Avitaminosis

Overview
Avitaminosis is any disease caused by chronic or long-term vitamin deficiency or caused by a defect in metabolic conversion, such as tryptophan to niacin. They are designated by the same letter as the vitamin. Avitaminoses include
 * vitamin A deficiency causes xerophthalmia or night blindness
 * thiamine deficiency causes beriberi
 * niacin deficiency causes pellagra
 * vitamin B12 deficiency leads to megaloblastic anemia
 * vitamin C deficiency leads to scurvy
 * vitamin D deficiency causes rickets
 * vitamin K deficiency causes bleeding

Conversely hypervitaminosis is the syndrome of symptoms caused by over-retention of fat-soluble vitamins in the body.