Dorgan J F, Schatzkin A
Division of Cancer Prevention and Control, National Cancer Institute, Bethesda, Maryland.
Hematol Oncol Clin North Am. 1991 Feb;5(1):43-68.
Antioxidant micronutrients are one of the body's primary defenses against free radicals and reactive oxygen molecules. Carotenoids, vitamin C, and vitamin E trap these molecules, and selenium is an essential component of an antioxidant enzyme. There is considerable support from animal studies for a protective effect of antioxidant micronutrients on cancer. However, the role of these micronutrients in cancer prevention in humans is less clear. Diet studies suggest protective effects of fruits and vegetables on risk of cancer at several sites. Inverse associations between dietary carotenoids and serum beta-carotene and lung cancer have been observed repeatedly. Vitamin C has also been consistently inversely associated with risk of oral and esophageal cancer in diet studies and with stomach cancer in both diet and plasma studies. It remains unknown, however, whether carotenoids and vitamin C or some other component of fruits and vegetables, the primary sources of these micronutrients, prevent cancer in humans. Selenium has been inversely correlated with cancers at numerous sites in ecologic studies, but observational studies do not provide strong support for a protective effect of selenium on cancer at any site. There also is not strong support for a protective effect of vitamin E on cancer in humans. Results of studies on the association of antioxidant micronutrients with cancer at many sites are inconsistent. This could be due to lack of a true protective effect or could be related to methodologic problems in assessing dietary intake in epidemiologic studies.
抗氧化微量营养素是人体对抗自由基和活性氧分子的主要防御手段之一。类胡萝卜素、维生素C和维生素E能捕获这些分子，而硒是一种抗氧化酶的重要组成部分。动物研究为抗氧化微量营养素对癌症的保护作用提供了大量支持。然而，这些微量营养素在人类癌症预防中的作用尚不清楚。饮食研究表明，水果和蔬菜对多个部位的癌症风险具有保护作用。饮食中的类胡萝卜素和血清β-胡萝卜素与肺癌之间的负相关关系已被反复观察到。在饮食研究中，维生素C也一直与口腔癌和食管癌风险呈负相关，在饮食和血浆研究中均与胃癌呈负相关。然而，尚不清楚类胡萝卜素和维生素C或水果和蔬菜（这些微量营养素的主要来源）的其他某些成分是否能预防人类癌症。在生态学研究中，硒与多个部位的癌症呈负相关，但观察性研究并未有力支持硒对任何部位癌症的保护作用。也没有有力证据支持维生素E对人类癌症具有保护作用。关于抗氧化微量营养素与多个部位癌症关联的研究结果并不一致。这可能是由于缺乏真正的保护作用，也可能与流行病学研究中评估饮食摄入量的方法学问题有关。
