自由基、抗氧化剂、营养素与健康的关系

超氧化物歧化酶 (SOD)清除 O2·作用的新发现揭开需氧生物体内产生氧自由基的奥秘 ,从而诞生并发展了自由基生物学。一氧化氮 (NO)的生理学作用与病理生理学作用的首次发现和随后的研究进展不仅充实了这门崭新学科的内容 ,而且使其发展更为迅速、蓬勃。该学科的研究范围已扩展到其它生物学科 ,包括营养学 1 ,2 ] ,如抗氧化剂已成为“热点”研究领域。对于自由基、抗氧化剂与营养 ,我们业已论述3 ] 。在此基础上 ,现进一步提出自由基、抗氧化剂、营养素与健康的关系的初步见解。1　需氧生物体内自由基、抗氧化剂、营养物质与生命的关系…

FREE RADICALS, ANTIOXIDANTS, AND NUTRIENTS IN RELATION TO HEALTH

The homeostasis of free radicals is vital to the evolution and life of oxygen-requiring organisms. Under normal physiological conditions, rates of the production of free radicals are virtually equal to rates of their removal. The cytotoxic effect of free radicals is deleterious to cells and mediates the pathogenesis of a wide array of diseases. Therefore, antioxidants (e.g. vitamin C, vitamin E, β-carotene, and glutathione) are essential to the survival, health, and reproduction of animals, including humans. Antioxidants may be classified as nutritionally essential (e.g. vitamin antioxidants), indirectly essential (e.g., dietary fibre), conditionally essential (e.g. flavonoids and other effective phytochemicals) or non-essential. In the body, appropriate nutrition should not only prevent diseases, but also promote free radical homeostasis. Thus, it is crucial to develop useful indicators of oxidative stress, such as the cellular ratio of /, lipid peroxidation, oxidative modification of protein and DNA damage. On the basis of the recent report that the improper therapy of iron deficiency results in free radical-mediated dysfunction of the gastrointestinal tract, it is important to verify whether the formulated requirement of nutrients meet the need of maintaining the homeostasis of free radicals. The recommended intake of vitamin E, vitamin C and other antioxidants may need to be revised so as to protect the body against oxidative stress brought about by endogenous and exogenous factors. In order to delay aging and promote health in humans of all ages, and eliminate oxidative damage in response to the treatment of certain diseases, special nutritional measures should be taken. These measures may include the control of caloric intake, reduction in the absorption of free radicals and electrophilic substances, and adequate provision of antioxidant nutrients as well as effective phytochemicals and nutraceuticals. We predict that the concept of free radical biology will continue to greatly advance life sciences, including nutrition and medicine. The 21st century holts great promise for both discoveries and applications in this rapidly emerging field of"antioxidants and health".