Soy: The Inside Scoop

Inside Scoop on Soy: Myths and Truths

Many patients ask me about the consumption of soy, citing “I’ve always heard that it was bad”. However, the truth is much more complex than a simple yes or no. Depending on who you ask, it is either a super-food or a poison. But the truth is, soy-based foods have been shown to improve cholesterol, prevent breast cancer, prostate cancer, decrease osteoporosis and more.  But, yes, it does have some downsides as well. Here’s the breakdown:

1.       Hormone Changes

Soy has a reputation of being “estrogenic” and is often avoided because of this. The truth is not so simple. Soy contains phytoestrogens that are both estrogenic and anti-estrogenic. How can this be? Soy’s phytoestrogens are about one twentieth as strong as your body’s natural estrogen, therefore in low-estrogen conditions (e.g. menopause); the phytoestrogens can weakly stimulate the estrogen receptor. However in high estrogen conditions (e.g. endometriosis), the phytoestrogens can adhere to the estrogen receptor but not stimulate it, blocking your natural estrogen.  

What about in children?
In pre-pubescent children, cow milk has been shown to be more endocrine disrupting that soy milk.

2.       Breast Cancer

Believe it or not, soy has been shown to reduce the rates of breast cancer occurrence. It may actually help prevent the development of breast cancer. But in patients who already have a hormone sensitive cancer, the phytoestrogens may stimulate the cancer cells, so I recommend avoidance for those individuals.

3.       Thyroid Health

Soy is considered goitrogenic, which means that it may interfere with the production of thyroid hormones by altering iodine uptake. While studies show that soy products do not cause hypothyroidism, those who consume more soy may need more iodine in their diets (a great source for iodine is seaweed and other sea veggies)

4.       The Cautions

 “Soy protein isolate” means that the soy has been processed and the nutrients have been stripped away, often replaced with added sugars, fats and refined flours.  Avoid soy burgers, energy bars, and other “Frankensoy” products. Typically, I caution patients when discussing soy milk. Often, soy milk is processed and does not have any nutritional benefit.  

Use Organic Soy. Soy is highly sprayed with pesticides and herbicides, which have been shown to be detrimental to health. Avoid soybean oil, it is mostly filled with pro-inflammatory omega-6 fatty acids.  And eliminate soy if you have an intolerance or allergy to it. 


Like all foods, consume soy in moderation; I recommend 1 serving a couple of times per week, with a helping of sea veggies (or other iodine-rich food). Organic whole soy foods are the best; including tofu, edamame, tempeh, and fermented soy, as they contain more nutritional benefits. 


Posted on August 11, 2016 .