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　　Fish oil supplements are a popular way to increase the intake¹ of omega-3 fatty acids, which are thought to have a wide range of beneficial effects, particularly for cardiovascular health. But are they effective in preventing cancer? A new study suggests the answer is … maybe.
服用鱼油营养补充剂，是增加欧米加-3脂肪酸摄取量的一种常用方式。欧米加-3被认为对健康有广泛的益处，特别是有益于心血管健康。但是，这些好处是否也包括预防癌症呢？一项新的研究显示，答案是“也许”。
Women in the study — 35,000 of them — were asked in a questionnaire whether they used fish oil supplements. Six years later, those who did were much less likely to have had breast cancer.
参加研究的3万5千名女性首先被问及她们是否服用鱼油。6年之后，服用鱼油的女性罹患乳癌的比例比不服用鱼油的女性要低得多。
"We found that women who were using fish oil at the time that they entered the study had a 32 percent lower risk of breast cancer than women who did not use fish oil supplements," said study leader Emily White of the Fred Hutchinson Cancer Research Center in Seattle.
主持这项研究的埃米莉·怀特说：“我们发现，这些研究开始时就在服用鱼油营养补充剂的妇女罹患乳癌的风险，比不服用鱼油的妇女低百分之32。”怀特在弗雷德·赫钦森癌症研究中心工作。
She says there's good reason to suspect that omega-3 fatty acids might protect against cancer. "There's a strong evidence that cancer is related to inflammation. So fish oil fits into that mechanism², since it is an anti-inflammatory drug."
她说，有理由设想欧米加-3脂肪酸可能有助于预防癌症：“有非常有力的证据，证明癌症和炎症有关。而鱼油是一种抗炎剂，因此可见它在其中的作用。”
Despite the evidence, White doesn't think her study alone justifies³ a recommendation that women start taking fish oil capsules.
尽管有这个证据，但怀特并不认为仅仅靠她的研究，就足以建议女性开始服用鱼油胶囊。
"No, I don't think that a single study can lead to public health recommendations to start taking supplements," she says. "Really, we need randomized trials, where people are assigned to take a supplement versus⁴ not, to answer whether a pill would be useful to take for cancer prevention."
她说：“我不认为仅仅根据一项研究，就可以提出服用鱼油营养补充剂的公共卫生建议。实际上，我们需要做随机临床试验，随机指定参与研究的人服用或不服用营养剂，由此得到营养补充剂是否有助于预防癌症的答案。”
White explained that in a randomized trial, participants would be randomly⁵ assigned to either take the supplements or not.
怀特说，在随机试验中，参与研究者被随机指定服用或不服用营养剂。
By contrast, her study is what is known as an observational study, where participants themselves decide, in this case, whether to take a fish oil supplement, and then the researchers observe them to see who develops cancer. But the women who chose to use a supplement could be different in many other ways from those who didn't.
她的研究方法与此相反，那是一种观察式的研究。由参与者自行选择要不要服用鱼油补充剂。然后研究人员观察她们，注意谁会患癌症。不过，选择服用鱼油补充剂的妇女，也可能和不服用鱼油的妇女，还有许多其它方面的不同。
White and her colleagues did try to factor those differences into their analysis, but scientists generally prefer a randomized study, and researchers at Harvard are now organizing one to study the effects of both omega-3 fatty acids and vitamin D.
怀特和她的同事们曾经尝试把各方面的不同因素纳入分析研究。不过，科学家们通常更愿意采用随机研究的方式。哈佛大学的研究人员也正在准备展开对欧米加-3 和维生素D的效果的研究。
White's paper is published in the journal Cancer Epidemiology, Biomarkers & Prevention.