Calcium supplements might help in protecting against the development of colon polyps, which can become cancerous. This benefit persists up to 5 years after people stop taking the supplements. Researchers from the Dartmouth Medical School in Lebanon, New Hampshire found that there is epidemiological and experimental data suggesting the a high intake of calcium may decrease the risk of colorectal cancer. Data from the Calcium Polyp Prevention Study in 1999, which involved 930 adults, who were randomly assigned to take an inactive placebo or 1200 milligrams calcium daily for 4 years, showed a 20 per cent reduction in the risk of all colorectal cancers with calcium supplementation. Eight hundred and eighty two of the original participants were followed for at least 5 years after the end of the treatment phase of the study. During that period, there was a 41 per cent reduction in the risk of polyps and a 35 per cent reduction in risk of all colon cancers. These were more pronounced reductions than were seen during the treatment phase. This reduction in risk persisted beyond 5 years after the calcium supplements were stopped. The data indicates that calcium is effective in reducing the risk of colorectal adenomas and there is no rebound in risk after the end of the supplementation. In fact there appears to be a delayed, more pronounced suppression of colorectal neoplasia during the 5 years after treatment.
American Association for Cancer Research,
April 2005