A dietary and supplemental intake of calcium and vitamin D is not associated with increased risk of colorectal cancer in women, according to a Harvard University/Brigham & Women's Hospital study.

"In vivo and in vitro studies have suggested a protective role of calcium and vitamin D in the development of colorectal cancer. However, epidemiologic data have been inconclusive. The authors prospectively assessed intakes of calcium and vitamin D in relation to risk of colorectal cancer in a large, prospective, female cohort from the U.S. Women's Health Study," wrote J. Lin and colleagues.

"In 1993, 39,876 women aged greater than or equal to 45 years and free of cardiovascular disease and cancer were enrolled in the study. During an average follow-up of 10 years, 223 of 36,976 women eligible for the present study developed colorectal cancer. Intakes of calcium and vitamin D from dietary sources and supplements were assessed with a baseline food frequency questionnaire. Cox proportional hazards regression was used to estimate relative risks and 95% confidence intervals," the researchers said.

"Intakes of total calcium and vitamin D were not associated with risk of colorectal cancer,” they determined; “multivariate relative risks comparing the highest with the lowest quintile were 1.20 (95% confidence interval: 0.79, 1.85; p for trend=0.21) for total calcium and 1.34 (95% confidence interval: 0.84, 2.13; p for trend=0.08) for total vitamin D."

They added, "Intakes of both nutrients from specific types of sources, including diet and supplements, were also not significantly associated with colorectal cancer risk."

Lin and coauthors concluded, "Data provide little support for an association of calcium and vitamin D intake with colorectal cancer risk."

Their study was published in American Journal of Epidemiology (“Intakes of calcium and vitamin D and risk of colorectal cancer in women.” Amer J Epidemiol, 2005;161(8):755-764).

For additional information, contact J. Lin, Harvard University, School of Medicine, Brigham & Women's Hospital, Division Prevention Med, Dept. of Med, 900 Commonwealth Avenue E, Boston, MA 02215.