Is Soy Milk Bad for Breast Cancer Recurrence Rates?

Few dietary recommendations garner as much controversy as soy.  Even more complicated is trying to decide if soy milk is bad for breast cancer recurrence.

If you just run an Internet search for “soy”  you will get results back that suggest that soy products will cause men to grow instant breasts, leave newborn males infertile, lead to spontaneous thyroid combustion (poof!) and pretty much ensure that a woman will get breast cancer.

From the perspective of someone who reads a LOT of medical literature, I can tell you that research is overwhelmingly positive on the health benefits of soy.  However, these benefits come with a few conditions.

  1. We are talking about unprocessed (NO soy burgers or TVP!!) and non-GMO soy
  2. The most protective compounds are called phytoestrogens.  The most common of these are the isoflavones genistein and daidzein
  3. These isoflavones are converted by health bacterial flora into more powerful compounds called enterolactone (antibiotics may destroy this ability)

So before we can have any discussion about the health effects of soy foods, these 3 items need to be fully understood and taken into consideration.  This means that eating soy dogs and soy burgers cannot be considered healthy because they are processed.

It also means that non-organic and non-GMO soy have concerns due to the genetic modification of the proteins and cannot be considered.

Lastly, even if we do eat more organic, unprocessed soy, it is likely that, due to lifestyles that do not support the growth of good bacteria in our gut, we will not achieve the strongest benefit from intakes of soy.

With these factors considered, what does the research say about soy and breast cancer?

  1. Soy intake as an adolescent cuts future breast cancer risk by 60%
  2. Yet another study showing a 59% lower risk with higher intakes as a teen
  3.  Higher soy intakes led to a 32% lower risk of dying in women with breast cancer

There are more, but this should be more than enough to begin to show you that the research behind soy is solid.

This particular study adds further weight to the evidence.  Researchers found, that, in those with the highest intakes of isoflavones from soy compared to the lowest intakes:

  1. A 13% lower risk of dying overall
  2. A 17% lower risk of dying from breast cancer
  3. A 25% lower risk of breast cancer recurrence

Overall, these are some pretty strong benefits and may even beat the long term use of drugs like Tamoxifen to prevent breast cancer recurrence (although Tamoxifen increases the risk of cancer in the OTHER breast, while soy does not…).

Consider soy intakes as soy milk, edamame, tofu or miso.

Have you avoided soy because of fear of the damage it may do to your health?

James Bogash

For more than a decade, Dr. Bogash has stayed current with the medical literature as it relates to physiology, disease prevention and disease management. He uses his knowledge to educate patients, the community and cyberspace on the best way to avoid and / or manage chronic diseases using lifestyle and targeted supplementation.