Cancer prevention, calcium and vitamin D

The two nutrients work well together, but not separately, researchers say

Published January 12, 2004; Category: DARTMOUTH MEDICAL SCHOOL

The nutrients calcium and vitamin D work in tandem, not separately, to reduce the risk of colorectal cancer, according to a new Dartmouth Medical School study reported in the Dec. 3 issue of Journal of the National Cancer Institute.

The research builds on a multicenter study led by John Baron, Professor of Medicine and of Family and Community Medicine, that found that people who take calcium supplements have a lower risk of adenoma polyps - benign tumors that are precursors to colon or rectal cancer. Now Baron; lead author Maria V. Grau, a research associate at DMS; and colleagues have re-analyzed that study to examine how calcium and vitamin D interact to lower the possibility of colorectal cancer.

More than 800 people participated in the Calcium Polyp Prevention Study, a four-year randomized trial conducted through the Norris Cotton Cancer Center. That study documented the benefits of calcium supplementation for preventing the growth of the benign tumors.

The new analysis found that calcium supplements prevented adenomas only among poeple with higher-than-average baseline vitamin D levels, and serum vitamin D levels were associated with reduced adenoma recurrence only among those taking calcium supplements. The authors write that "further investigation is needed to understand the mechanistic basis of the vitamin D/calcium interaction and to clarify the amount of intake of each nutrient required."

The vitamin D assays were all conducted at the UCLA Center for Human Nutrition. Other coauthors are: Michael Beach of Dartmouth; Robert Sandler, University of North Carolina; Robert Haile, University of Southern California; Timothy Church, University of Minnesota; and David Heber, UCLA.

By HALI WICKNER