van Poppel G, Goldbohm R A
TNO Nutrition and Food Research Institute, Department of Epidemiology, Zeist, Netherlands.
Am J Clin Nutr. 1995 Dec;62(6 Suppl):1393S-1402S. doi: 10.1093/ajcn/62.6.1393S.
In 1981 it was hypothesized that a high dietary intake of beta-carotene might reduce human cancer rates. Since then, several observational epidemiologic studies have addressed this topic. The results of both case-control and cohort studies show a remarkable consistency for the association of increased lung cancer risk with low amounts of dietary beta-carotene or low plasma beta-carotene concentrations. For stomach cancer, the evidence is also consistent, although the number of studies is more modest. For breast and prostate cancer, the studies indicate no consistent association of plasma or dietary beta-carotene and reduced cancer risk. For colorectal cancer, the effect will be moderate, if existent. For several other cancer sites, the numbers of cases in prospective studies are often small, implying that only strong associations can be detected. For some of these sites, results from retrospective studies are promising. The epidemiologic studies should be carefully interpreted because dietary habits may be misclassified and smoking may reduce plasma beta-carotene concentrations. Observational epidemiology cannot definitively resolve whether associations are indeed due to beta-carotene, or to other components of fruit and vegetables that are rich in beta-carotene. However, overall results are promising and several plausible cancer preventive mechanisms have been reported for beta-carotene. The ongoing human intervention studies will provide more answers regarding cancer prevention by beta-carotene but may need long follow-ups to be conclusive.
1981年有人提出，高膳食摄入β-胡萝卜素可能会降低人类患癌率。从那时起，几项观察性流行病学研究探讨了这一主题。病例对照研究和队列研究的结果均显示，肺癌风险增加与膳食中β-胡萝卜素含量低或血浆β-胡萝卜素浓度低之间的关联具有显著一致性。对于胃癌，尽管研究数量较少，但证据也较为一致。对于乳腺癌和前列腺癌，研究表明血浆或膳食中的β-胡萝卜素与降低癌症风险之间没有一致的关联。对于结直肠癌，如果存在影响，其作用将是中等程度的。对于其他几个癌症部位，前瞻性研究中的病例数往往较少，这意味着只能检测到强关联。对于其中一些部位，回顾性研究的结果很有前景。流行病学研究的结果应谨慎解读，因为饮食习惯可能被错误分类，吸烟可能会降低血浆β-胡萝卜素浓度。观察性流行病学无法明确确定这些关联是否确实归因于β-胡萝卜素，还是归因于富含β-胡萝卜素的水果和蔬菜的其他成分。然而，总体结果很有前景，并且已经报道了几种关于β-胡萝卜素的合理的癌症预防机制。正在进行的人体干预研究将提供更多关于β-胡萝卜素预防癌症的答案，但可能需要长期随访才能得出结论。
