Approximately 50 percent of Americans are vitamin D deficient. Previous studies have found that vitamin D supplementation can lower the risk of certain cancers. However, the Women's Health Initiative study found that low doses of vitamin D did not lower the risk of colon cancer. Now a meta-analysis reports that higher doses of vitamin D may prevent up to two-thirds of colon cancer cases. A meta-analysis examines similar studies to reveal trends that may not be evident from just one study.
The meta-analysis, published in the American Journal of Preventive Medicine, investigated whether vitamin D levels are associated with colon cancer risk. Researchers at the University of California San Diego, analyzed the data of five studies including 1,448 healthy adults tested for vitamin D. The participants were followed for up to 25 years. The meta-analysis included data from the Women's Health Initiative study.
The researchers found that the risk of colon cancer significantly decreased with increasing levels of vitamin D. Serum levels of vitamin D at 34 nanograms per milliliter reduced the risk of colon cancer by 50 percent. The authors suggest that vitamin D at 46 nanograms per milliliter, or a daily intake of 2,000 IU of vitamin D3, would reduce the risk of colon cancer by two-thirds.
"The evidence to date suggests that daily intake of 1000-2000 IU/day of vitamin D(3) could reduce the incidence of colorectal with minimal risk," the study authors conclude.
REFERENCES:
1. Gorham ED et al. Optimal vitamin D status for colorectal cancer prevention: a quantitative meta analysis. Am J Prev Med. 2007 Mar;32(3):210-6.
Posted by Elaine Gavalas on February 27, 2007 03:29 PM
