Drinking lots of milk may lower the risk of colorectal cancer

Drinking lots of milk and increasing your calcium intake may lower the risk of colorectal cancer, according to a new study that appears in the July 7 issue of the Journal of the National Cancer Institute.

Colorectal cancer is a disease resulting from mutations in epithelial cells of the gastrointestinal tract. Most of the known abnormalities involve the DNA which regulates cell growth. Though many of these effects are well known, there are likely environmental, hereditary, and viral causes for specific cell defects. Because the changes at the cell level may take years to develop into cancer, it is generally impossible to track the cause of specific cases of cancer. Thus efforts at prevention mostly focus on avoiding or identifying risk factors and early detection.

It is the third most common form of cancer and the second leading cause of death among cancers in the United States.

To better assess the relationship between consumption of dairy foods, calcium intake, and colorectal cancer risk, Eunyoung Cho, Sc.D., of Brigham and Women's Hospital and Harvard Medical School in Boston, and colleagues conducted a pooled analysis of 10 cohort studies from five countries. The studies included more than half a million individuals, among whom nearly 5,000 individuals were diagnosed with colorectal cancer during follow-up.

Among all of the food sources of calcium that the researchers examined, only milk consumption was associated with a decreased risk of colorectal cancer, particularly cancers of the distal colon and rectum. The risk decreased with increasing milk consumption; compared with people who consumed less than 70 grams/day (about 2.5 ounces) of milk, people who consumed 175-249 g/day (6.2-8.9 oz.) had a 12% reduction in risk of colorectal cancer and people who consumed more than 250 g/day (8.9 oz.) had a 15% reduction in risk. Each two 8-oz. glasses per day (500 g/day) increase in milk consumption was associated with a 12% decrease in risk.

The study also found that higher total calcium intake was associated with a decreased risk of colorectal cancer. Increasing calcium intake to 1000 mg/day or more could result in 15% fewer cases of colorectal cancer in women and 10% fewer cases in men, according to the authors.

"These data, in combination with the previous experimental studies documenting a salutary effect of calcium supplementation on colonic epithelial cell turnover and colorectal adenoma recurrence, support the concept that moderate milk and calcium intake reduces the risk of colorectal cancer," the authors write.

http://jncicancerspectrum.oupjournals.org/