A research study funded by the National Cancer Institute and the World Cancer Research Fund in the UK has raised alarms regarding cow's milk consumption.
In a North American study, researchers analyzed data from a group of over 50,000 women over an eight-year period. During this time, the women were asked to fill out surveys about their dietary habits, with half of the women following a vegetarian diet and consuming soy milk, while the others consumed cow's milk.
The researchers adjusted for all factors influencing cancer risk, such as alcohol consumption, physical activity, hormones, and reproductive history. The trial aimed to determine the relationship between soy consumption and breast cancer, as explained by Gary E. Fraser, the lead author of the study.
Among the participants, all of whom were cancer-free at the start of the study, 1,057 developed breast cancer. The team could not establish a link between soy and breast cancer; however, the results indicated that cow's milk was the culprit.
The study suggested that "drinking cow's milk daily, even in small amounts, can increase the risk of breast cancer by up to 80%." Dr. Fraser from the Loma Linda University School of Public Health and Medicine said, "We found that when consuming relatively low doses of dairy milk, less than a cup a day, there was a sharp increase in breast cancer risk."
He added, "With one cup of milk a day, we observed a risk increase of over 50%, and with two to three cups a day, the risks rose to between 70% and 80%. This effect can be attributed to natural stimulants present in dairy milk that promote cell growth and division, which is a typical mechanism for cancer. These stimulants elevate growth factor levels, which strongly contribute to breast cancer development. However, due to the observational design of the study, it could only suggest a relationship between cow's milk consumption and breast cancer, rather than confirm a causal effect."
Some studies have indicated that dairy products may increase the risk of breast cancer, while others have found that they may reduce it. Researchers believe that further high-quality studies are needed to understand the true impact of cow's milk on cancer risk, according to the British newspaper, Express.
