However, this meta-analysis included two large studies of smokers, so it is not clear that the results apply to the general population. The review only studied the influence of synthetic antioxidants and the results should not be translated to potential effects of fruits and vegetables. β-Carotene and photosensitivity
Oral β-carotene is prescribed to people suffering from erythropoietic protoporphyria. It provides them some relief from photosensitivity. Carotenemia
Carotenemia or hypercarotenemia is excess carotene, but unlike excess vitamin A, carotene is non-toxic. Although hypercarotenemia is not particularly dangerous, it can lead to an oranging of the skin (carotenodermia), but not the conjunctiva of eyes (thus easily distinguishing it visually from jaundice). It is most commonly associated with consumption of an abundance of carrots, but it also can be a medical sign of more dangerous conditions. Production
Carotenes are produced in a general manner for other terpenoids and terpenes, i.e. by coupling, cyclization, and oxygenation reactions of isoprene derivatives. Lycopene is the key precursor to carotenoids. It is formed by coupling of geranylgeranyl pyrophosphate and[geranyllinalyl pyrophosphate.Most of the worlds synthetic supply of carotene comes from a manufacturing complex located in Freeport, Texas and owned by DSM. The other major supplier BASF also uses a chemical process to produce β-carotene. Together these suppliers account for about 85% of the β-carotene on the market. In Spain Vitatene produces natural β-carotene from fungus Blakeslea trispora, as does DSM but at much lower amount when compared to its synthetic β-carotene operation.
Specifically, the group of nine carbon atoms at each end form a β-ring. The α-carotene molecule has a β-ring at one end; the other end is called an ε-ring. There is no such thing as an "α-ring". These and similar names for the ends of the carotenoid molecules form the basis of a systematic naming scheme, according to which:

α-carotene is β,ε-carotene;
β-carotene is β,β-carotene;
γ-carotene (with one β ring and one uncyclized end that is labelled psi) is β,ψ-carotene;
δ-carotene (with one ε ring and one uncyclized end) is ε,ψ-carotene;
ε-carotene is ε,ε-carotene
lycopene is ψ,ψ-caroteneζ-Carotene is the biosynthetic precursor of neurosporene, which is the precursor of lycopene, which, in turn, is the precursor of the carotenes α through ε. Food additive
Carotene is used to colour products such as juice, cakes, desserts, butter and margarine. It is approved for use as a food additive in the EU (listed as additive E160a) Australia and New Zealand (listed as 160a) and the US. See also
Antioxidant

References
External links
Carotene at the US National Library of Medicine Medical Subject Headings (MeSH)