Vitamin A is essential for normal vision, for maintaining the integrity of epithelial tissues and for a wide variety of metabolic functions. One of the earliest manifestations of vitamin A deficiency is night blindness and more severe deficiencies include ocular changes leading to blindness, particularly in young children. Very low intakes, poor bio-availability of pro-vitamin A from the predominantly vegetarian diet and recurrent infections are thought to be the main reasons for widespread prevalence of vitamin A deficiency.