Calcium supplementation may increase risk of colon polyps, study finds

08 Mar 2018 --- Researchers have found evidence that taking calcium supplementation, with or without vitamin D supplementation, increases the risk of developing polyps, important colorectal cancer precursors. However, these possible risks must be weighed against the benefits of calcium and vitamin D supplementation, with the increased cancer risk appearing between six and ten years after supplementation begins.

The study, published online in the British Medical Journal Gut, notes that patients with a history of premalignant serrated polyps, especially women and smokers, may wish to avoid vitamin D and calcium supplementation.

If calcium and its combination with vitamin D is truly associated with increased risk of premalignant polyps, this has important public health implications, the study authors note. 

“Calcium and vitamin D supplements are taken by roughly 40 percent of the US population, which equates to over 100 million [people]. Women represent the majority of those taking calcium supplements in the general population. It is interesting therefore that [polyps] are at least as common if not more common in women than men, in contrast to conventional adenomas, which are more common in men.”

In response to the new study, the Council for Responsible Nutrition (CRN), a US trade association for the dietary supplement and functional food industry, stated it was “surprised” and called for additional research to verify the study’s outcomes.

“CRN is surprised by the results of this new study as previous research has indicated calcium supplementation may have a protective effect against colorectal polyps,” says Andrea Wong, Ph.D., vice president, scientific & regulatory affairs, CRN.

“Even the study’s authors acknowledge they do not understand the mechanism by which the calcium supplements seemingly had the opposite effect of what was hypothesized. Given these opposing outcomes in the research to date, this is clearly a case where additional research is needed to discern whether this study’s outcome was an anomaly,” she adds.

Until further research is conducted, CRN cautions the medical community and consumers against haphazardly dismissing or downplaying the value of calcium supplementation, particularly in people most likely to develop osteoporosis or bone loss. 

“This particular study focused on a very specific population—patients with a history of colorectal polyps—and therefore, the study’s results are not applicable to the general population. We recommend consumers with a history of colorectal polyps talk with their doctors about whether calcium supplementation is appropriate,” Wong concludes.