Every year, approximately 11,500 women die from breast cancer in the UK, with the disease now being the fourth most common form of cancer death in the country. With a new study by Loma Linda University Health suggesting a correlation between breast cancer and dairy milk, we ask ourselves – is it time to ditch the dairy?
The study “Dairy, soy and risk of breast cancer: Those confounded milks”, published in the International Journal of Epidemiology, suggests that even modest amounts of dairy milk consumption can increase the risk of breast cancer in women by 80%.
The study followed a sample pool of 52,795 North American women, (29.7% were Black), who were initially free of cancer, for 7.9 years. Their dietary intakes were closely monitored with food frequency questionnaires and 24-hour recalls. They also completed a baseline questionnaire about their demographics, family history of breast cancer, physical activity, alcohol consumption, hormonal or any other medication intake, breast cancer screening and reproductive and gynaecological history.
When the study concluded, 1,057 new cases of breast cancer were found and when comparing the women with lower or no milk consumption to the ones with higher intake of dairy calories, it was concluded that dairy milk was indeed associated with a greater risk of breast cancer, independent of any soy intake.
So, what’s causing dairy to increase the risk of breast cancer?
As per biological studies, cow’s milk stimulates cell growth and division and these characteristics act in the body by raising levels of a growth factor called IGF1 (insulin-like growth factor 1). Studies show that in humans, it’s these raised levels of IGF1 that are assumed to increase breast cancer risk. It is important to note that fermented dairy products like yoghurt and cheese do not raise these levels as they are lost during the production process.
Here’s what the first author of the study, Gary E. Fraser, MBChB, PhD, has to say:
There is “fairly strong evidence that either dairy milk or some other factor closely related to drinking dairy milk is a cause of breast cancer in women. Consuming as little as 1/4 to 1/3 cup of dairy milk per day was associated with an increased risk of breast cancer by 30%. By drinking up to one cup per day, the associated risk went up to 50%, and for those drinking two to three cups per day, the risk increased further to 70% to 80%. Dairy milk does have some positive nutritional qualities but these need to be balanced against other possible, less helpful effects. This work suggests the urgent need for further research.”