Vitamin and phytochemicals

Vitamins and
Lecture 7
Units 20, 21

Phytochemicals


Vitamins: General
Info
Organic compounds
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Micro nutrients--need in small amounts
Function as regulators--allow metabolic
reactions to occur
Have no calories
Excess may be toxic, does not enhance


Classification
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Water Soluble (9) – B1, B2, B3, B6, B12,
folate, biotin, pantothenic acid, & C
Little storage, Excess excreted in urine

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Fat Soluble (4) – A D E & K
Absorbed with fat

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Excess may be toxic


Causes of Deficiency
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Little variety in diet--insufficient intake
Poor
of vitamin
Increased requirement for vitamin

illness
 competing drugs
 growth, etc.
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Vitamin deficiency not big US problem

Thiamin, Riboflavin &
Niacin
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B 1, B 2, B 3
Function: as
Deficiencies:
B1-beriberi; B2-ariboflvinosis; B3-pellagra
Must be added to enriched flour
Source: whole grains, enriched products
 Thiamin (B ) : pork
1
 Riboflavin (B ) : milk
2
 Niacin (B ) : protein foods
3


Pyridoxine (B6)
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Function: protein and amino acid
metabolism;
neural function;
conversion of tryptophan to niacin
Source: protein foods (meats, milk)
Whole grains, fortified cold cereals
Deficiency: anemia, muscle weakness


Folic Acid -- Folacin
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Functions: production of red blood cells;
protein synthesis
Prevents neural tube birth defects;
maintains normal homocysteine level
Current recommendation(
µg):
Women should take folic acid supplement
when want to become pregnant
Food sources: “foliage” vegetables,
enriched bread & grain products

Vitamin(B12) Cobalamin
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Function: red blood cell production
Nerve tissue production
Deficiency: pernicious anemia;
neurological disorders
Source: animal products only
should take supplement
Absorption can be problem in elderly-take B12 shots


Vitamin C - Ascorbic
Acid
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Functions:
 Collagen formation
 Antioxidant
 Fights infection,

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↑ absorption of Fe
Deficiency:
Sources: citrus, kiwi, green peppers,
cabbage family, potato


Biotin & Pantothenic
Acid
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Functions: various metabolic reactions
Biotin – glycogen, fat, protein synthesis
PA – energy production
No “classical”
A variety of foods will provide enough


Vitamin A
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Retinol

“pre-formed” vit A
 Animal sources only
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Beta carotene

“precursor” changed to
at
absorption
 Plant sources--bright orange color
 Anti-oxidant function
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Functions of Vitamin A
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Prevent night blindness
Bone growth
Healthy epithelial cells (not dry)

skin
 mucous membranes
 Deficiency: xerophthalmia causes
; susceptible to infection
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Vitamin A Toxicity

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Concept of optimum intake

Too little → deficiency
 Too much → toxicity
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Birth defects; liver damage; hair loss
Toxic only by
, not food
Vit A is toxic but not carotene


Vitamin A Food Sources
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Precursor carotene from plants
 bright orange: carrots, cantaloupe,
pumpkin, sweet potato
 dark green: spinach, broccoli
Preformed vitamin from animals
 liver - richest source
 whole or fortified skim milk

 egg yolk


Vitamin D - Cholecalciferol
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Function: ↑ blood Calcium (↑ absorption)
Deficiency: Rickets in children;
loss of Ca leading osteoporosis in adults
Toxic in excess –
Few food sources
 Fortified milk, butter/margarine
 Liver
Sunlight activates precursor in skin


Vitamin K
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Function: blood “K”oagulation
Synthesized by
in GI tract
Deficiency: abnormal blood clot;bruise
easily
 Hemorrhage in infants b/c little synthesis
 Long term use of antibiotics
Toxic only with excess synthetic
supplements
Food sources--leafy green veg


Vitamin E -- Tocopherol
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Fertility function only in
Function as anti-oxidant
 Foods: protects against rancidity
 Body: protects from “free radical
damage” to cells and tissues;
prevents artery plaque formation
Food sources
 Nuts, seeds, wheat germ, whole grain
 Veg oil, marg, mayo & salad dressing

Antioxidants
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Beta-carotene
Vit E
Vit
Selenium
PUFA in our cell membranes
 double bonds susceptible to oxidation
 free radical + FA
oxidized
FA(reactive)
 anti oxidants get oxidized instead


Phytochemicals
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Plant chemicals

Not essential nutrients
Rich in veg & fruits known to be
protective against heart disease,
cancers
Most are beneficial but some are
Supplements have no proof of benefit


Examples of
Phytochemicals
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Indoles : cruciferous veggies
Terpenes: orange, grapefruit
Flavonoids: apple, celery, green tea
Allicin: garlic, onions, leeks
Phytoestrogens: soybean, soyfoods
Isoprenoids: grains, fruits, veggies


Genetically Modified
Foods
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Biologically altering food composition
Enhances
Improves
Herbicide and insect resistance
Concerns about safety of environment
Controversies: unscientific and
emotionally driven speculations