Calcium and Vitamin D Supplementation Increased Colorectal Cancer Precursors

A randomized chemoprevention study in the US found evidence that calcium and vitamin D supplementation increased the risk of sessile serrated adenomas or polyps (SSA/Ps), precursor lesions for colorectal cancer. A total of 2259 participants with one or more adenoma at baseline were randomized to receive 1200 mg/day of elemental calcium, 1000 IU/day of vitamin D3, both or neither agent for 3 or 5 years. Serrated polyps (SPs) were diagnosed in 565 of 2058 (27.5%) participants during the treatment phase and 329/1108 (29.7%) during the observational phase thereafter. In total, 211 SSA/Ps were identified during follow-up. In the treatment phase, there was no effect of either calcium or vitamin D on incidence of SSA/Ps. However, during the later observational phase (6–10 years after supplementation began), there were elevated risks of SSA/Ps associated with calcium alone and calcium+vitamin D treatment (adjusted risk ratios 2.65 and 3.81, respectively). Women and current smokers had higher risks of SPs when exposed to supplemental calcium. The risks must be weighed against the benefits of calcium and vitamin D supplementation. Other known risk factors for SSA/Ps include tobacco, alcohol use, white race and obesity. Source: http://gut.bmj.com/