Colon Cancer: Vitamin D, Calcium Supplements Do Not Lower Risk

Previous studies have suggested that calcium and vitamin D could help to lower the risk of colon cancer.

Yet new findings published in the New England Journal of Medicine (NEJM) show that these dietary supplements are not helpful in lowering cancer risk--particularly when it comes to preventing future polyps.

"Prior observational studies suggested that low levels of vitamin D in humans may increase risk of colorectal cancer, but in the more rigorous setting of a randomized placebo-controlled trial, we found that vitamin D and calcium supplementation did not reduce the risk of colorectal adenomas, which are cancer precursors".

During the study, researchers at the University of Colorado Cancer Center studied 2,259 patients 45 to 75 at 11 academic medical centers who went through a complete colonoscopy and successfully had all colorectal polyps removed.

From there, researchers further the participants divided into four groups : one group received vitamin D, another received calcium carbonate and then another group received vitamin D and calcium carbonate. The fourth group served as a control and were not given anything.

During a follow-up screening, 43 percent of participants were found to have one or more adenomas. Furthermore, those in the placebo group had the same risk of recurring polyps as those in the calcium, vitamin D or combined groups.

"Daily supplementation with vitamin D3 (1000 IU), calcium (1200 mg), or both after removal of colorectal adenomas did not significantly reduce the risk of recurrent colorectal adenomas over a period of 3 to 5 years," concluded lead study author Dr. John Baron, professor of medicine at the University of North Carolina School of Medicine.

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