HUMAN BIOLOGY

DiGestioN aND NUtritioN 215

What are vitamins and minerals?

• Vitamins and minerals are substances that have specific
  metabolic functions no other nutrients can serve.


• The naturally occurring plant substances called phytochemicals
  may reduce the risk of heart disease and certain cancers.

taKe-Home message

phytochemicals Plant

molecules that are not an

essential part of the human

diet but that may reduce the

risk of certain disorders.

body of scientific evidence suggests that the decision to
take supplemental vitamins or minerals should be tailored
to personal circumstances and planned with the help of a
physician. One reason for caution is that excessive amounts
of many vitamins and minerals can be useless or even
harmful. For example, very large doses of vitamin E appear
not to protect against cancer, nor do they extend lifespan
generally. Large doses of the fat-soluble vitamins D and A
can build up in tissues, especially in the liver, and interfere
with normal metabolism. High doses of vitamin C can pro-
duce digestive upsets.
You may remember from the introduction to Chapter 2
that a healthy diet should provide various phytochemicals,
also called phytonutrients. These compounds, which
occur in various plants, are thought to reduce the risk of
certain cancers and other disorders. Examples include

the lycopene in tomatoes, flavo-

noids in yellow/orange fruits such

as cantaloupe and citrus fruits,

lutein in leafy greens, and the thou-

sands of phytochemicals in broc-

coli, kale, and other members of the

cabbage family.

Table 11.5 Major Minerals: Sources, Functions, and Effects of Deficiencies or Excesses*

Mineral common Sources important For chronic Deficiency extreme excess

Calcium Dairy products, dark green

vegetables, dried legumes

Bone, tooth formation;

blood clotting; neural

and muscle action

Stunted growth; increased

risk of osteoporosis

Impaired absorption

of other minerals; kidney

stones

Chloride Table salt, soy sauce,

prepared foods

Formation of gastric fluid;

proper acid–base balance

and nerve cell functioning

Muscle cramps; stunted

growth; poor appetite

May contribute

to hypertension

Chromium Whole grains, meat,

beer, wine

Glucose use in cells Poor control of blood glucose

levels; weight loss

None reported

Copper Nuts, legumes, seafood,

drinking water

Synthesis of melanin, hemoglobin;

electron transport

Anemia; changes in bone

and blood vessels

Nausea; liver damage

Fluorine Fluoridated water,

tea, seafood

Maintaining teeth and bones Tooth decay Digestive upsets;

mottled teeth

Iodine Marine fish, shellfish, iodized

salt, dairy products

Formation of thyroid hormone Enlarged thyroid (goiter);

metabolic disorders

Toxic goiter

Iron Whole grains, leafy greens,

legumes, nuts, eggs, meat,

shellfish, dried fruit

Formation of hemoglobin

and cytochrome used in

electron transport

Iron-deficiency anemia;

impaired immunity

Liver damage; shock;

heart failure

Magnesium Whole grains, legumes, nuts,

dairy products

Coenzyme role in ATP/ADP cycle;

proper muscle, nerve function

Weak, sore muscles;

impaired nerve function

Impaired nerve function

Phosphorus Whole grains, poultry,

red meat

Healthy bones, teeth; forming nucleic

acids, ATP, phospholipids

Muscular weakness; loss of

minerals from bone

Impaired absorption

of minerals into bone

Potassium All whole foods Muscle and neural function; roles

in protein synthesis and acid–base

balance

Muscle weakness Muscle weakness,

paralysis; heart failure

Sodium Table salt , soy sauce,

prepared foods

Healthy salt–water balance; muscle

and nerve cell function

Muscle cramps Hypertension in

susceptible people

Sulfur Dietary proteins Protein synthesis None reported None likely

Zinc Whole grains, legumes, nuts,

meats, seafood

Formation of digestive enzymes;

normal growth, wound healing,

sperm formation, senses of

taste and smell

Stunted growth; scaly skin;

impaired immunity

Nausea; vomiting;

diarrhea; anemia;

impaired immunity

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

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