Calcium supplements, taken with or without vitamin D, may increase the risk of colon polyps, according to the findings of a new study published in the journal Gut.
The secondary analysis of data from a randomised trial of vitamin D and calcium in patients with colorectal adenomas, found that calcium and the combination of calcium and vitamin D increased the risk of sessile serrated adenomas or polyps (SSA/Ps) 6-10 years after supplementation began. Although no increased risk was observed during the 3-5 years that participants consumed the supplements, over the following 6-10 years, calcium alone was associated with an adjusted risk ratio (aRR) of 2.65 (95% CI 1.43-4.91) and calcium with vitamin D had an aRR of 3.81 (95% CI 1.25-11.64). Women and current smokers had higher risks of serrated polyps (SPs) when exposed to supplemental calcium.
While further studies are needed to confirm the results, given that calcium supplements are taken by millions of people around the world, the findings may have important implications for bowel cancer screening and prevention.
Since SPs are important colorectal cancer precursors, the study authors suggest patients with a history of premalignant serrated polyps, especially women and smokers, may wish to avoid vitamin D and calcium supplementation.