Lee I M
Division of Preventive Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, 02215, USA.
Proc Assoc Am Physicians. 1999 Jan-Feb;111(1):10-5. doi: 10.1046/j.1525-1381.1999.09230.x.
Cancer is a leading cause of morbidity and mortality in the United States and other developed countries. In searching for preventive strategies against this disease, researchers have postulated that antioxidant vitamins may play a role in preventing cancer since several plausible biological mechanisms exist. This article reviews the epidemiological evidence for a role of antioxidant vitamins (in particular, beta-carotene, vitamin E, and vitamin C) in the development of cancer. Observational studies provide fairly consistent data for an inverse association between high intake of antioxidant vitamins, especially beta-carotene and vitamin C, and cancer risk. However, randomized trials generally have not supported the hypothesis. Several explanations for these inconsistent findings are possible. These include: 1) confounding by other healthy dietary and nondietary habits in observational studies; 2) the protective role of a combination of many different nutrients present in fruits and vegetables, rather than the single nutrient or combination of two nutrients that most trials have tested; 3) inadequate duration of follow-up in most randomized trials; and 4) heterogeneity of the populations studied. Reliable epidemiological evidence regarding whether antioxidant vitamins play a role in preventing cancer will have to come from both observational studies and randomized trials since these different study designs each have unique strengths and limitations. Based on the available evidence, it seems prudent to advocate a diet rich in fruits and vegetables, rather than the consumption of specific antioxidant vitamin supplements, in order to decrease the risk of developing cancer.
癌症是美国和其他发达国家发病和死亡的主要原因。在寻找针对这种疾病的预防策略时，研究人员推测抗氧化维生素可能在预防癌症中发挥作用，因为存在几种合理的生物学机制。本文综述了抗氧化维生素（特别是β-胡萝卜素、维生素E和维生素C）在癌症发生中作用的流行病学证据。观察性研究提供了相当一致的数据，表明高摄入抗氧化维生素，尤其是β-胡萝卜素和维生素C，与癌症风险呈负相关。然而，随机试验通常不支持这一假设。对于这些不一致的发现有几种可能的解释。这些包括：1）观察性研究中其他健康饮食和非饮食习惯的混杂因素；2）水果和蔬菜中存在的多种不同营养素组合的保护作用，而不是大多数试验所测试的单一营养素或两种营养素的组合；3）大多数随机试验的随访时间不足；4）所研究人群的异质性。关于抗氧化维生素是否在预防癌症中发挥作用的可靠流行病学证据将必须来自观察性研究和随机试验，因为这些不同的研究设计各有其独特的优势和局限性。根据现有证据，提倡食用富含水果和蔬菜的饮食，而不是食用特定的抗氧化维生素补充剂，以降低患癌风险，似乎是谨慎的做法。
