Excessive intake of beta-carotene leads to yellowish skin, but this is quickly reversible upon cessation of intake. However, this conversion factor does not take into account the poor bioavailability of carotenoids in humans. A activity from beta-carotene Stability Carotenoids can loose some of their activity in foods during storage, due to the action of enzymes and exposure to light and oxygen. Dehydration of vegetables and fruits may greatly reduce the biological activity of carotenoids. Singlet oxygen quenching Beta-carotene can quench singlet oxygen, a reactive molecule that is generated, for instance in the skin by exposure to ultraviolet light and which can induce precancerous changes in cells.
Singlet oxygen has the ability to trigger the generation of free radical chain reactions.
Free radicals can damage lipids in cell membranes as well as the genetic material in cells, and the resulting damage may lead to the development of cancer. 6f retinol or 4.8 mg of beta-carotene. Apart from its provitamin A function, data continue to accumulate supporting a role for beta-carotene as an important micronutrient in its own right. Supplements beta-Carotene is available in hard and soft gelatin capsules, in multivitamin tablets, and in antioxidant vitamin formulas. In a number of animal and human studies beta-carotene supplementation was found to enhance certain immune responses.