carotene (kârˈətēnˌ) [key], long-chained, unsaturated hydrocarbon found as a pigment in many higher plants, particularly carrots, sweet potatoes, and leafy vegetables. Carotene is thought to assist in trapping light energy for photosynthesis or to aid in chemical reduction. It is important in animal biology as the main dietary source of vitamin A (see vitamin), which is produced by splitting one molecule of carotene into two molecules of vitamin A. Carotene that is thus converted is called provitamin A. This reaction occurs in either the liver or intestinal wall. The absorption of dietary carotene is dependent on the action of bile. Its absorption is less efficient than that of vitamin A. High intake of dietary carotene is being studied for its disease prevention potential. Carotenes are the simplest of a group of natural pigments called carotenoids, of which there are more than 600.