Candlish J K, Das N P
Biochemistry Department, National University of Singapore, Singapore.
Biomed Environ Sci. 1996 Sep;9(2-3):117-23.
Both preventive and chain breaking antioxidants have a role in the limitation of free radical damage. Some of these may be regarded as "classical", like vitamins E and C but others are more recently discovered, such as the flavonoids, widespread in plant tissues, and the muscle constituents anserine and carnosine. The major conditions in which the role of antioxidants is under intense investigation include coronary artery disease, cancer and diabetes. There are theoretical underpinnings for the efficacy of antioxidants in each of these, with the protection of low density lipoprotein (in respect of the first) being exceptionally persuasive. Much attention is now being focussed on the flavonoids, which are surprisingly pleiotropic in their effects. For one of them, quercetin, over a dozen seemingly independent biological effects can be listed, including the inhibition of low density lipoprotein oxidation. Flavonoids also inhibit peroxidation in foodstuffs, as opposed to tissues. There is much controversy over antioxidant supplementation policies, some authorities recommending a massive programme of supplementation for all ages and classes, others stressing the value of the traditional mixed diet. This matter is unlikely to be resolved soon, but in the meantime sensible supplementation policies should be continued for those most vulnerable, that is, babies and the aged.
预防性抗氧化剂和链断裂抗氧化剂在限制自由基损伤方面都发挥着作用。其中一些可被视为“经典”抗氧化剂，如维生素E和维生素C，但其他一些则是最近才发现的，例如广泛存在于植物组织中的类黄酮，以及肌肉成分鹅肌肽和肌肽。目前正在深入研究抗氧化剂作用的主要疾病包括冠状动脉疾病、癌症和糖尿病。在这些疾病中，抗氧化剂发挥作用都有理论依据，其中抗氧化剂对低密度脂蛋白的保护作用（针对第一种疾病）尤其有说服力。现在人们的注意力大多集中在类黄酮上，其作用多得惊人。以其中一种槲皮素为例，可以列出十几种看似独立的生物学效应，包括抑制低密度脂蛋白氧化。与在组织中不同，类黄酮还能抑制食品中的过氧化反应。关于抗氧化剂补充政策存在很多争议，一些权威机构建议为所有年龄和阶层开展大规模补充计划，另一些则强调传统混合饮食的价值。这个问题不太可能很快得到解决，但与此同时，应该继续为最脆弱人群，即婴儿和老年人，制定合理的补充政策。
