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 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.