Calcium, vitamin D may ward off colorectal cancer

NEW YORK (Reuters Health) - People who consume relatively high levels of calcium and dairy products and take vitamin D supplements seem to be protected to some degree against colorectal cancer, researchers have found.

"Colorectal cancer is one of the most commonly diagnosed cancers worldwide, and dietary factors are considered to be important in its risk," Dr. Song-Yi Park, of the University of Hawaii, Honolulu, and colleagues write in the American Journal of Epidemiology.

Park's team examined the association between calcium and vitamin D intake and the risk of colorectal cancer in 191,000 subjects between the ages of 45 and 75 years, who completed a food frequency questionnaire between 1993 and 1996.

During an average follow-up of 7 years, a total of 2110 new cases of colorectal cancer were identified -- 1138 in men and 972 in women.

High total calcium intake (from food and supplements) lowered the risk of colorectal cancer in both men and women. Comparing the highest calcium intakes with the lowest, the risk of developing colorectal cancer was reduced by 30 percent for men and by 36 percent for women.

"Total vitamin D intake was inversely associated with colorectal cancer risk in men but not in women," Park and colleagues report.

A high intake of dairy products also reduced the risk of colorectal cancer risk, especially for people who didn't take supplemental calcium; the risk reduction was 23 percent for men and 34 percent for women.

"These findings support the hypothesis of protective roles for calcium, vitamin D and dairy products in the risk of colorectal cancer," the researchers conclude.

SOURCE: American Journal of Epidemiology, March 2007.