Ames B N, Shigenaga M K, Hagen T M
Division of Biochemistry and Molecular Biology, University of California, Berkeley 94720.
Proc Natl Acad Sci U S A. 1993 Sep 1;90(17):7915-22. doi: 10.1073/pnas.90.17.7915.
Metabolism, like other aspects of life, involves tradeoffs. Oxidant by-products of normal metabolism cause extensive damage to DNA, protein, and lipid. We argue that this damage (the same as that produced by radiation) is a major contributor to aging and to degenerative diseases of aging such as cancer, cardiovascular disease, immune-system decline, brain dysfunction, and cataracts. Antioxidant defenses against this damage include ascorbate, tocopherol, and carotenoids. Dietary fruits and vegetables are the principal source of ascorbate and carotenoids and are one source of tocopherol. Low dietary intake of fruits and vegetables doubles the risk of most types of cancer as compared to high intake and also markedly increases the risk of heart disease and cataracts. Since only 9% of Americans eat the recommended five servings of fruits and vegetables per day, the opportunity for improving health by improving diet is great.
新陈代谢，如同生命的其他方面一样，涉及权衡取舍。正常新陈代谢产生的氧化副产物会对DNA、蛋白质和脂质造成广泛损害。我们认为这种损害（与辐射产生的损害相同）是衰老以及诸如癌症、心血管疾病、免疫系统衰退、脑功能障碍和白内障等衰老性退行性疾病的主要促成因素。针对这种损害的抗氧化防御包括抗坏血酸、生育酚和类胡萝卜素。膳食中的水果和蔬菜是抗坏血酸和类胡萝卜素的主要来源，也是生育酚的来源之一。与高摄入量相比，低膳食水果和蔬菜摄入量会使大多数类型癌症的风险增加一倍，同时也会显著增加心脏病和白内障的风险。由于只有9%的美国人每天食用推荐的五份水果和蔬菜，通过改善饮食来增进健康的机会很大。
