The Health Benefits of Carotenoids
Carotenoids play an important role in human health by acting as biological antioxidants, protecting cells and tissues from the damaging effects of free radicals and singlet oxygen. Their role as antioxidants are based on an extensive system of conjugated double bonds which, upon reacting with singlet oxygen for example, absorb and diffuse the oxygen’s potentially destructive energy. The singlet oxygen returns to its lower energy ground state, and dissipates the absorbed energy harmlessly as heat. Similar mechanisms are involved in quenching the oxidative potential of hydroxyl radicals and other free radical compounds.(Handelman GJ. Carotenoids as scavengers of active oxygen species. In Cadenas E, Packer L (eds). Handbook of Antioxidants. New York : Marcel Dekker, Inc. 1996. p259-314)
The most widely studied and well-understood nutritional role for carotenoids is their pro-vitamin A activity. Vitamin A deficiency among children in developing countries remains the leading cause of preventable visual impairment and blindness, and is a significant contributor to severe infections and death, particularly those caused by diarrhea and measles. It has been estimated that 500,000 preschool-age children, world-wide, become blind each year as a result of vitamin A deficiency. Millions of others probably suffer from night blindness, a common clinical sign of inadequate vitamin A intake. Further estimates suggest that more than 100 million children suffer from vitamin A inadequacy without showing clinical signs of acute deficiency.
Vitamin A deficiency is also likely to increase vulnerability to other illnesses in both women and children, such as iron-deficiency or anemia, and may be an important factor contributing to poor maternal performance during pregnancy and lactation and to growth deficits in children.
Vitamin A is further involved in the activation of gene expression and, subsequently, the control of cell differentiation in the development of various tissues and organs in the body. It is through this function that vitamin A affects immune function, taste, hearing, appetite, skin renewal, bone development, and growth. (olson ja. Vitamin a. In ziegler ee, filter lj. Present knowledge in nutrition. Washinton (dc):ilsi press. 1996 p 109-19).
Other health benefits of carotenoids include enhancement of immune system function (bendich, a 1989 carotenoids and the immune response. J. Nutr., 119:112-115), protection from sunburn (matthews-roth, mm 1990 plasma concentration of carotenoids after large doses of beta-carotene. Am.j. Clin. Nutr., sep 52:3, 500-1), and inhibition in development of certain types of cancers (nishino, h. 1998 cancer prevention by carotenoids. Mutat. Res.,402:159-163).
The protective effects of carotenoids against serious disorders such as cancer, heart disease and degenerative eye disease have been recognized, and have stimulated intensive research into the role of carotenoids in human health.