Ellen Says: β-Carotene is an organic compound and classified as a terpenoid. It is a strongly-coloured red-orange pigment abundant in plants and fruits. β-Carotene is also the substance in carrots that colours them orange. As a carotene with beta-rings at both ends, it is the most common form of carotene.
The structure was deduced by Karrer et al. in 1930. In nature, β-carotene is a precursor (inactive form) to vitamin A via the action of beta-carotene 15,15'-monooxygenase. β-Carotene is biosynthesized from geranylgeranyl pyrophosphate.
Plant carotenoids are the primary dietary source of pro-vitamin A worldwide, with β-carotene as the most well-known pro-vitamin A carotenoid. Others include α-carotene and β-cryptoxanthin. Carotenoids are absorbed into the small intestine by passive diffusion. One molecule of β-carotene can be cleaved by a specific intestinal enzyme into two molecules of vitamin A.