Cancer Research Lab

Calcium, vitamin D supplements and dairy products are protective against colorectal cancer, according to findings published in the March issue of the American Journal of Epidemiology.

“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. “A possible protective effect of calcium and vitamin D against colorectal carcinogenesis has been suggested from results of in vivo and in vitro studies.”

Dr. Park and co-investigators examined the association between calcium and vitamin D intake and the risk of colorectal cancer in 191,011 participants of the Multiethnic Cohort Study. The subjects were between the ages of 45 and 75 years, and completed a quantitative food frequency questionnaire between 1993 and 1996.

During an average follow-up of 7.3 years, a total of 2110 incidence cases of colorectal cancer were identified (1138 in men and 972 in women).

An inverse association was observed between total calcium intake (from food and supplements) and the risk of colorectal cancer in both men and women. The relative risks (RRs) for the highest versus the lowest quintile were 0.70 (p = 0.006) and 0.64 (p = 0.003) in men and women, respectively.

“Total vitamin D intake was inversely associated with colorectal cancer risk in men but not in women,” Dr. Park’s team reports. The RR for the highest quintile was 0.72 (p for trend = 0.03) in men and 0.89 (p for trend = 0.80) in women.

An inverse association was also found between intake of dairy products and colorectal cancer risk. This was especially true among nonusers of supplemental calcium — RR = 0.77 in men and RR = 0.66 in 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.