HUMAN BIOLOGY

214 Chapter 11

Vitamins, minerals, and phytochemicals

n Vitamins and minerals are essential for normal

body functioning.

Vitamins are organic substances with essential functions

in metabolism (Table 11.4). No other substances can play

their roles. In the course of evolution, animal cells have

lost the ability to synthesize these substances, so we must

obtain vitamins from food.

Each vitamin has specific metabolic functions. Many

chemical reactions use several types, and the absence of

one affects the functions of others.

Minerals are inorganic substances that also are essen-

tial because no other substance can serve their metabolic

functions (Table 11.5). As examples, cells need iron for their

electron transport chains, red blood

cells can’t function without iron in

hemoglobin (the oxygen-carrying

pigment in blood), and neurons

require sodium and potassium.

People who are in good health

and who eat a balanced diet of whole

11.13

A vitamin-rich meal

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minerals Inorganic sub-
stances with an essential
role in metabolism.

vitamins Organic sub-
stances with an essential
role in metabolism.

foods probably get the vitamins and minerals they need.

Yet nearly half of Americans regularly “self-prescribe”

vitamin and mineral supplements, including several touted

as antioxidants effective in slowing normal aging and

preventing cancer. Is this a sensible strategy? A growing

Vitamin Main Dietary Sources Main Functions Symptoms of Deficiency

Fat-Soluble Vitamins

A Orange fruits and vegetables, Component of visual pigments; Night blindness, skin problems

leafy greens, egg yolk maintains epithelia

D Fatty fish, egg yolk Aids uptake and use of calcium Weak/soft bones, rickets in children

E Nuts, seeds, vegetable oils Antioxidant, aids fat absorption; Muscle weakness, nerve damage

helps maintain cell membranes

K Green vegetables Needed for blood clotting Impaired blood clotting

Water-Soluble Vitamins

B 1 (thiamin) Meats, nuts, legumes Coenzyme in carbohydrate metabolism Beri beri (neurological and heart problems)

B 2 Meats, eggs, nuts, milk, Component of the coenzyme FAD Anemia, sores in mouth, sore throat

(riboflavin) green vegetables

B 3 (niacin) Meats, fish, dairy products, Component of the coenzyme NAD Skin and mucous membrane sores,

nuts, legumes gut pain, diarrhea, psychosis, dementia

B 6 Meats, fish, starchy vegetables, Coenzyme in protein metabolism Anemia, sores on lips, depression,

noncitrus fruits impaired immune function

B 7 (biotin) Meats, fish, nuts, legumes, Coenzyme in many reactions Hair loss, dry skin, dry eyes, fatigue,

whole grains insomnia, depression

B 9 (folic acid) Meats, fruits, green vegetables, Coenzyme in nucleic acid synthesis Anemia, sores in mouth; deficiency during

whole grains and amino acid metabolism pregnancy causes neurological birth defects

B 12 Meats, seafood, dairy products Coenzyme in amino acid synthesis Anemia, fatigue, neurological problems

C (ascorbic Fruits (especially citrus) Required for collagen synthesis, Scurvy (anemia, bleeding gums, impaired

acid) and vegetables antioxidant wound healing, swollen joints)

Table 11.4 Major Vitamins: Sources, Functions, and Effects of Deficiencies or Excesses*

*Guidelines for appropriate daily intakes are being worked out by the Food and Drug Administration.

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