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建议 抗氧化剂真能抗癌吗
铺天盖地的营养品广告告诉我们要多补充抗氧化剂和维生素，可以抗衰老、预防癌症。然而美国科学家公布的一项研究结果显示，抗氧化剂和维生素似乎并不能增强人体预防肺癌的能力，这一结果可能会让许多吸烟者大失所望。
Contrary to what some smokers may hope, antioxidants and other vitamins seem to offer no protection against lung cancer, new research suggests.
In an analysis of eight previous studies, researchers found no evidence that vitamins A, C, E or folate lower a person’s risk of lung cancer.
Across the studies, which followed thousands of adults for up to16 years, people with the highest intakes of the vitamins were no less likely to develop lung cancer than those with the lowest intakes.
There has been a popular notion that even smokers can ward off lung cancer by taking vitamin supplements, Dr. Eunyoung Cho, the lead author of the new report, told Reuters Health.
This is not true, and our study confirmed that, said Cho, an assistant professor of medicine at Harvard Medical Schooland Brigham and Women Hospital in Boston.
She and her colleagues report the findings in the International Journal of Cancer.
Vitamins C and E are antioxidants, which means they help neutralize cell-damaging substances in the body called free radicals. Vitamin A and folate, a B vitamin, also help maintain normal, healthy cells.
All of these vitamins have been hypothesized to cut lung cancer risk, according to Cho’s team, but the research evidence has been spotty. In particular, most prospective studies – those that follow people over time -- have found no clear protective effect.
But because these studies have included only a small number of lung cancer cases, their findings are less reliable. So Cho and her colleagues pooled data from eight prospective studies that followed a total of 430,281 adults in Europe and North America, including3,206 who developed lung cancer.
After the researchers factored in smoking habits and other variables, like overall diet, weight and education, there was no evidence that vitamins A, C, E or folate reduced lung cancer risk.
There was initially some evidence that vitamin C from food, but not supplements, was protective. But that connection disappeared when the researchers accounted for beta-cryptoxanthin, a plant chemical that gives color to oranges, red peppers, carrots and other red-orange fruits and vegetables.
Because many vitamin C-rich foods contain beta-cryptoxanthin, the latter nutrient may help explain the link some studies have found between vitamin C and lower lung cancer risk, the researchers speculate.
In fact, it is still possible that nutrient-rich fruits and vegetables, if not individual vitamins, help protect against lung cancer, Cho said.
These foods, she explained, might confer benefits through components other than vitamins, or through their unique combinations of nutrients -- though, she added, there is still much to be learned in this area.
抗氧化剂真能抗癌吗
抗氧化剂真能抗癌吗
铺天盖地的营养品广告告诉我们要多补充抗氧化剂和维生素，可以抗衰老、预防癌症。然而美国科学家公布的一项研究结果显示，抗氧化剂和维生素似乎并不能增强人体预防肺癌的能力，这一结果可能会让许多吸烟者大失所望.
相反，新的研究表明对肺癌可能有一些吸烟者希望，抗氧化剂和其他维生素似乎没有提供保障。
在分析了八份以前的研究报告中，研究人员发现，没有证据显示维他命A ， C ， E或叶酸降低一个人的患肺癌的危险。而通过全国研究表明，在成千上万的成年人生活的长达16年来，具有最高摄入的维生素量的人民没有太大的可能性有肺癌,这是相对于那些最低摄入量的人来讲的。
新的报告的带头的作者博士町告诉路透社健康，现在有一种流行的概念，即吸烟者服用维生素补充剂可以抵御肺癌 。
一名哈佛大学医学学院和在波士顿的布莱根妇女医院的助理医学教授博士町说这是不正确的，在我们的研究中证实这种说法，。
她和她的同事们报告的结果可以在国际癌症期刊找到的。
维生素C和E是抗氧化剂，这意味着他们帮助抵消细胞损害的物质是人体内所谓的自由基。维生素A和叶酸，加上B族维生素，也有利于维护正常的健康的细胞功能。
根据町的团队的研究,所有这些维生素已假设有削减肺癌的风险的功能,但研究证据很多参差不齐。尤其是，大多数前瞻性研究-那些后续的人超过时间-没有发现任何明确的保护作用。
但由于这些研究包括只有少数的肺癌病例，他们的研究结果不太可靠。因此，町和她的同事们汇集的数据，从8个前瞻性研究中看到，共有430281成年人在欧洲和北美，包括3 206个有肺癌病人。
之后通过研究人员的吸烟的习惯和其他变数等因素表明，如整体饮食，体重和教育，没有证据表明维他命A ，C ，E或叶酸可以降低患肺癌风险。
在最初的一些证据表明，维生素C来自于食物中，而不是补充，是保护。不过，当研究人员从橙，红辣椒，胡萝卜和其他红橙色的水果和蔬菜的颜色中提取β -隐这种植物化学物时这方面的证据不可靠.
因为很多维生素C丰富的食物含有β -隐，研究人员推测后者的营养可能有助于解释一些研究中发现维生素C和降低肺癌风险的联系。
事实上，它仍然是有可能的,但在营养丰富的水果和蔬菜中如果不是个别的维生素有助于防止肺癌， 博士町说。
她解释到，这些食品可能会赋予的好处时通过组件以外的其他维生素，或通过其独特的组合营养素-虽然，她补充说，在这方面的工作还有许多工作有待据悉。
