement of the world’s
population. By-products of the food, paper, and
chemical industry can be fermented by many mic-
roorganisms as inexpensive energy sources. These
include methane,
ALCOHOL, STARCH, MOLASSES,cel-
lulose, and animal waste products. Even fewer
requirements are needed for algae; photosynthetic
organisms can be grown in illuminated ponds sup-
plied with mineral nutrients.
Problems associated with single-cell protein
have limited its development as a major food
source. Most single-cell protein is not palatable
unless processed to eliminate bitter or unpleasant
single-cell protein 581
tasting materials. Digestibility of single-cell protein
varies with the sources. Cooking algae increases its
digestibility, but the digestibility of yeast is little
altered by processing. The high nucleic acid content
of single-cell organisms leads to increased purine
uptake. When purines are metabolized, uric acid
output rises and increases the risk of

GOUT in sus-
ceptible people. Furthermore, toxic materials and
pollutants can contaminate single-cell protein.
Another consideration is the fact that single-cell
protein is generally deficient in the dietary essential
AMINO ACIDS
, LYSINE, and
METHIONINE. Though the
amino acid profile is more balanced than in cereal
grain protein it remains inferior to animal protein.
Genetically engineered microorganisms may over-
come this deficiency. (See also
FOOD CHAIN; HUNGER;
MEAT; PHOTOSYNTHESIS.)
skeleton The collection of bones that provides
the framework and protective covering for many
organs of the body including the brain, heart, and
spinal cord. Unlike the
NERVOUS SYSTEM, the
IMMUNE SYSTEM or the ENDOCRINE SYSTEM, the skele-
tal system plays a passive role in maintaining nor-
mal body function (
HOMEOSTASIS). The skeletal
system protects internal organs; vertebrae protect
the spinal column; the cranium, the brain; the rib
cage, the heart, and the lungs; the pelvic bones, the
reproductive organs. Bones store calcium and
phosphorus, which can be released and distributed
to other parts of the body via the bloodstream. Red
bone marrow in certain bones yields blood cells;

RED BLOOD CELLS, some white cells and blood
PLATELETS required for blood clotting. Fat in bone
marrow represents stored
ENERGY. The human
skeleton contains 206 bones and is held together by
tough connective tissue and cartilage. Skeletal
muscles adhere to bones via tendons to promote
movement.
Bones range in size from the robust femur to the
delicate, intricate bones of the wrist and ankle.
Physical growth during maturation from infancy to
adulthood entails a dramatic increase in bone mass
and size. Nearly 67 percent of bone represents a
mineral matrix, the compound calcium phosphate,
composed of the nutrients
CALCIUM and PHOSPHO-
RUS. Many other nutrients are required in the
growth and maintenance of the skeletal system.
MAGNESIUM and FLUORIDE are also complexed with
calcium phosphate to help harden the bone matrix.
BORON may reduce calcium and magnesium
losses from bone in post-menopausal women. The
skeleton requires a healthy connective tissue.
MAN-
GANESE
is required for the formation of muco-
polysaccharides, while
COPPER and VITAMIN C are
required for the formation of
COLLAGEN and

ELASTIN
, proteins of connective tissue and tendon,
respectively. Bone-forming cells are maintained by
VITAMIN A
among other nutrients. VITAMIN D
,
together with ample calcium, phosphorus, and
magnesium, promotes normal skeletal develop-
ment and prevents
RICKETS in children. In adults,
vitamin D prevents bone thinning and softening.
(See also
OSTEOMALACIA; OSTEOPOROSIS.)
skim milk See MILK.
skin The outer surface of the body and its largest
organ. The skin of an adult covers a surface area of
2 square meters and forms the primary physical
barrier to the external environment, bacteria, and
other microorganisms. The skin also helps regulate
body temperature through heat lost by the evapo-
ration of sweat and by changes in blood flow to the
skin. A limited amount of body wastes and chemi-
cal toxic load can also be eliminated through sweat.
The skin supports the sense of touch via sensory
nerve endings embedded there. These nerves react
to temperature, pressure, pain, and touch. The skin
is responsible for synthesizing vitamin D
3
from a
stored precursor when exposed to ultraviolet light.

Finally, certain types of cells embedded in underly-
ing layers are important components of immunity,
the ability to ward off disease.
Nutrient Support
The chief constituent of the skin is
COLLAGEN,a
structural protein requiring vitamin C. Collagen
and
ELASTIN are fibers of connective tissue that
keep the skin smooth and toned.
VITAMIN C and
COPPER are trace nutrients that support the synthe-
sis of elastin proteins. Vitamin C and
VITAMIN E
together with SELENIUM are required for a healthy
skin. They are powerful scavengers of
FREE RADI-
CALS, the highly reactive chemicals formed by sun-
light and oxygen, smog, pollutants, and other
582 skeleton
factors. Essential fatty acids, LINOLEIC ACID and
ALPHA LINOLENIC ACID, which occur in seed oils, are
important in maintaining a lustrous skin. Seba-
ceous glands secrete an oily material called sebum,
which is a mixture of oils, cholesterol, protein, and
inorganic salts. This oily film protects hair and skin
from drying out; prevents excessive evaporation
from the skin; keeps the skin soft and pliable; and
blocks the growth of certain bacteria. It forms a
water-impermeable barrier and prevents the skin

from becoming saturated with water.
AGING brings marked changes in the skin. The
skin appears rougher, drier, and thinner, and the
cushioning layer of fat beneath the skin dimin-
ishes. There are fewer melanocytes, cells that pro-
duce pigment to protect against sunlight’s
ultraviolet damage, and there is less collagen and
elastin and that which remains may be damaged.
All structures in the skin can be affected by
chronic exposure to U.V. light. U.V. light reacts with
cells by initiating free radical reactions. Free radi-
cals attack cells and damage their DNA, which
accounts for most skin damage. Sunburn is an
injury to the skin due to ultraviolet rays that may
lead to cell death and mutations. The skin becomes
leathery, with wrinkles, lines, sagging skin areas,
wart-like or scaly precancerous growths, yellow
discoloration, and abnormal elastic tissue.
The first line of
IMMUNE SYSTEM defense in the
skin are Langerhans cells. These sentries can detect
the intrusion of foreign materials and quickly sig-
nal other components of the immune system to
counterattack. U.V. light whether from tanning
parlors or from sunlight suppresses these cells.
Photosensitivity can aggravate the reaction to
the sun’s rays. Certain foods (citrus fruits, for
example), deodorant soaps, Retin-A, antibiotics,
tranquilizers, and
DIURETICS (water pills) contain

materials that can accentuate a reaction to sunlight
such as burning and development of age spots. By
minimizing ultraviolet exposure, new connective
tissue can replace the old with adequate nutrition.
Vitamin E, vitamin C, and B complex vitamins
promote repair and cellular growth. These antioxi-
dants also function as an anti-inflammatory agents
that aid in the repair of cell damage. Flaxseed oil,
borage oil, and
EVENING PRIMROSE OIL provide
essential fatty acids also needed for skin mainte-
nance.
COLLAGEN has a moisturizing effect when
applied in skin lotion, but it is not absorbed or used
by the skin when applied topically. Whether the
skin can be nourished by external vitamin applica-
tion remains unclear. Manufacturers often add
antioxidants to skin lotions, and there is some evi-
dence that fat-soluble vitamins and other oily
(lipophilic) derivatives of vitamins do penetrate the
skin. A 2 percent to 10 percent concentration of
these substances may be needed to be effective;
often, skin preparations contain low amounts.
Some manufacturers incorporate materials in lipo-
somes, microscopic sacs prepared from lipids, to aid
the absorption of a variety of substances. Prepara-
tion of microscopic droplets (called micelles) also
helps materials penetrate the upper dead layers of
skin to reach cells of the dermis. (See also
ACNE.)

Xue, L. “Influence of Dietary Calcium and Vitamin D on
Diet-Induced Epithelial Cell Hyperproliferation in
Mice,” Journal of the National Cancer Institute 91 (1991):
176–181.
skin fold test See FAT FOLD TEST.
skin test See ALLERGY,
FOOD.
small intestine (small bowel) The tube extending
from the stomach to the large intestine (
COLON).
Typically, the small intestine is 1 in. (2.5 cm) in
diameter and 21 ft. (6.35 m) long. It is divided into
three regions; the first 10 inches is called the
DUO-
DENUM
;the JEJUNUM represents the next 8 feet; and
the
ILEUM occupies the lower reaches of the small
intestine. The intestine carries out two distinct func-
tions: It selectively absorbs nutrients and important
materials from food and beverages, and at the same
time, it excludes a vast amount of foreign sub-
stances, ranging from microorganisms and food par-
ticles to pollutants and bacterial by-products. To
carry out its absorptive function, the surface is
highly convoluted and is covered with small projec-
tions about 1 mm high, called
VILLI, giving it a vel-
vet appearance. Within each villus is a capillary
network and lymphatic vessel to aid the uptake and

distribution of nutrients. The surfaces of villi are
lined with absorptive cells; each cell possesses many
microscopic projections called microvilli. The num-
small intestine 583
ber of villi decreases in the ileum; most absorption
occurs in the duodenum and jejunum. The total
surface area of the intestine is huge. If the microvilli
and villi were flattened out, the surface would be
about the size of a tennis court.
The small intestine is the major site of
DIGESTION.
Pancreatic enzymes efficiently digest fat, protein,
and starch. The intestinal lining secretes fluid
(intestinal juice) containing electrolytes (ions) and
mucus to protect the wall of the intestine from
digestive enzymes. The volume is substantial. The
small intestine secretes two to three liters of juice
per day. Most of the ions and water are reabsorbed
and recycled.
Intestinal enzymes complete the final stages of
digestion. They include
MALTASE to digest maltose,
the sugar released from starch digestion;
SUCRASE to
digest
SUCROSE (table sugar); and LACTASE to digest
LACTOSE (milk sugar). A milk intolerance often
reflects
LACTOSE INTOLERANCE that is an impaired
ability to digest lactose due to inadequate lactase.

Undigested lactose passes on to the colon where
bacteria rapidly ferment it, often producing gas,
bloating, and diarrhea. The small intestine also pro-
duces peptidases to degrade small protein frag-
ments to amino acids.
Partially digested food (chyme) moves down the
intestine by localized muscle contraction, creating a
mixing action.
PERISTALSIS refers to the wave-like
contractions moving down the gastrointestinal
tract. Chyme moves at the rate of 1 cm/min; con-
sequently, food remains in the small intestine three
to five hours. The small intestine produces an array
of hormones to regulate digestion.
CHOLECYS-
TOKININ stimulates contraction of the gallbladder to
release bile, and it stimulates pancreatic enzyme
secretion.
SECRETIN reduces gastric and duodenal
motility and promotes bicarbonate secretion by the
pancreas. Gastric inhibitory protein blocks stomach
acid release, while stimulating insulin secretion. To
exclude foreigners, the intestine maintains a phys-
ical barrier. The mucus coating is constantly being
replaced as it is washed away, limiting penetration.
Underlying cells are tightly bonded together to
limit the leakage of unwanted substances into the
body. The movement of food through the digestive
tract and the presence of powerful digestive
enzymes limit uptake of foreign materials. The

major immune barrier is a secreted antibody called
secretory IgA. This defensive protein is secreted by
immune cells embedded within the intestinal wall
and can bind to specific antigens (foreign sub-
stances) and prevent their adhering to the intesti-
nal surface. Like all antibodies, specific types of IgA
are produced against specific antigens.
Cells lining the intestine replenish themselves in
one to two days, thus the nutrient needs of this
rapidly dividing tissue are unusually high. Ample
zinc and the B complex vitamins, especially
FOLIC
ACID
, are essential for maintaining a healthy intes-
tine.
GLUTAMINE helps maintain enterocytes, the
epithelial cells lining the small intestine, while
butyrate (
BUTYRIC ACID) is essential for the help of
colonocytes, lining the colon.
If the intestine become inflamed, it can become
more “leaky” and foreign substances can enter the
body. The influx of foreign materials can trigger
multiple food allergies, joint pain, skin conditions,
and autoimmune disease in which the body’s
defenses attack itself.
LEAKY GUT syndrome can be
caused by alcoholism, overuse of pain medication
(nonsteroidal anti-inflammatory drugs), inadequate
pancreatic output, infection, AIDS, or Crohn’s dis-

ease (ulcerated small intestine), among others. With
chronic constipation, low stomach acid and aging,
colon bacteria may creep upward into the small
intestine, leading to a condition known as bacterial
overgrowth of the small bowel. Symptoms include
sensitivity to starchy food and refined carbohy-
drate—leading to bloating, gas, diarrhea and other
discomfort. Bacterial overgrowth often leads to
maldigestion and to malabsorption of vitamins,
such as
VITAMIN B
12
. Eradicating the offending bac-
teria, while remedying the underlying cause,
together with dietary modification can alleviate this
condition. (See also
AMINO ACID METABOLISM; CAR-
BOHYDRATE METABOLISM; FAT METABOLISM.)
smell The olfactory sense and one of the five basic
senses. Smell is a chemical sense, providing a direct
link with the environment. It evolved primarily to
determine which substances are acceptable. When
molecules escape into the air, they travel up the
nose to a small region of moist tissue called the
olfactory membrane. The sense of smell relies on
the binding of volatile (gaseous) compounds to cell
membranes. Gaseous compounds penetrate the
mucus covering the olfactory cells and bind to hair-
584 smell
like extension (cilia) like tassels. Signals are sent

along a nerve to olfactory bulbs at the base of the
brain, where they radiate out to regions of the brain
concerned with mood, strong emotions, memory,
and thought. There are about 1,000 different recep-
tors or docking sites that are able to recognize some
10,000 different odors. Flavors of foods are often
based on odors rather than mouth (taste) sensa-
tions. Unique flavors usually reflect a combination
of smell and
TASTE. When foods are placed in the
mouth, odor molecules travel to the olfactory neu-
rons up the passage linking the inside of the nose
and throat. A serious loss of smell affects about two
million Americans (a condition known as anosmia).
Most commonly this is a result of allergies, certain
medications, and head injury.
Axel, Richard. “The Molecular Logic of Smell,” Scientific
American 273 (October 1995): 154–159.
sodium The major positively charged ion in body
fluids. Due to their chemical nature, metallic ele-
ments such as sodium exist in solutions and in
compounds as cations, positively charged ions,
where they counterbalance negatively charged
ions, such as
CHLORIDE. Sodium, therefore, func-
tions in maintaining
ELECTROLYTE balance, that is,
the balance between negatively and positively
charged ions and among complex ions such as pro-
teins in the blood. Sodium predominates in the

extracellular fluid, while
POTASSIUM, another
cation, concentrates within cells. Normally, chlo-
ride and sodium tends to leak into cells, while
potassium tends to leak out. Sodium is pumped out
of cells, while potassium is pumped inward by
means of an energy-dependent process called
“active transport.” Maintaining normal cell volume
(and shape) depends on sodium and potassium
pumping. The active transport of sodium and
potassium is a predominant energy-consuming
process of the cells, accounting for a large percent-
age of the total energy expenditure of the body.
Sodium plays a vital role in controlling osmotic
pressure, the pressure that develops between the
blood and cells due to ionic concentration differ-
ences. The total volume of extracellular fluid is
determined by its sodium level, which the body
maintains under tight control by means of the
endocrine and nervous systems. By balancing
charges of negatively charged ions like chloride,
BICARBONATE and phosphate, sodium assists in
maintaining the proper balance between acidic and
alkaline substances (acid-base balance).
Sodium works with potassium in nerve func-
tion. To transmit a nerve impulse, the nerve cell
membrane is temporarily “depolarized”; potassium
temporarily leaks outside and sodium and chloride
leak in. This generates a decrease in electrical po-
tential, which triggers a voltage-dependent in-

crease in sodium penetration. Restoration of the
potential differences to the resting state allows the
impulse to be transmitted as a self-propagating
wave down a nerve cell. Muscles, especially heart
muscles, require an interplay of sodium and potas-
sium by similar mechanisms.
The kidney normally reabsorbs sodium that was
filtered out into the urine to maintain electrolyte
balance. Water follows sodium back into the blood,
thus hormones that increase sodium retention by
the kidney also increase water retention. Sodium
concentration and water balance are controlled by
an interplay of the kidney and several hormones:
When the level of sodium drops, the enzyme
RENIN
is released by the kidney. Renin catalyzes the con-
version of a blood protein to
ANGIOTENSIN. In turn,
this hormone stimulates the adrenal gland to
release
ALDOSTERONE, a hormone that causes the
kidney to increase the rate of sodium reabsorption
from filtered fluid to correct the original sodium
depletion. On the other hand, when dietary
sodium intake is high, the kidney rapidly excretes
sodium. Through the operation of these homeosta-
tic (body balancing) mechanisms, the amount of
sodium excreted is adjusted to equal the amount
consumed. Ninety percent of ingested sodium is
excreted; some is lost through sweat and feces.

Excessive sodium intake and retention can cause
swelling (
EDEMA).
Sources
Most vegetables, fruits, and legumes contain only
low levels of sodium, unless pickled. Although the
U.S.
FDA estimates that processed food contributes
25 percent to 50 percent of the sodium in the typ-
ical U.S. diet, other studies of sample diets indicate
that an estimate of 60 percent to 75 percent is more
realistic. Ninety percent of dietary sodium comes
from sodium chloride (table salt); only 15 percent
sodium 585
of dietary sodium comes from the salt shaker.
There are several explanations for the prevalence
of sodium in foods. Salt is a very inexpensive way
to flavor
PROCESSED FOOD, in place of more expen-
sive herbs and spices. Sometimes companies are
not aware of the sodium content in their products.
The amount of sodium in the same type of food,
produced by different manufacturers, can differ by
50 percent to 300 percent. Salt is also used in
recipes dating to a time when salt was not known
to be potentially harmful.
The only way to detect salty food is by taste,
yet this is an unreliable indicator of sodium con-
tent. For example,
FRENCH FRIES may have only

one-quarter the amount of sodium in an equal
serving (weight) of cherry pie because sugar
masks the taste of salt. Hidden salt occurs in
gelatin desserts, milk shakes, cheese, canned
soups, packaged and frozen dinners, and foods at
fast-food restaurants; in cured ham and bacon,
cured fish, corned beef, smoked herring, and soy
sauce. Processed meat like
BOLOGNA and HOT
DOGS
, tomato KETCHUP, many cold BREAKFAST
CEREALS
, pickled foods, and salad dressings pro-
vide high levels of sodium. Sodium occurs in
other food additives such as baking soda and
sodium aluminum sulfate (in baked goods),
sodium caseinate (a milk product), sodium phos-
phate (the major contributor of sodium in
cheese), sodium nitrite and sodium benzoate
(preservatives), and
MONOSODIUM GLUTAMATE (fla-
vor enhancer).
LAXATIVES and ANTACIDS can
account for a large percentage of sodium for some
people, especially elderly persons. Human milk
contains 161 mg of sodium per liter, while cow’s
milk provides 483 mg per liter; therefore, cow’s
milk provides considerably more sodium.
Soft water contains high levels of sodium. The
amount depends upon the hardness of natural

water. A glass of tap water usually contains less than
3 mg of sodium. However, salt from the de-icing of
roads and ion exchange resins can raise sodium
levels in inland areas. Sodium from seawater can
leach into the water supplies of coastal areas.
Requirements
There is no
RECOMMENDED DIETARY ALLOWANCE
(RDA) for sodium. A safe and adequate level was
proposed by the Food and Nutrition Board as
1,100 to 3,300 mg per day in 1980. The 1989 RDA
recommendations list the minimum requirements
for healthy persons (adults 18 or older) as 500 mg
of sodium daily. The sodium requirements of
infants and small children are estimated to be
about 58 mg daily. The amount of sodium
required to maintain sodium equilibrium for most
adults may be less than 200 mg under normal cir-
cumstances, equivalent to one-tenth a teaspoon of
salt per day. The overall consensus is that Ameri-
cans generally consume too much salt. The typical
adult intake is 6 g to 25 g of salt, with a mean of
10 g/day, equivalent to 4 g of sodium, 20 times as
much as the listed minimum. The maximum rec-
ommended daily intake of sodium chloride is 6 g
(2.4 g).
Few people in the United States are sodium defi-
cient. Relatively heavy sweating is now associated
with a need for extra salt, and the primary concern
should be fluid replacement. Athletes undergoing

strenuous physical exercise do not need salt until
they have lost approximately three quarts of water
by sweating. The kidney adapts to sodium losses in
hot weather, so that less sodium, hence less water,
is excreted. One typical meal will more than make
up for sodium lost in sweat through moderate
exercise. Chronic diarrhea, kidney disease, or other
medical conditions can limit the body’s ability to
retain sodium and thus increase sodium require-
ments. Excessive sodium can be toxic to infants
because their kidneys are not fully developed; it
may also be toxic to those with kidney disease or
those who have adjusted to a chronically low-
sodium diet.
Sodium and High Blood Pressure
Sodium has been linked to high blood pressure
(
HYPERTENSION) in extensive studies spanning
decades. Perhaps 10 percent to 20 percent of Amer-
icans experience increased blood pressure when
they eat excess sodium. High blood pressure
increases the risk of
STROKE, HEART ATTACK, and kid-
ney disease. Worldwide, a low sodium intake
matches a lowered risk of hypertension. Certainly
OBESITY, genetic makeup, lack of exercise, and
excessive alcohol are risk factor for developing
hypertension. Salt sensitivity increases with age. As
586 sodium
people grow older, their kidneys excrete less

sodium, and an increased sodium intake is more
likely to raise blood pressure in susceptible people.
Cutting back on salt intake may lower blood pres-
sure by a small amount; however, even relatively
small decreases in blood pressure readings could
mean a significant decreases in the risk of death
due to coronary heart disease. Excessive sodium
increases urinary losses of calcium and can con-
tribute to the risk of osteoporosis. Additionally, a
high-salt diet is a dominant risk factor for stomach
cancer. Governmental dietary guidelines recom-
mend moderate sodium consumption, and individ-
uals with hypertension or who have a family
history of hypertension may be advised to curtail
sodium consumption.
To cut back on salt, do not add salt to foods. Sea-
son with herbs or sauces instead. Cut back on
processed, convenience foods. Read food labels to
determine the sodium content and avoid foods
with high sodium. Do not take salt tablets without
consulting a doctor. Reducing high blood pressure
can mean, in addition to cutting back on sodium,
limiting alcohol consumption to one or two drinks
per day; engaging in regular aerobic exercise; get-
ting enough calcium, potassium, and magnesium;
and losing weight.
Sodium on Food Labels
Sodium must be listed on the label of any foods
that list nutritional content, and on those that
make nutritional claims as being “low fat” or

“enriched.” (Exempt foods are those made with
meat or poultry.)
• “Sodium free” means less than 5 mg of sodium
per serving.
• “Very low sodium” foods contain at most 140 mg
per serving.
• “Low sodium” foods contain at most 140 mg per
serving.
• “Reduced sodium” means the food has been
processed to reduce normal sodium levels by at
least 75 percent.
• “No sodium” and “no salt” alternatives: Several
cold breakfast cereals, canned vegetables, and
herbal salt substitutes have been introduced to
meet consumer demands.
SODIUM CONTENT OF COMMON FOODS
Food Sodium (mg) per 100 g (3 oz.)
Canadian bacon 2,555
Green olives 2,400
Corned beef 1,740
Cheese 1,430
Bologna 1,300
Cold cereal (oats) 1,267
Cured ham 1,100
Wheatflake cereal 1,032
Potato chips 1,000
Sausage 958
(See also FOOD ADDITIVES; MINERALS.)
sodium alginate See
ALGINATE.

sodium ascorbate See VITAMIN C
.
sodium benzoate A food preservative that
retards growth of microorganisms under acidic
conditions. Foods and beverages can contain up to
0.1 percent sodium benzoate. Soft drinks, salad
dressing, and fruit juices often contain this preser-
vative. Sodium benzoate also occurs naturally in
vegetables and fruit, for example, in prunes and
cranberries. Sodium benzoate is a product of
metabolism as well. Extensive studies indicate it is
a safe additive.
sodium chloride See SODIUM.
sodium erythroborate See ERYTHROBORIC ACID
.
sodium nitrate See NITRATE.
sodium nitrite See NITRITE.
soft drinks Carbonated, nonalcoholic beverages
that contain dissolved
CARBON DIOXIDE (carbona-
tion), sweeteners, flavoring agents, edible acids,
and food coloring. Soft drink consumption in the
United States has doubled since 1974. Increased
soft drink consumption means increased consump-
tion of
PHOSPHOROUS, ARTIFICIAL FOOD COLORS, and
ARTIFICIAL SWEETENERS
, and sugar. In contrast,
water contains none of these additives.
soft drinks 587

In 2001 a team of U.S. researchers published an
article in the British medical journal Lancet linking
soft drink consumption among children and ado-
lescents with the rise in obesity rates among U.S.
teens. The researchers found that for every addi-
tional serving of soft drink consumed each day, the
risk of becoming obese increased by 50 percent.
Some researchers also blame increased soft drink
consumption with a rise in calcium deficiency
among young people. According to the American
Academy of Orthopedic Surgeons, children from
birth to age 11 and teenage boys consume only half
the amount of calcium they need daily. Teenage
girls are meeting only 14 percent to 20 percent of
their daily calcium requirements.
STANDARDS OF IDENTITY define certain aspects of
the composition of foods and beverages. Soft drinks
are classified as soda water and must contain more
carbon dioxide than can be absorbed at normal air
pressure. Alcohol content, if contributed by a fla-
voring agent, cannot exceed 0.5 percent of the
weight.
CAFFEINE can be added to any soda water to
a final concentration of 0.02 percent by weight.
Optional ingredients include sweeteners (synthetic
and nonsynthetic), edible acids, flavors, colors,
preservatives, emulsifying agents to prevent ingre-
dients from separating, thickening agents to create
cloudiness and “mouth feel,” and foaming agents.
SUCROSE (table sugar) is among the most common

NATURAL SWEETENERS used in soft drinks. Also ap-
proved are dextrose (
GLUCOSE), INVERT SUGAR, FRUC-
TOSE, CORN SYRUP, high FRUCTOSE CORN SYRUP (now a
general soft drink sweetener), and glucose syrup.
The artificial sweetener
ASPARTAME is used exten-
sively in diet soft drinks.
SACCHARIN, another
noncaloric sweetener, is used in soft drinks as well.
Phosphoric acid is added to acidify soft drinks. Other
acids used in soft drinks include
ACETIC ACID, fumaric
acid,
LACTIC ACID, and gluconic acid, an acid of glu-
cose. The phosphate in soft drinks increases the over-
all phosphate consumption. This can be detrimental
because a high phosphate intake is linked to an over-
active thyroid gland and bone loss (
OSTEOPOROSIS).
Furthermore, drinking large amounts of diet soda
(eight to 10 cans a day) is a cause of tooth erosion.
Types of Soft Drinks
Colas These contain extract of the cola nut and
caffeine. The coloring agent is typically caramel
(brown sugar) and the sugar content can be 11 per-
cent to 13 percent.
Orange Soft Drinks Artificial colors, orange oil,
or orange juice may be added. The sugar content
resembles colas and the edible acid is usually

CITRIC
ACID
. These are not substitutes for orange juice.
Ginger Ale Ginger root extract, ginger, and
lime oil may be the flavoring agents in these soft
drinks. Caramel may be used as a coloring and cit-
ric acid is the edible acid. The sugar content ranges
from 7 percent to 11 percent.
Grape-flavor Soft Drinks Synthetic grape fla-
vor or grape juice may be used in flavoring and
artificial coloring is used. The sugar content is gen-
erally between 11 percent and 13 percent, and the
edible acid is
TARTARIC ACID. (See also CONVENIENCE
FOOD
; EMPTY CALORIES; JUNK FOOD.)
Ludwig, David S. et al. “Relation Between Consumption
of Sugar-Sweetened Drinks and Childhood Obesity: A
Prospective, Observational Analysis,” Lancet 357
(2001): 505–508.
Wyshak, G. “Teenaged Girls Carbonated Beverage Con-
sumption, and Bone Fractures,” Archives of Pediatric
Adolescent Medicine 154 (2000): 610–613.
solanine An
ALKALOID that acts as a plant’s defen-
sive agent against insects. Solanine is found in very
low levels in apples, tomatoes, eggplant, and sugar
beets.
POTATOES contain the highest concentration of
solanine, which contributes to their characteristic

flavor. Solanine acts as a nerve poison by blocking
the action of
NEUROTRANSMITTERS, brain chemicals
required for transmitting nerve impulses. Most
American-growth varieties of potatoes contain low
levels of solanine, so that a person would have to
consume 4.5 lb. (2 kg) of unbruised, nonsprouted
potatoes to ingest 200 mg of solanine, a dose that
could cause drowsiness, cramps, neck itchiness and
DIARRHEA. However, the content of solanine in pota-
toes increases dramatically with bruising or sprout-
ing, or when the skin turns green due to exposure to
too much sunlight after harvest. Damaged or green-
skinned potatoes should be discarded for this reason.
somatotropin See MEAT CONTAMINANTS.
sorbic acid (potassium sorbate) A food PRESERV-
ATIVE used to inhibit the growth of molds, yeast,
588 solanine
and fungi, but not bacteria. Sorbic acid is used in
CHEESE manufacture, allowing bacteria to ferment
milk products while inhibiting yeast and mold
growth. Because sorbic acid is effective over a wide
range of pH, it is used in a variety of foods, includ-
ing
MAYONNAISE, cake, MARGARINE
, dried fruit, SOFT
DRINKS
, and syrup at concentrations up to 0.03 per-
cent. It breaks down at high temperature and can-
not be pasteurized. The body metabolizes sorbic

acid like a fatty acid; consequently, it is an energy
source. It is considered a safe
FOOD ADDITIVE.
sorbitol (hexitol) A naturally occurring sugar
ALCOHOL
. Sorbitol is 60 percent as sweet as SUCROSE
(table sugar) although it is not a carbohydrate. It
is used in chewing gum, confections, icing, food
toppings, meat products, milk products, and bever-
ages. It reduces the rate of sugar crystal formation,
maintains moisture, and sequesters (binds) food
ingredients.
Sorbitol occurs in many fruits, including berries,
CHERRIES, PEARS, PLUMS, and APPLES and in SEAWEED.
Both apple juice and pear juice contain a high con-
centration. Sorbitol in apple juice is not absorbed
well by infants and small children; it can ferment in
the large intestine, producing gas, cramps, and
DIARRHEA. Large doses of sorbitol (50 g) can cause
diarrhea in adults.
Sorbitol is synthesized by hydrogenation of the
simple sugar
GLUCOSE (dextrose). Sorbitol contains
the same number of four calories per gram as car-
bohydrate and is burned completely to carbon
dioxide. However, it does not form glucose in the
body, thus it does not raise
BLOOD SUGAR. There-
fore, sorbitol is used as a sweetener in certain
dietetic foods. Sorbitol-containing foods and chew-

ing gums are not calorie-free, although they carry
a “sugarless” or “sugar free” label. Sorbitol forma-
tion in cells occurs as a side effect of
DIABETES MEL-
LITUS. Since it cannot leak out of cells, sorbitol can
gradually accumulate, leading eventually to
osmotic imbalances and tissue damage. (See also
ARTIFICIAL SWEETENERS; FOOD ADDITIVES; NATURAL
SWEETENERS
.)
sorghum (Sorghum vulgare; Guinea corn, kaffir
corn) A major cereal
GRAIN that is a staple in
Africa and Asia. Sorghum ranks in the top five
most important cereal grains worldwide. Well
adapted to climates too hot and dry for
CORN and
WHEAT, sorghum has been grown in regions of Af-
rica and Asia since 2000
B.C. The People’s Republic
of China, the United States, India, and Argentina
provide much of the world’s production. In the
United States sorghum is used primarily as animal
fodder. Only 1 percent to 2 percent of U.S. sor-
ghum is used for food or alcoholic fermentation.
Though related to
MILLET, nutritionally sorghum
resembles corn. Both grains are deficient in the
essential
AMINO ACID, LYSINE

. In Africa and Asia,
sorghum is used as a flour or a porridge. Sweet
sorghum is used to make an unrefined syrup, more
sour than molasses. As with all refined sweeteners,
the amounts are too low to be reliable sources of
minerals or B complex vitamins. The nutrient
content of 1 cup (3 oz., 100 g) of sorghum is: 366
calories; protein, 11.0 g; carbohydrate, 73 g; fat, 3.3
g; thiamin, 0.38 mg; riboflavin, 0.15 mg; niacin,
3.9 mg.
soul food A cuisine originating in the southern
United States, where, in the antebellum era,
slaves developed eating practices from their West
African roots. Soul food has been modified by
later generations, but typically includes collard
greens, mustard greens, turnip greens, fried
chicken, sweet potato pie, and corn bread. Tradi-
tionally, these high-salt, high-fat foods pose a
potential health problem, especially among blacks
who are experiencing an epidemic of high blood
pressure in the United States. As with other eth-
nic dishes, the use of spices and herbs for season-
ing is recommended to cut down on salt. Recipes
can be adapted to use less
FAT in cooking, such as
the substitution of
VEGETABLE OIL for LARD to
reduce consumption of
SATURATED FAT. Modifica-
tions can help make soul food dishes nutritious

and heart healthy, while still tasty and appetizing.
(See also
DIETARY GUIDELINES FOR AMERICANS; FOOD
PYRAMID
; HYPERTENSION.)
soybean (Glycine max; soya, soy pea) The oil-
rich seed of a bushy
LEGUME; a food staple in Asia.
The soybean originated in eastern Asia and was
cultivated in ancient China. American and Cana-
dian cooperative agricultural projects in the 1930s
soybean 589