A recent study published in the International Journal of Epidemiology found a link between dairy milk consumption and an increased risk of breast cancer.
The study, published in 2020, followed over 52,000 women over the course of 8 years. At the beginning of the study, each participant was cancer-free. The women were asked to track and report their food logs for nearly 8 years. The study examined the relationship between soy milk consumption, dairy milk consumption, and breast cancer, and found a link between dairy milk consumption and an increased risk of breast cancer. No link between soy milk consumption and breast cancer was found.
Up until this study, no studies existed with “large numbers of dairy consumers and soy consumers to assess mutual confounding.” At the end of the study, 1,057 of the women had developed breast cancer, with a notable association between dairy consumption and risk of breast cancer.
The study further noticed that “full fat and reduced fat milks produced similar results,” while “no clear associations were found between soy products and breast cancer.”
Soy Milk And Estrogen
Many people avoid soy due to the belief that it contains dangerous levels of estrogen. Some even opt for dairy milk instead, fearful that soy may contribute to breast cancer or other issues. While it’s true that soy does contain isoflavones (a weak plant version of estrogen known as phytoestrogens), the effects of phytoestrogens on the human body are negligible.
According to Harvard, “soy has either a beneficial or neutral effect on various health conditions.” In relation to breast cancer, soy has been shown to have a positive or neutral effect.
Many people avoid soy for fear of the estrogen when soy milk could actually decrease the risk of breast cancer (at best) or make no impact (at worst). On the other hand, dairy milk may make no impact (at best) or increase the chances of breast cancer (at worst).
As the study concluded: “Higher intakes of dairy milk were associated with greater risk of breast cancer, when adjusted for soy intake. Current guidelines for dairy milk consumption could be viewed with some caution.”
Public Perception Is Shifting
As more evidence points to the health risks associated with dairy milk consumption, it seems the public’s view of dairy is also shifting. According to the USDA, dairy milk sales are steadily decreasing and non-dairy options are increasing.
While the majority of North Americans still consume dairy milk, more and more people are turning to plant-based alternatives. Many view options like almond milk and oat milk as healthier alternatives. But soy is still seen as a lesser option.
In reality, soy milk is one of the best dairy alternatives on the market. Almond and oat milk are often low in protein and high in sugar, while soymilk is lower in sugar and has a notable amount of protein. This is especially important when replacing or substituting dairy milk for a non-dairy option.
The general public has a long way to go to ditch dairy milk completely, but studies like this and the reports on consumption decreasing are promising.