Vitamin D does not reduce overall cancer mortality

Several epidemiological studies have supported the theory that vitamin D can reduce cancer mortality by decreasing cancer incidence or improving survival. Animal and cell studies suggest that vitamin D may reduce tumor growth and induce cancer cell death.

In order to find any association between cancer mortality and elevated levels of vitamin D, D. Michal Freedman, Ph.D., of the National Cancer Institute in Bethesda, Md., and colleagues analysed data of 16,818 individuals, 17 years old and older. The follow up was 10 years, during which time 536 individuals died of cancer.

Results showed that cancer mortality was not related to the level of circulating vitamin D for the overall group, nor was it related when the researchers looked at the data by sex, race, or age.

But higher levels of vitamin D were associated with a 72 percent reduced risk of colorectal cancer mortality, compared with lower levels.

"To our knowledge, this study is the first to examine the relationship between measured serum vitamin D levels and cancer mortality for selected site and for all sites combined," the authors write.

Cindy Davis, a program director in the NCI nutrition sciences research group and co-author of an accompanying editorial said that these numbers can't be taken to mean that vitamin D prevents colorectal cancer because the study was not large enough and didn't run long enough to provide definitive information.

"These findings must be put into the context of total diet and lifestyle. There are many risk factors other than diet for colorectal cancer, and there are many possible dietary risk factors other than vitamin D that have been linked to cancer risk," she wrote.

The study is published online in the Journal of the National Cancer Institute. (ANI)

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