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Vitamin A

Vitamin A is required for healthy skin and mucus membranes, and for night vision. Its absence from diet leads to a loss in weight and failure of growth in young animals, to the eye diseases; xerophthalmia, and night blindness, and to a general susceptibility to infections. Vitamin A is structurally related to carotene. Carotene is converted into vitamin A in the liver, two molecules of vitamin A are formed from on molecule of beta carotene, hence good sources of carotene, such as green vegetables are good potential sources of vitamin A. Vitamin A is manufactured by extraction from fish-liver oil and by synthesis from beta-ionone.