Calcium and dairy food intakes and colorectal cancer

Nutrition Research Newsletter, April, 2006

Calcium may offer protection against colorectal cancer through possible biological mechanisms. One study suggested that calcium binds secondary bile acids and fatty acids in the colonic lumen, thereby diminishing the potential proliferative stimulus of these compounds on the colonic mucosa. Calcium may also reduce the risk of colorectal cancer by direct effects on cellular proliferation, differentiation, and apoptosis.

Recent epidemiologic studies have generally reported a modest inverse association between calcium intake and the risk of colorectal cancer. However, findings pertaining to specific subsites in the colorectum have been conflicting. A recent study published in the American Journal of Clinical Nutrition examined in detail total calcium (from food and supplements) and dairy food intakes in relation to incident colorectal cancer, overall and by anatomic subsite.

In 1997, 45,306 men aged 45 years to 79 years and without a history of cancer completed a FFQ. The men were followed through December 31, 2004. The men also indicated their use of calcium supplements and multivitamins according to the duration and number of tablets taken per week. Incident cases of colorectal cancer were identified by computerized linkage of the study to the National Swedish Cancer Register and the Regional Cancer Register.

During a mean follow-up of 6,7 years, 449 incident cases of colorectal cancer were found. Total calcium intakes were inversely associated with the risk of colorectal cancer. A high consumption of dairy food was also associated with a lower risk of colorectal cancer. The multivariate rate ratio (RR) of colorectal cancer for > 7 servings/day of total dairy foods compared with more than two servings/day was 0.46. For cancer subsites, the corresponding RRs were 0.37 for proximal colon, 0.43 for distal colon, and 0.48 for rectum.

The results provide support for inverse associations between intakes of calcium and dairy foods and the risk of colorectal cancer. This study had much strength including a population-based and prospective design and detailed information on diet. Future studies should examine the relation of other compounds of dairy foods, such as conjugated linoleic acid, sphingolipids, and milk proteins, with the risk of colorectal cancer.

Susanna C Larsson, Leif Bergkvist, Jorgen Rutegar, et al. Calcium and dairy food intakes are inversely associated with colorectal cancer risk in the cohort of Swedish men. Am J Clin Nutr; 83:667--673 (March 2006) [Reprints not available. Address correspondence to SC Larson, Division of Nutritional Epidemiology, National Institute of Environmental Medicine, Karolinska Institutet, PO Box 210, SE-171 77 Stockholm, Sweden. E-mail: susanna.larsson@ki.se]