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Vitamin D cuts colon cancer death risk: U.S. study

Oct 31, 2007 | Will Dunham | Yahoo News

People with higher vitamin D levels are less likely to die of colorectal cancer, researchers said on Tuesday, but the vitamin does not appear to affect the chances of dying from any other type of cancer.

A number of studies have found protective effects from higher intake of vitamin D for cancer and other ailments.

A team led by U.S. National Cancer Institute epidemiologist Michal Freedman sought to determine whether vitamin D can reduce a person's chances of dying from various cancer types.

The researchers tracked 16,818 people who joined a nationwide U.S. government health survey between 1988 and 1994, following them through 2000. Among them, 536 died of cancer.

The participants provided blood samples that the researchers used to determine the level of vitamin D in their blood.

People with higher levels of vitamin D when they entered the study had about a 72 percent reduced risk of dying from colorectal cancer compared to those with the lowest levels of vitamin D, the researchers reported in the Journal of the National Cancer Institute.

The body makes vitamin D when skin is exposed to sunlight. Not many foods are naturally rich in it. It is found in fatty fish such as salmon and milk commonly is fortified with it.

The researchers saw no link between vitamin D levels and the overall risk of dying from cancer, including lung, prostate, breast, non-Hodgkin lymphoma and leukemia.

"We didn't find a relationship between the circulating vitamin D levels and total cancer mortality. And that was true for men and women and the racial and ethnic groups we looked at," Freedman said in a telephone interview.

"The part about colorectal cancer is consistent with some other studies and is intriguing," she added.

Colorectal cancer refers to cancer that starts in the colon or rectum. It kills about 50,000 people annually in the United States alone.

The researchers said previous research showed that vitamin D may have characteristics that could protect against cancer such as reducing tumor growth and inducing cancer cell death.

The National Cancer Institute is part of the U.S. National Institutes of Health.

NIH experts Cindy Davis and Johanna Dwyer, in an editorial accompanying the study, noted that vitamin D is best known for strengthening bones and preventing rickets, a disease that causes soft, weak bones in children.

"While vitamin D may well have multiple benefits beyond bone, health professionals and the public should not, in a rush to judgment, assume that vitamin D is a magic bullet and consume high amounts of vitamin D. More definitive data on both benefits and potential adverse effects of high doses are urgently needed," Davis and Dwyer wrote.