Search results
Results From The WOW.Com Content Network
This is a list of antioxidants naturally occurring in food. Vitamin C and vitamin E – which are ubiquitous among raw plant foods – are confirmed as dietary antioxidants, whereas vitamin A becomes an antioxidant following metabolism of provitamin A beta-carotene and cryptoxanthin.
β-Carotene (beta-carotene) is an organic, strongly colored red-orange pigment abundant in fungi, [7] plants, and fruits. It is a member of the carotenes , which are terpenoids (isoprenoids), synthesized biochemically from eight isoprene units and thus having 40 carbons .
α-Carotene is produced when the all-trans lycopene first undergoes reaction with epsilon-LCY then a second reaction with beta-LCY; whereas β-carotene is produced by two reactions with beta-LCY. α- and β-Carotene are the most common carotenoids in the plant photosystems but they can still be further converted into xanthophylls by using beta ...
Canthaxanthin biosynthesis proceeds from beta-carotene via the action of a single protein, known as a beta-carotene ketolase, that is able to add a carbonyl group to carbon 4 and 4' of the beta carotene molecule. Although functionally identical, several distinct beta-carotene ketolase proteins are known.
High doses of some antioxidants may have harmful long-term effects. The Beta-Carotene and Retinol Efficacy Trial (CARET) study of lung cancer patients found that smokers given supplements containing beta-carotene and vitamin A had increased rates of lung cancer. [141] Subsequent studies confirmed these adverse effects. [142]
Vitamin A occurs as two principal forms in foods: A) retinoids, found in animal-sourced foods, either as retinol or bound to a fatty acid to become a retinyl ester, and B) the carotenoids α-carotene (alpha-carotene), β-carotene, γ-carotene (gamma-carotene), and the xanthophyll beta-cryptoxanthin (all of which contain β-ionone rings) that ...
Astaxanthin / æ s t ə ˈ z æ n θ ɪ n / is a keto-carotenoid within a group of chemical compounds known as carotenones or terpenes. [3] [4] [5] Astaxanthin is a metabolite of zeaxanthin and canthaxanthin, containing both hydroxyl and ketone functional groups.
High-dose supplements of antioxidants may be linked to health risks in some cases, including higher mortality rates. For example, high doses of beta-carotene and vitamin E was found to increase the risk of lung cancer and overall mortality in smokers. [2] High doses of vitamin E may increase risks of prostate cancer and one type of stroke.