People who drank about two 8-ounce glasses of milk a day had a 15 percent reduction in risk of getting colorectal cancer, according to a study that seems to redeem the benefits of a much maligned beverage.

The new analysis from researchers at Brigham and Women’s Hospital and the Harvard School of Public Health in Boston comes as science continues to search for foods that may play a role in health and disease. Milk, in recent years, has been implicated as a trigger of other forms of cancer.

Reporting in today’s Journal of the National Cancer Institute, researchers found milk may have a protective effect against colorectal cancer, most likely due to its rich calcium content. Daily calcium supplementation of 900 milligrams was also effective, confirming what other studies have shown.

“This study provides additional support to the growing body of evidence that moderate milk and calcium intake may reduce the risk of colorectal cancer,” said Dr. Stephanie Smith-Warner, an assistant professor of epidemiology at Harvard’s public health school and a co-author of the report.

Although participants consumed a variety of dairy products, Smith-Warner and her colleagues found that it was about two 8-ounce glasses of milk a day that significantly reduced risk. Drinking less, or eating other dairy products, did not have the same effect. Milk, she said, tends to be fortified with vitamin D, which also appears to help lower the risk.

People who consumed milk and took calcium supplements had a 22 percent reduction in risk, Smith-Warner said.

The new research re-examined data from 10 previous studies, involving more than 500,000 participants, focusing on calcium consumption and colorectal cancer risk.

Dr. Euyoung Cho, another lead investigator of the project, said while the cause of colorectal cancer remains unknown, “the results of this study have brought us even closer to understanding how to reduce the risk of this disease.”