VITAMINS AND MINERALS
a. Biochemical Importance. Vitamins have great biochemical importance
because they are essential for maintenance of normal metabolic function, growth, and
health. The name vitamin means "vital for life." Only a few vitamins are synthesized in
the body. Thus, most vitamins must be ingested in food or in their pure form as dietary
supplements. Only small amounts of vitamins are necessary for growth and health, and
an adequate and varied diet will provide all the vitamins needed, except during
pregnancy and infancy. Restricted diets as a result of cultural or idiosyncratic beliefs,
alcoholism, poverty, ignorance, or disorders of the GI tract that interfere with absorption
will lead to vitamin deficiency. In these cases, vitamin preparations are therapeutic.
b. Oral Sources. Oral sources of minerals may be found commercially,
individually, or combined within a multivitamin and mineral combination. These
minerals are inorganic constituents of foods and biological fluids and play a specific role
as nutrients. The absence from the diet of only a few of these minerals has been shown
to produce specific deficiency problems. A few are known to be involved in metabolic
functions and are therefore possible dietary essentials.
c. Vitamins. Vitamins fall into two categories, lipid (fat) soluble or water-
soluble. The lipid soluble vitamins are A, D, E, and K. Vitamins C and B complex are
examples of water-soluble vitamins.
d. Problems Associated with Excessive Vitamin Intake. Most problems
associated with excessive vitamin intake are related to fat-soluble vitamins because of
retention in the body. Problems with excessive water-soluble vitamin intake are minimal
because they are rapidly excreted in the urine.
a. Fat-Soluble Vitamins. Fat-soluble vitamins are well absorbed from the
normal GI tract. Bile is essential for absorption; therefore, biliary obstruction or hepatic
disease may cause impairment of absorption.
b. Fatty Deposits of Fat-Soluble Vitamins. In general, fat-soluble vitamins will
be stored in fatty deposits throughout the body. They may be excreted in the urine as
water-soluble metabolites or in the feces, by biliary excretion.