|
Macrominerals:
Six macrominerals are
required by humans in amounts varying from 0.3 to 2.0 g/day:
1. Four cations:
-
Sodium
-
Potassium
-
Calcium
-
Magnesium
2. Two anions:
Microminerals:
Nine trace minerals - microminerals -
are required by humans in small amounts (micrograms to milligrams per
day):
-
iron
-
iodine
-
fluorine
-
zinc
-
Chromium
-
Selenium
-
Manganese
-
Molybdenum
-
Copper.
Except for fluorine and chromium, each of
these minerals is a component of an enzyme or endocrine system. All trace
minerals are toxic at high levels, and some (arsenic, nickel, and
chromium) have been implicated in carcinogenesis.
Except for deficiencies of
iron, zinc and iodine, mineral deficiencies do not often develop
spontaneously in adults on ordinary diets; however, infants are more
vulnerable because of their rapid growth and variation in intake.
The use
of synthetic diets for the treatment of inborn errors of metabolism and
the development of parenteral nutrition and renal dialysis, all of which
present iatrogenic risks, demonstrate the nutritional importance of trace
minerals.
Toxicity can result from the excess intake of trace
minerals - for example, in "health foods" touted as a source of
protection against chronic diseases. Sometimes mineral deficiency or
toxicity is caused by hereditary diseases.
Source: Merck
|