A diet that is high in calcium may be associated with a reduced risk of cancer, especially colorectal cancer, according to the results of a study published in the Archives of Internal Medicine.
Colorectal cancer is the second leading cause of cancer-related deaths in the United States. The disease develops in the large intestine, which includes the colon (the longest part of the large intestine) and the rectum (the last several inches).
The role of diet in cancer incidence remains a major focus among researchers as it is becoming more evident that diet may reduce the risk of developing certain types of cancers. Researchers continue to evaluate different foods and supplements and their relationship to different types of cancers.
The NIH-AARP Diet and Health Study was designed to evaluate dairy food and calcium intakes in relation to cancer. Study participants responded to a food frequency questionnaire (FFQ) that allowed researchers to determine their intake of dairy food as well as calcium from other foods and supplements. Over a seven-year period, the researchers identified 36,965 men and 16,605 women with cancer.
There was no relationship between calcium intake and overall cancer incidence in men. In women, the risk of cancer decreased with increasing calcium intake up to approximately 1300 mg/day; however, further increases in calcium intake did not decrease cancer incidence.
In men and women, increased calcium intake was associated with a decreased incidence of cancers of the digestive tract. Men with the highest intake of calcium had a 16% reduction in the incidence of digestive tract cancers compared with men with the lowest calcium intake. Women with the highest intake of calcium had a 23% reduction in the incidence of digestive tract cancers compared with women with the lowest calcium intake. The effect of high calcium intake was the greatest in the prevention of colorectal cancers in both men and women, leading the researchers to conclude that “calcium intake is associated with a lower risk of total cancer and cancers of the digestive system, especially colorectal cancer.”
 Park Y, Leitzmann MF, Subar AF, et al. Dairy food, calcium, and risk of cancer in the NIH-AARP Diet and Health Study. Archives of Internal Medicine. 2009; 169:391-401.