VITAMIN A … FROM PHYSIOLOGY TO DISEASE PREVENTION

Abstract

Vitamin A is an essential micronutrient whose role in visual function has been known for thousands of years. The beneficial effects of vitamin A might have been recognized by the ancient Egyptians who treated eye disease with raw liver. They identified a connection between eye problems and the liver, which is the richest source of vitamin A. The well known basic function of vitamin A is the formation of retinal pigments of the eye. However, today, we know that vitamin A (retinol) and its biologically active derivatives, the retinoids, regulate key processes such as inhibition of cell proliferation, differentiation, apoptosis, shaping the embryo and organogenesis. On the other hand, either vitamin A deficiency or over-intake may be associated with serious health problems. Therefore use of vitamin A must be optimized to obtain the best prophylactic and treatment results. This review will shed the light of different important aspects regarding vitamin A in regulation of physiological body functions, pathological conditions resulting from decreased or chronic excessive administration and its use as an effective tool in prophylaxis and treatment of specific health problems.