Drinking Dairy Ups Your Risk of This Cancer by 80 Percent, Study Finds

There are many reasons why you may not include dairy in your diet, but is fear of elevated cancer risk one of them? New research indicates that drinking just one glass of milk each day could dramatically increase a woman's chances of developing breast cancer.

A new study commissioned by the National Cancer Institute at the National Institutes of Health and the World Cancer Research Fund found that women who drink cow's milk could increase their risk of breast cancer by as much as 80 percent in comparison with women who drink soy milk. 

Nearly 52,800 females participated in this 7-year-long study—which compared the health outcomes of women who drank cow's milk versus those who drank soy—all of which had previously been involved in the Adventist Health Study-2. An important detail, seeing as Adventists typically abide by a vegetarian diet and also tend to eat a lot of soy products compared to those who follow the Standard American Diet.

Upon enrollment, all women were asked to fill out a detailed food questionnaire and a small group was selected to provide 24-hour food journals and urine samples periodically throughout the study. The results were shocking—more than 1,000 participants had developed breast cancer by the end of the study.

Researchers found that women who reported drinking eight ounces of cow's milk each day escalated their cancer risk by 50% and those who drank two to three cups of the stuff per day increased their risk by up to 80%. Of course, this information doesn't suggest that drinking one cup of cow's milk per day makes a woman 50% more likely to develop breast cancer. Instead, this finding suggests that cow's milk increases a woman's individual risk by 50%. For example, the average risk for a woman developing breast cancer is about 12%. So, for a woman who falls in line with the average, her risk would elevate by 50% if she drank about 8-ounces worth of dairy each day.

As for the women who didn't drink cow's milk but drank soy milk, they didn't show any indications of increased risk of cancer. In fact, The American Cancer Society says many studies currently suggest that soy-based foods such as soy milk, tempeh, tofu, and miso may lower the risk of breast cancer.