Ganong's Review of Medical Physiology, 23rd Edition

CHAPTER 27Digestion, Absorption, & Nutritional Principles 465

TABLE 27–4 Vitamins essential or probably essential to human nutrition.a

Vitamin Action Deficiency Symptoms Sources Chemistry

A (A 1 , A 2 ) Constituents of visual pig-

ments (see Chapter 12: Vi-

sion); necessary for fetal

development and for cell

development throughout

life

Night blindness, dry

skin

Yellow vegeta-

bles and fruit

B complex

Thiamin

(vitamin B 1 )

Cofactor in decarboxyla-

tions

Beriberi, neuritis Liver, unrefined

cereal grains

Riboflavin

(vitamin B 2 )

Constituent of flavopro-

teins

Glossitis, cheilosis Liver, milk

Niacin Constituent of NAD+ and

NADP+

Pellagra Yeast, lean meat,

liver

Pyridoxine

(vitamin B 6 )

Forms prosthetic group

of certain decarboxylases

and transaminases. Con-

verted in body into pyri-

doxal phosphate and

pyridoxamine phosphate

Convulsions, hyperirri-

tability

Yeast, wheat,

corn, liver

Pantothenic

acid

Constituent of CoA Dermatitis, enteritis, al-

opecia, adrenal insuffi-

ciency

Eggs, liver, yeast

Biotin Catalyzes CO 2 “fixation”

(in fatty acid synthesis,

etc)

Dermatitis, enteritis Egg yolk, liver, to-

matoes

Folates (folic

acid) and relat-

ed compounds

Coenzymes for “1-car-

bon” transfer; involved in

methylating reactions

Sprue, anemia. Neural

tube defects in children

born to folate-deficient

women

Leafy green vege-

tables

Cyanocobal-

amin (vitamin

B 12 )

Coenzyme in amino acid

metabolism. Stimulates

erythropoiesis

Pernicious anemia (see

Chapter 26: Overview

of Gastrointestinal

Function & Regulation)

Liver, meat, eggs,

milk

Complex of four substituted pyrrole rings around a

cobalt atom (see Chapter 26: Overview of Gastro-

intestinal Function & Regulation)

C Maintains prosthetic

metal ions in their re-

duced form; scavenges

free radicals

Scurvy Citrus fruits, leafy

green vegetables

(continued)

Vitamin A 1 alcohol (retinol).

C

C

H 2

C

C(CH

CH 3

CH C

CH 3

H 2 C

H 2 C

H 3 CCH 3

CH) 2 CH 2 OH

+N

S

N

N

CH 2

CH 3

NH 2

CH 3 CH 2 CH 2 OH

C

C

H

H

C

C

C

3 C CH

H 3 C

CH 2 (CHOH) 3 CH 2 OH

N

N

C

C N

C

O

NH

CO

COOH

N

Can be synthesized in

body from tryptophan.

HO CH 2 OH

H 3 C

N

CH 2 OH

HO C C

H

H

CH 3

CH 3

CCN CH 2 CH 2 COOH

H

H

OH

O

O

C

C

H NH

C

N

H H

H 2 C S CH(CH 2 ) 4 COOH

Folic acid

NH 2

OH

N

NN

CH (^2) N
H
C
O
CHNH
COOH
CH 2
CH 2
HOOC
NH
C O CO
H
OH
CHO H
CH 2 OH
CC
Ascorbic acid (synthesized in most
mammals except guinea pigs and
primates, including humans).
OH