Chapter 4 - Vitamin deficiency

Abstract

Freedom from clinical diseases caused by insufficient vitamin nutriture has generally been used as the main criterion by which vitamin requirements have been defined. The term “vitamin deficiency,” therefore, simply refers to the condition of hypovitaminosis, which can be caused by inadequate supply, malabsorption, or impaired metabolism of the vitamin. Hypovitaminosis underlies the various biochemical changes, physiological and/or functional impairments, or other overt disease signs by which the need for a vitamin is defined. The clinical signs of a vitamin deficiency are actually the end result of a chain of events that starts with the diminution in cells and tissues of the metabolically active form of the vitamin and progresses through metabolic perturbations that lead to cellular and, ultimately, organ dysfunction.