Vitamin deficiency is a morbid condition caused by either a complete absence, an inadequate intake and/or production, or an increased destruction of vitamins in the organism. Vital functions require a certain amount of vitamins, some of which are synthesized by intestinal bacteria while others must be ingested. An inadequate diet (including improperly stored or improperly prepared foods) will gradually lead to vitamin deficiency, as will certain diseases which inhibit the natural synthesis of vitamins in the body.
The major vitamins, or vitamin groups, are vitamin A, vitamin B complex, vitamin C, vitamin D, Vitamin E, vitamin F, vitamin H (biotin), vitamin K and vitamin P (bioflavonoids).
Up to half a million children become blind each year because of vitamin A deficiency.