Calcium supplements may reduce the risk of colon cancer, according to a new report.

The Calcium Polyp Prevention Study the first randomised, controlled trial to study the effect of calcium on cancer looked at 930 people with a history of colorectal cancer. Participants took 1200 mg calcium or placebo daily for four years. When compared with the placebo group, patients taking calcium had a 15 per cent reduction in adenoma recurrence and developed fewer polyps when adenomas did recur.

The authors speculate that the calcium may have increased the rate of spontaneous disappearance of small adenomas. There was, however, no suggestion that rectal mucosal proliferation (believed to be a biomarker for colon cancer) was altered by calcium (Lancet, 1998; 352: 1683).

More information from the Nurses' Health Study reveals that a daily folate intake of 400 micrograms (ug) or more is associated with a 31 per cent lower risk of developing colorectal cancer.

This remained true after adjustments for age, activity, body mass index, smoking, intake of aspirin, meat and fibre, and family history. Most of the women took their folate in a multivitamin form. Those who relied upon dietary intake alone did not always get the required 400 ug or more (Ann Intern Med, 1998, 129: 517-24).