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A half-carotene; an intermediate in the vision cycle, it also plays a role in growth and differentiation.
one of the two forms of vitamin A that occur in nature. It is a fat-soluble unsaturated alcohol formed by hydrolysis of beta-carotene, one molecule of which yields two molecules of vitamin A1. Natural sources include fish-liver oils, butterfat, and egg yolk. The vitamin is needed for healthy vision and skin epithelium. Also called retinol.
A form of vitamin A found in fish liver oils.