Cancer researchers urged people on Wednesday to take more vitamin D to lower their risk of colon, breast and ovarian cancer, saying studies showed a clear link.

"Our suggestion is for people to increase their intake," through diet or a vitamin supplement, Dr. Cedric Garland said in a telephone interview.

Garland's research team reviewed 63 studies, including several large long-term ones, on the relationship between vitamin D and certain types of cancer worldwide between 1966 and 2004.

He said the benefit of vitamin D was as clear as the harmful link between smoking and lung cancer.

"There's nothing that has this ability to prevent cancer," he said, urging governments and public health officials to do more to fortify foods with vitamin D.

Garland is part of a University of California at San Diego Moores Cancer Center team that published its findings this week online in the American Journal of Public Health.

The paper concluded that vitamin D deficiency may account for several thousand premature deaths from colon, breast, ovarian and other cancers annually.

Vitamin D is found in milk, as well as in some fortified orange juice, yogurt and cheeses, usually at around 100 international units (IU) a serving.

People might want to consider a vitamin supplement to raise their intake to 1000 IUs per day, Garland said, adding that it was well within the safety guidelines established by the National Academy of Sciences.

The authors said that taking more vitamin D could be especially important for people living in northern areas, which receive less vitamin D from sunshine.

African Americans, who don't produce as much of the vitamin because of their skin pigment, could also benefit significantly from a higher intake, the authors said.

　　美国研究人员12月28日表示，人们在日常饮食中应多摄入一些维生素D，以降低自身患结肠癌、乳腺癌和卵巢癌的危险。因为多项研究结果显示，维生素D和人们患癌危险之间具有明确的关系。

　　据路透社12月28日报道，美国加利福尼亚大学的医学教授塞德里克·加兰德博士是该项目的研究人员之一。他的研究小组回顾了63项相关研究。这些都是1966年至2004年间，各国关于维生素D和某些癌症间关系的研究，其中还不乏一些大型的、长期研究项目。

　　加兰德说，维生素D能给人们带来好处就像是吸烟能引发肺癌一样，这两者都是非常明确的。而维生素D摄入量不足则会导致全球每年有数千人因患结肠癌、乳腺癌、卵巢癌和其它一些癌症过早地死亡。

　　因此，加兰德号召人们补充每天的维生素D摄入量，他说：“我们建议人们增加维生素D的摄入量”，这可以通过日常饮食或者服用维生素补充剂来实现。

　　研究人员说，牛奶、一些加强了营养成分的果汁、酸奶和奶酪中的维生素D含量普遍约为100国际单位/每份。因此，人们可以考虑服用补充剂将自己的维生素D摄入量提升至每天1000国际单位（25微克）。而这一摄入量也符合美国国家科学院制定的相关安全指导方针。

　　研究人员还表示，摄入更多的维生素D对于那些生活在美国北部地区的人们来说，显得尤其重要，因为那里的人们因日晒少而获取的维生素D量都比较少。

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