Vitamins became known because of the vitamin-deficiency diseases, such as pellagra, beriberi, rickets, and scurvy. The discovery, identification, and synthesis of the vitamins has essentially eliminated these diseases in the United States. Actually, in this country today, instead of simple vitamin replacement, megavitamin therapy is currently being touted as the cure or prevention of various disorders, including the common cold.1
The ordinary diet of most people contains enough vitamins to satisfy daily requirements. However, several conditions increase the demand for vitamins above that provided in a normal diet.2 For example, alcoholism, chronic infections, malignancy, and chronic hemolysis require additional folic acid. On the other hand, a dietary deficiency of B12 is almost impossible to achieve except in vegetarians, and dietary thiamine deficiency is extremely rare except in alcoholics.
Vitamins are separated into two groups according to their absorptive medium. Vitamins A, D, E, and K are fat