carotene The red and orange pigments of many plants, obvious in carrots, red palm oil, and yellow maize, but masked by chlorophyll in leaves. Three main types of carotene in foods are important as precursors of vitamin A: α‐, β‐ and γ‐carotene, which are also used as food colours. Plant foods contain a considerable number of other carotenes, most of which are not precursors of vitamin A.

Carotene is mostly converted into vitamin A (retinol) in the wall of the intestine, but some is absorbed unchanged. 6 μg of β‐carotene, and 12 μg of other provitamin A carotenoids, are nutritionally equivalent to 1 μg of preformed vitamin A. About 30% of the vitamin A in Western diets, and considerably more in diets in less‐developed countries, comes from carotene.

In addition to their role as precursors of vitamin A, carotenes are antioxidant nutrients, and there is evidence that they provide protection against ischaemic heart disease and some forms of cancer. There is no evidence on which to base reference intakes of carotene other than as a precursor of vitamin A.

car·o·tene / ˈkarəˌtēn/ • n. Chem. an orange or red plant pigment found in carrots and many other plant structures. It is a terpenoid hydrocarbon with several isomers, of which one (beta carotene) is important in the diet as a precursor of vitamin A.

carotene A member of a class of carotenoid pigments. Examples are β-carotene and lycopene, which colour carrot roots and ripe tomato fruits respectively. α- and β-carotene yield vitamin A when they are broken down during animal digestion; β-carotene has antioxidant properties.

carotene (ka-rŏ-teen) n. a yellow, orange, red, or brown plant pigment; one of the carotenoids. The most important form, β-carotene, is an antioxidant and can be converted in the body to retinol (vitamin A).

carotene One of a group of hydrocarbon carotenoids.