(written as vitamin A)A long-chain fat-soluble alcohol which exist in various forms of which the most active is retinol which is found in animal tissues. Precursors of the vitamin are widely distributed in vegetables as carotenes which are transformed in the intestinal wall into Vitamin A. It is concerned with the integrity of epithelial tissues (skin and mucous membranes) and of the retina, especially for low light conditions, and is also needed for the correct functioning of many body cells. Major food sources are fish and animal livers, eggs and milk. It is possible to overdose.
- noun a vitamin which is soluble in fat and can be formed in the body from precursors but is mainly found in food such as liver, vegetables, eggs and cod liver oil.