bétakarotin

Bétakarotène, also known as beta-carotene, is a carotenoid pigment and provitamin A. It is produced by plants, algae and some fungi, and occurs naturally in many colorful fruits and vegetables. Common dietary sources include carrots, sweet potatoes, pumpkins, leafy greens, apricots, mangoes and various vegetable oils. Commercial beta-carotene used in supplements and as a food colorant is produced by synthetic methods or by microbial or algal fermentation.

Biochemically, beta-carotene has 40 carbon atoms (C40H56) and consists of two beta-ionone rings joined by a long polyene chain. In humans, the enzyme beta-carotene 15,15'-dioxygenase cleaves beta-carotene to form retinal, which can be further converted to retinol (vitamin A). The efficiency of conversion varies among individuals and dietary context. Absorption is fat-dependent, requiring bile and lipids for uptake in the small intestine.

Uses and regulation: Beta-carotene serves as a dietary source of provitamin A and exhibits antioxidant properties in vitro. It is also used as a natural orange food colorant (E160a) and is added to animal feeds to color egg yolks and meat.

Safety: Dietary intake from food is considered safe. High-dose beta-carotene supplements have been associated with an increased risk of lung cancer in smokers in some studies and are not recommended for cancer prevention in that group. Excessive intake can cause carotenodermia (orange coloration of the skin) but is generally harmless. There is no universally established upper limit for beta-carotene from food; supplements should be used with caution.