upper limits set, the amounts of nutrients in supple-
ments are not regulated by the Food and Drug Admin-
istration (FDA). Therefore, supplement users must be
aware of the potential adverse effects and choose sup-
plements with moderate amounts of nutrients.Major Minerals
The major minerals present in the body include
sodium, potassium, chloride, calcium, magnesium,
phosphorus, and sulfur.
Functions. The fluid balance in the body, vital for
all life processes, is maintained largely by sodium,
potassium, and chloride. Fluid balance is regulated
by charged sodium and chloride ions in the extracel-
lular fluid (outside the cell) and potassium in the intra-
cellular fluid (inside the cell), and by some other
electrolytesacross cell membranes. Tight control is
critical for normal muscle contraction, nerve impulse
transmission, heart function, and blood pressure.
Sodium plays an important role in the absorption of
other nutrients, such as glucose, amino acids, and
water. Chloride is a component of hydrochloric acid,
an important part of gastric juice (an acidic liquid
secreted by glands in the stomach lining) and aids in
food digestion. Potassium and sodium act as cofactors
for certain enzymes.
Calcium, magnesium, and phosphorus are known
for their structural roles, as they are essential for the
development and maintenance of bones and teeth.
They are also needed for maintaining cell membranes
and connective tissue. Several enzymes, hormones,
and proteins that regulate energy and fat metabolism
require calcium, magnesium and/or phosphorus tobecome active. Calcium also aids in blood clotting.
Sulfur is a key component of various proteins and
vitamins and participates in drug-detoxifying path-
ways in the body.
Disease prevention and treatment. Sodium, chlor-
ide, and potassium are linked to high blood pressure
(hypertension) due to their role in the body’s fluid
balance. High salt or sodium chloride intake has been
linked to cardiovascular disease as well. High potas-
sium intakes, on the other hand, have been associated
with a lower risk of stroke, particularly in people with
hypertension. Research also suggests a preventive role
for magnesium in hypertension and cardiovascular dis-
ease, as well as a beneficial effect in the treatment of
diabetes,osteoporosis, and migraine headaches.
Osteoporosis is a bone disorder in which bone
strength is compromised, leading to an increased risk
of fracture. Along with other lifestyle factors, intake of
calcium and vitamin D plays an important role in the
maintenance of bone health and the prevention and
treatment of osteoporosis. Good calcium nutrition,
along with low salt and high potassium intake, has
been linked to prevention of hypertension and kidney
stones.
Deficiency. Dietary deficiency is unlikely for most
major minerals, except in starving people or those with
protein-energy malnutrition in developing countries,
or people on poor diets for an extended period, such as
those suffering from alcoholism, anorexia, or bulimia.
Most people in the world consume a lot of salt, and it is
recommended that they moderate their intake to pre-
vent chronic diseases (high salt intake has been asso-
ciated with an increased risk of death from stroke and
cardiovascular disease). However, certain conditions,
such as severe or prolonged vomiting or diarrhea, the
use ofdiuretics, and some forms of kidney disease,
lead to an increased loss of minerals, particularly
sodium, chloride, potassium, and magnesium. Cal-
cium intakes tend to be lower in women and vegans
who do not consume dairy products. Elderly people
with suboptimal diets are also at risk of mineral defi-
ciencies because of decreased absorption and
increased excretion of minerals in the urine.
Toxicity. Toxicity from excessive dietary intake of
major minerals rarely occurs in healthy individuals.
Kidneys that are functioning normally can regulate
mineral concentrations in the body by excreting the
excess amounts in urine. Toxicity symptoms from
excess intakes are more likely to appear with acute or
chronic kidney failure.
Sodium and chloride toxicity can develop due to
low intake or excess loss of water. Accumulation ofKEY TERMS
Absorption—Uptake by the digestive tract.
Bioavailability—Availability to living organisms,
based on chemical form.
Caries—Cavities in the teeth.
Cretinism—Arrested mental and physical develop-
ment.
Fortified—Altered by addition of vitamins or
minerals.
Myoglobin—Oxygen storage protein in muscle.
Neurotransmitter—Molecule released by one
nerve cell to stimulate or inhibit another.
Phytate—Plant compound that binds minerals,
reducing their ability to be absorbed.Minerals