Eichholzer M, Lüthy J, Gutzwiller F, Stähelin H B
Institute for Social and Preventive Medicine, University of Zurich, Switzerland.
Int J Vitam Nutr Res. 2001 Jan;71(1):5-17. doi: 10.1024/0300-9831.71.1.5.
Evidence that fruit and vegetables may protect against coronary heart disease is accumulating. It is unclear which constituents of fruit and vegetables are responsible for this protective effect. Folate as a co-substrate in homocysteine metabolism may be important. An intake of about 400 micrograms folate equivalents/day seems to be required to achieve stable low homocysteine blood levels. Five of eight epidemiologic studies show significant inverse associations between folate and cardiovascular disease. These associations could be confounded by antioxidant vitamins and/or other substances. In trials examining an association between folate and cardiovascular disease such confounding must be excluded, before specific recommendations can be given. Observational studies suggest that vitamin C plays a role in the aetiology of cardiovascular disease, but there are no completed intervention trials of this vitamin alone. With regard to vitamin E two cohort studies point to cardiovascular benefits with the long-term use of supplements of at least 100 IU/day, but the results of controlled trials are inconclusive. There is some evidence from observational studies of an inverse association between beta-carotene and cardiovascular disease, particularly in smokers. Intervention trials do not support this hypothesis, rather, they suggest a possible harmful effect of beta-carotene supplements in smokers. Nevertheless, protective effects of beta-carotene and vitamin E in different dosages, durations of administration, or different combinations are still possible. The last paragraph of this review discusses limitations of the present and priorities of future research.
越来越多的证据表明，水果和蔬菜可能有助于预防冠心病。目前尚不清楚水果和蔬菜中的哪些成分具有这种保护作用。叶酸作为同型半胱氨酸代谢中的一种辅助底物可能很重要。为使同型半胱氨酸血液水平稳定降低，似乎每天需要摄入约400微克叶酸当量。八项流行病学研究中有五项表明叶酸与心血管疾病之间存在显著的负相关。这些关联可能会被抗氧化维生素和/或其他物质混淆。在研究叶酸与心血管疾病之间关联的试验中，在给出具体建议之前，必须排除这种混淆因素。观察性研究表明，维生素C在心血管疾病的病因学中起作用，但尚无单独针对该维生素的完整干预试验。关于维生素E，两项队列研究指出，长期每天服用至少100国际单位的补充剂对心血管有益，但对照试验的结果尚无定论。观察性研究有一些证据表明，β-胡萝卜素与心血管疾病之间存在负相关，尤其是在吸烟者中。干预试验不支持这一假设，相反，它们表明β-胡萝卜素补充剂对吸烟者可能有有害影响。尽管如此，不同剂量、给药持续时间或不同组合的β-胡萝卜素和维生素E仍可能具有保护作用。本综述的最后一段讨论了当前的局限性和未来研究的重点。
