Researchers conducting a meta-analysis of 10 studies tracking nutritional consumption of half a million people found that consuming a glass of 6 to 8 ounce of milk was correlated with a 12 percent lower risk of developing colorectal cancer. Those who drank more than a glass a day had a 15 lower relative risk of colorectal cancer. The study was published in the National Cancer Institute Journal.
So should you rush out and start drinking milk in order to reduce your risk of colorectal cancer?
Well, even with such a large group, this is still a very small level of risk reduction by epidemiological standards. As the National Cancer Institute Journal noted in a June editorial,
Where are we, then, with respect to population-level evidence for the calcium–colorectal cancer hypothesis? We have increasingly consistent observational epidemiologic evidence from studies with colorectal cancer end points. We cannot, though, definitively rule out confounding as an explanation for the modest inverse associations seen in these observational epidemiologic studies.
Interestingly, the largest gains for reducing colorectal cancer were among people who took calcium supplements, but the researchers have concerns that high doses of calcium obtained this way could contribute to prostate cancer.
Sources:
Milk may lower risk of colorectal cancer. Associated Press, July 6, 2004.
Milk helps prevent colon cancer. Health Day, July 6, 2004.
Advancing the Calcium–Colorectal Cancer Hypothesis. Arthur Schatzkin and Ulrike Peters, Journal of the National Cancer Institute, June 16, 2004.