Minerals are inorganic nutrients. That is, they are materials found in
foods that are essential for growth and health and do not contain the
element carbon. The minerals that are relevant to human
are water, sodium, potassium, chloride, calcium, phosphate, sulfate,
magnesium, iron, copper, zinc, manganese, iodine, selenium, and
molybdenum. Cobalt is a required mineral
for human health, but it is supplied by vitamin B
. There is some evidence that chromium, boron, and other inorganic
elements play some part in human nutrition, but their role has not been
Minerals should be provided by a normal, healthy diet. In special cases,
additional mineral supplements may be called for. Preterm (low birth
weight) infants have special needs for calcium, phosphorus, and sodium, as
well as extra needs for vitamin D. Iron supplements may also be
The amount of each mineral that is needed to support growth during infancy
and childhood, to maintain body weight and health, and to facilitate
, are listed in a table called the Recommended Dietary Allowances (RDA).
This table was compiled by the Food and Nutrition Board, a committee that
serves the United States government. The values listed in the RDA indicate
the daily amounts that are expected to maintain health throughout most of
the general population. The actual levels of each inorganic nutrient
required by any given individual is likely to be less than that stated by
the RDA. The RDAs are all based on studies that provided the exact,
minimal requirement of each mineral needed to maintain health. However,
the RDA values are actually greater than the minimal requirement, as
determined by studies on small groups of healthy human subjects, in order
to accommodate the variability expected among the general population.
Because of differences in individual diets and individual needs, the
decision regarding any child's need for supplements should be made
by the parents after discussion with the pediatrician and, where
appropriate, a nutritionist. Children on a well-balanced diet do not
require supplements, while those who are picky eaters or who routinely eat
a poor diet may benefit from supplementation.
Girls should get their calcium from foods, particularly dairy products,
rather than supplements. Dairy products were associated with higher bone
mineral density in the spine, while calcium supplements had no such
The following discussion describes the role of the major minerals in human
Iron is essential for the formation of hemoglobin, the chemical in the
blood that carries oxygen to the cells. Low levels of iron cause anemia.
In severe cases, the children become flabby, and they fail to grow
normally. Milder cases of iron deficiency may not produce any physical
symptoms, but children may learn at a slower pace than children with a
proper amount of iron in their diet. The combination of rice, beans, and
meat consumed with fresh citrus fruit provides an excellent source of
absorbable iron. Iron supplements are suggested for children who cannot or
will not follow a proper diet through the first two years of life.
Calcium is required for proper development of bones and teeth. It is also
needed for proper muscle activity and blood clotting. Lack of calcium can
cause rickets, a condition in which the bones are soft and develop in
abnormal shapes. Calcium must be accompanied by vitamin D in order to have
the proper effects. Foods rich in calcium include almonds, swiss cheese,
collards, sardines and salmon with bones, spinach, ice cream, kale, beet
greens, cheddar cheese, molasses, oysters, milk, and broccoli.
Zinc deficiency has been associated with reduced growth and
. The best foods for zinc are lamb, beef, leafy grains, root vegetables
such as potatoes and carrots, shellfish, and organ meats such as liver or
kidneys. While a high fiber diet is important for health, too much fiber
can reduce the absorption of zinc and lead to a zinc deficiency.
Iodine is needed in the diet for proper thyroid function. The best source
of iodine is fish, but table salt normally has iodine added to it, and
even modest amounts of salt will meet the daily iodine requirements.
Fluoride is needed for strong teeth. In many areas, drinking water
contains fluoride that meets all normal needs, but for children who do not
drink water or drink filtered or bottled water, fluoride supplements may
be useful. Fluoride supplements may be useful for infants and then may be
discontinued as the child gets older and starts drinking water.
Magnesium is found in so many parts of the body that it is almost
impossible to describe the effects of low magnesium levels. The most
common problems are twitching, and, because of the need for magnesium in
the parathyroid gland, soft bones even when calcium and vitamin D are
adequate. Because magnesium is found in most foods, deficiency is usually
associated with absorption problems and requires medical attention.
Copper is required for blood and nerve fiber development. It is found in
liver, nuts, and seafood.
Phosporus is needed for energy production, metabolism, and healthy bone
development. The best sources
are milk, cheese, meats, whole grains, eggs, peas, and beans.
Potassium is needed for muscle contractions and nerve function. Good
sources of potassium are orange juice, milk, cheese, whole grains, and
Selenium is needed for proper thyroid function. It has also been
associated with prevention of some types of
in adults. Selenium supplements are not normally required except in
receiving a low-protein diet, although it may sometimes be associated
with thyroid problems. In these cases, medical care is required.
Although the greatest nutritional concern is with inadequate levels of
minerals, it is possible to take too much, particularly when people
already eating a normally healthy diet take supplements. The daily intake
of minerals should be reviewed to prevent adverse effects.
Excess calcium may lead to
and kidney problems. Too much zinc may lead to
, and kidney and heart problems. Excess iron may cause problems of the
stomach and digestive tract, liver problems, an increased risk of
diabetes, and male sexual problems.
When minerals are taken properly, they have no side effects.
Minerals can interact with drugs and in excess with each other. Iron and
calcium are known to bind to drugs of the tetracycline family and
inactivate the antibiotic. The compound of calcium and tetracycline may
also be absorbed into a child's teeth, causing discoloration.
Too much calcium in the diet may inhibit absorption of iron, magnesium,
phosphorus, and zinc. Excess iron may reduce the absorption of zinc.
—Pertaining to chemical compounds that are not hydrocarbons or
—A pair of glands adjacent to the thyroid gland that primarily
regulate blood calcium levels.
—A rare, inherited, metabolic disorder in which the enzyme
necessary to break down and use phenylalanine, an amino acid necessary
for normal growth and development, is lacking. As a result,
phenylalanine builds up in the body causing mental retardation and other
—A condition caused by the dietary deficiency of vitamin D,
calcium, and usually phosphorus, seen primarily in infancy and
childhood, and characterized by abnormal bone formation.
Siberry, George K., and Robert Iannone, eds.
The Harriett Lane Handbook
, 15th ed. St. Louis, MO: Mosby, 2000.
Chanoine, J. P. "Selenium and thyroid function in infants,
children, and adolescents."
19 (2003): 137–43.
Matkovic, V., et al. "Nutrition influences skeletal development
from childhood to adulthood: a study of hip, spine, and forearm in
Journal of Nutrition
134 (March 2004): 701S–5S.
American Dietetic Association.
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