Structure function nutrition

Structure-Function
Lecture 106 Nutrition I
Basis for Nutrient Requirements
Arline McDonald, Ph.D.
Department of Preventive
Medicine

December 7,

Nutrition

1


Power of nutriment reaches to bone and to
all parts of bone, to sinew, to vein, to
artery, to muscle, to membrane, to flesh,
fat, blood, phlegm, marrow, brain, spinal
marrow, the intestines, and all their parts; it
reaches also to heat, breath, moisture.
--Hippocrates (460-377 B.C.)

December 7,

Nutrition

2


Nutrition Education Roadmap
Northwestern University Medical School

N u t r it io n
P r in c ip le s
W e lln e s s

P r e v e n t io n /
P r im a r y C a r e

T h e r a p e u t ic s /
C r it ic a l C a r e

M a n a g e c h a n g in g
n u t r it io n n e e d s
o v e r t h e life c y c le

R is k fa c t o r
m a n a g e m e n t w it h
d ie t a r y m o d ific a t io n s

P r im a r y o r a d ju n c t
t h e r a p y w it h
s p e c ific g o a ls

M1
Structure/Function

December 7,

M2

M3-M4

Scientific Basis of Clinical Clerkships
Medicine

Nutrition

3


M1: Structure/Function
Developmental
Stage

Age-specific
physiologic
and metabolic
priorities

December 7,

C o u rs e
O r g a n iz a t io n
and
E m p h a s is

Nutritional
Emphasis

M a te rn a l
N u t r it io n

F e ta l g ro w th
L a c t a t io n

I n fa n t
N u t r it io n

W e ig h t g a in
L in e a r g r o w t h

C h ild h o o d
N u t r it io n

G ro w th
D e v e lo p m e n t

A d o le s c e n t
N u t r it io n

M a t u r a t io n

A d u lt
N u t r it io n

H e a lt h
m a in t e n a n c e

G e r ia t r ic
N u t r it io n

A g in g

Nutrition

Nutrient
requirements
to support these
priorities

4


Basis for Nutrient
Requirements
Supporting
nutrient
Dietary
requirements

Reference Intakes (DRI)
Determine
nutritional
priorities &
risk of
deficiencies

Physiological
Activities
Metabolic Processes

Age or Developmental Stage
December 7,

Nutrition

Defines
structural
& functional
needs

5


Nutrient Characteristics
• absolute requirement to support life
• must be obtained from exogenous sources
– despite ability for endogenous synthesis

• presence in fetal tissue
• Hormonal mechanism for regulation of
reserves
• compromised metabolism/clinical
symptoms associated with deficient intake
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Nutrition

6

Essential Nutrients
Carbohydrate glucose; dietary fiber
linoleic acid (-6); linolenic acid (-3)

Lipid
Protein

Vitamins

tryptophan, threonine, histidine, leucine, lysine, isoleucine,
methionine, valine, phenylalanine
thiamin, riboflavin, niacin, pyridoxine (B6) folic acid, cobalamin
(B12), pantothenic acid, biotin, ascorbic acid (C); retinol (A),
cholecalciferol (D), tocopherol (E), phylloquinone (K)

Minerals

calcium, phosphorus, magnesium, sulfur;sodium, potassium,
chlorine; iron, zinc, copper, iodine, chromium, selenium,
manganese, fluorine, molybdenum

Energy

kilocalories or kilojoules

Fluid

water

December 7,

Nutrition

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Cellular Roles of Nutrients
• Provide energy
• Incorporated into cellular
compounds
• Provide structural
elements
• Support mechanical,
chemical, electrical
processes

December 7,

Nutrition

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Molecular Roles of Nutrients
• regulate gene expression
• protect, function, and
support catalytic activities
of enzymes
• demonstrate hormone-like
activity

• facilitate hormone
receptor binding and
activity
• support and regulate
immune system activities

December 7,

Nutrition

9


Examples of Structural and
Functional Roles of Nutrients
Role

Structure

Function

Enzymes/
Coenzymes

Zn, Fe, pyridoxal vitamin C
phosphate, NAD,
FAD

Regulation of
cell processes

polyunsaturated
fatty acids,
amino acids

Ca, Na, K,

Tissue
synthesis/
repair

amino acids, Ca,
P

Zn, vitamin C, Cu, Fe,
vitamin D, Mg

Protection

vitamin E,
amino acids

vitamin C, Se, Fe,
polyunsaturated fatty
acids

Nutrition
Fe,
Cu, P, Mg

10
niacin, riboflavin,

December
Energy

7,


Nutrient Requirements*
D ie ta r y R e fe r e n c e In ta k e s
(D R I)
A d e q u a te
In ta k e
(A I)

E s tim a te d A v e r a g e
R e q u ir e m e n t
(E A R )

Recom m ended
D ie ta r y A llo w a n c e s
(R D A )

T o le r a b le U p p e r
In ta k e L e v e l
(U I)

E x p e r im e n ta lly
D e te r m in e d

A p p r o x im a tio n

R e q u ir e m e n t fo r
50% of
H e a lth y
P o p u la tio n

R e q u ir e m e n t fo r
9 7 -9 8 % o f
H e a lth y
P o p u la tio n

Level
A s s o c ia te d w ith
A d v e rs e o r
T o x ic E ffe c ts

*as defined by the Food and Nutrition Board, National
Academy of Sciences and the Institute of Medicine (1998)

December 7,

Nutrition

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Physiological Function

Effects of Nutrient Intakes on

Physiological Function
100%
Optimal
75%
50%

Marginal

Marginal

25%
Excess

0%
Deficiency

Nutrient Intake

Adapted from: The Surgeon General’s Report on Nutrition and Health,
1984.

December 7,

Nutrition

12


Identification of Nutrient Deficiencies
 Classic Symptoms

–
–
–
–
–
–
–
–
–

–
–
–
–
–

energy
protein
fluid
vitamin C
folate
B-complex
iron
vitamin A
vitamin D

December 7,

 Biochemical Signs
copper

vitamin B12
vitamin E
vitamin K
zinc

 No well-defined signs
 selenium
 magnesium
 calcium

Nutrition

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A
du

lt
h

oo

d

In
Ea fan
rl cy
La y
t e Ch

Ch ild
Ad
ild ho
ho o d
ol
es
od
ce
nc
e

Age and Developmental Stages that
Define Nutrient Requirements

Early
Age
0 14 11
yrs

18

e
G

Middle
35

Late
51

Pregnancy/Lactation

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Nutrition

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7
0

i
r
at
i
r

c


Nutrient Needs By Life Stage
Life Stage

Age (yrs)

Nutritional Considerations

Infancy

0-0.5

0.5-1

Term/Preterm Birth
Age/Weight
Growth

Early
Childhood

1-3

Growth and Immunity

Late
Childhood

4-10

Growth, Immunity, Activity

Adolescence

11-18

Gender Differences, Growth
Spurt, Hormonal Changes

Adulthood

19-25; 26-51

51-70; 70+

Inactivity, Disease Risk
Factors, Menopausal Status

December 7,

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Nutrient Needs By Life Stage

Life Stage

Time Frame

Nutritional Considerations

Pregnancy

2nd and 3rd
trimester

Pre-pregnancy body weight
and nutritional status; age;
presence of disease

Lactation

1-6 months
6-12 months

Milk volume and nutrient
composition

December 7,

Nutrition

16


Energy Requirements By Age
Light to Moderate Activity

kcal/kg body weight

120
100
80

108
98

102
90
70

60

50
37.5

40

30

20

0-6 mos
6-12 mos
1-3 yrs
4-6 yrs
7-10 yrs
11-18 yrs*
21-50 yrs*
51+ yrs

0

* Average for males and females
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Protein Requirements by Age

g/ kg body weight

2.5

2.2

2

0-6 mos
6-12 mos
1-3 yrs
4-6 yrs
7-10 yrs
11-18 yrs*
Adult*

1.6
1.5

1.2

1.1

1

1

0.9

0.8

0.5
0

* Average for males and females
December 7,

Nutrition

18


Contribution of Basal Metabolism to
Total Energy Requirements
basal metabolism
activity
specific dynamic effect

10%

30%

December 7,

muscle mass
growth
pregnancy
lactation

infection
trauma
Nutrition

60%

19


Sources of Metabolic Fuel
• Carbohydrate (Glucose)
Kcal/ g

– Preferred fuel
– Highest energy yield/mole
– Supports fat oxidation
4

7

EtOH

– High energy density
– Storage fuel

PRO
CHO 4

FAT

• Alcohol (Acetate)
– Metabolic fate same as fat

• Protein (Amino Acids)
– Not efficiently utilized
– Conserved for other roles

9

December 7,

• Fatty acids (Fat)

Nutrition

20


Vitamin Requirements as a Function
of Energy Intake
0.59

Thiamin
Riboflavin
Niacin

0.054
0.045

Adult

Women
2300 kcal
0.65

Thiamin
Riboflavin
Niacin

0.058
0.052
0

Adult Men
2900 kcal

0.2

0.4

0.6

0.8

mg/ 100 kcal

December 7,

Nutrition

21

Tissue Synthesis: Growth,
Replacement, Repair
New Tissue
Scar

e,
F
C,

Cu

Tissue-specific needs

no
i
am
Prote
,
y
in S y
rg s , B 6
nthe
e
sisEn cid
a

Nuc
leic

Acid
Syn
thes
is

December 7,

Nutrition

B 12
,
te
a
l
Fo
,
Fe
,
Zn

22


Erythropoiesis
Vitamin C
Amino acids
B6, Cu, Fe

Heme

Hemoglobin

Vitamin E
Cell replication
Folate, B12

December 7,

Nutrition

23


Cognitive Development and
Neurological Function
B12
Fe, B6
Myelin Synthesis

DOPA

C22 Fatty
Acids

Vitamin E

December 7,

Nutrition

24


Skeletal Development & Remodeling
Vitamin K
Ca, P
Magnesium, Vitamin D
Vitamin A

Vitamin C, Cu, Fe

December 7,

Nutrition

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