What are minerals?
Minerals, in the nutritional sense, are inorganic substances required in theionic or free-element form for life processes. The macrominerals (those needed in the largest amounts) are sodium, potassium, chloride, magnesium, phosphorus, and calcium. The required amounts of all these minerals, except calcium, can easily be satisfied by a normal diet. Deficiencies of calcium can, and frequently do, occur.
Calcium deficiencies can lead to bone
fragility, with concomitant risk of fracture, which is a problem especially for
elderly women. Calcium supplements are indicated in such cases. Requirements
for some microminerals (trace minerals) are not always clear. It is known, for
example, from biochemical evidence that chromium is necessary for glucose
metabolism (a role that has recently been suggested for chromium picolinate)
and that manganese is necessary for bone formation, but no deficiencies of
these elements have been recorded. Requirements have been established for iron,
copper, zinc, iodide, and fluoride; there are DVs for all of these minerals
except fluoride. In the case of copper and zinc, needs are easily met by
dietary sources, and overdoses can be toxic. A deficiency of iodide, leading to
an enlarged thyroid gland, has been a problem in some parts of the United
States for many years. Iodized salt is used to prevent this deficiency, and it
has become unusual to find table salt without an iodine supplement. Fluoride is
administered to prevent tooth decay in children and, with that end in mind, has
been added to water supplies, sometimes causing considerable controversy. Iron
is important because it is part of the structure of the ubiquitous heme
proteins. Women of childbearing age are more susceptible to iron deficiencies
than are other segments of the population, and in some cases supplements are
advised. These recommended levels vary with the age of the individual and are
subject to adjustment for level of activity.