Breast Cancer Prevention Part II: 

Dairy and Soy - The Impacts on Breast Cancer

Dairy and Breast Cancer

Dairy is in many products and consumed daily by the masses, however, most are simply uninformed on the true dangers of dairy. Avoiding diary products is key in breast cancer prevention.  Many scientific, peer-reviewed studies illustrate that dairy intake increases risk for breast cancer, including a meta-analysis that included over 1.6 million women. While dairy products contain calcium and vitamin D, which have preventative properties, they also contain compounds that significantly increase the risk of breast cancer, effectively making the protective effects of calcium and vitamin D null.

Perhaps the most dangerous compound in dairy is IGF-1, or insulin like growth factor-1. IGF-1 is a hormone that helps promote tissue development; while IGF-1 is fine in a normal setting, it is far from that when we are talking about incidence of cancer; in this scenario, IGF-1 causes cancer growth, and that is why dairy intake should be minimized to reduce the risk of breast cancer. Moreover, dairy products are high in estrogen, which expedites cancer progression in those with estrogen receptor positive sub-types of breast cancer. Both IGF-1 and exogenous estrogen pose health risks to those with existing breast cancer risk factors.

Continuing, the other issue with dairy is the high fat content. Dairy, just like most other animal products, is high in saturated fat. Saturated fat increases chances of heart disease, stroke, and various cancers, so it is important to watch intake of this as well. While using low-fat dairy products was deemed safer than full-fat dairy, there is strong evidence showing the risk of cancer is still elevated even with lower fat dairy intake.

Furthermore, a recent study by the National Cancer Institute stated that women who consume the most American, cheddar, and cream cheeses had a 53% increased risk for breast cancer. That being said, it may be time for us to trade in our regular milk for almond milk and through simple changes like that, reduce our risk of certain cancers, including breast cancer.

 Breast Cancer and Soy

Another topic to address is soy. Over the years, soy has gotten a bad reputation for playing a role in the development of breast cancer because it is thought to increase estrogen levels. The confusion behind this is due to the term phytoestrogens - soy foods contain compounds called isoflavones. Isoflavones, on a molecular level, have similar structure to human estrogen. And there, the term phytoestrogen was born. Phyto meaning plant, estrogen meaning estrogen...phytoestrogen.

That being said, these isoflavones do not inherently increase breast cancer risk, especially when we’re talking ingestion of natural soy containing foods. In fact, a Chinese study with 73 thousand women illustrated that having a soy rich diet from a young age decreases breast cancer risk by 11%, compared to starting to eat soy foods later in life. 

The most important takeaway here is that we are talking about natural foods that contain soy. When we change that discussion to talking about soy supplements, the outcome is different. Soy supplements are much higher in isoflavones, and in this scenario, we have an increased risk of breast cancer. So bottom line, minimize supplements - try to get everything from whole foods!