Vitamin A, a lipid-soluble vitamin, is formed by cleavage of certain carotenoids, and is therefore obtained as pro-vitamin A from a range of green and orange fruits and vegetables. It is important as a chromophore in the retina, and also acts as a regulator of transcription of genes encoding proteins involved in embryogenesis, differentiation, reproduction, hematopoiesis and the immune response. Vitamin A deficiency affects over 100 million children in the developing world. Vitamin A is used in the treatment of acute promyelocytic leukemia and severe acne. A high intake of vitamin A from supplements has in some, but not all studies been associated with an increase in the risk of osteoporosis.

Learning goals:

• Absorption, transportation, metabolism, storage and degradation of vitamin A.
• Regulation of gene expression by vitamin A.
• Vitamin A and acute promyelocytic leukemia.
• Role of vitamin A in the visual process.
• Effects of deficiency; practical measures to correct deficiency.
• Vitamin A and immunity.
• Vitamin A toxicity.
• Sources of vitamin A in the diet; recommended intake.
• Vitamin A and osteoporosis.

Prevalence of vitamin A deficiency, from WHO data 2007

Literature:

• Shils et al., Modern Nutrition in Health and Disease
• Garrow et al., Human Nutrition and Dietetics
• Mat og Medisin
• Nordiska Näringsrekommendationer
• Dietary Reference Intakes (DRI)