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All About Soy

“Is soy bad for you, or is soy good for you?” is a common question I get asked as nutritionist. Unfortunately, the answer is not a simple one, because there is conflicting evidence on this topic. My general answer is that soy is bad for you most of the time, but there are some exceptions when it can be good. In this blog post, you can learn more about soy and when it can be harmful or helpful!


In order to understand soy, it is important to understand phytoestrogens. Phytoestrogens are known as “dietary estrogens” because they are not produced in the body like the estrogen hormone. Instead, they are ingested or consumed through certain foods. Phytoestrogens are found in plants like soy, where they are used as a natural defense against herbivores: they are secreted to affect the fertility of animals that may eat them, in order to reduce further attacks (Hughes, 1988).

When ingested by humans, phytoestrogens can behave in two ways in the body: they either mimic estrogen or act as an estrogen blocker. When they act as estrogen, the resulting excess of estrogen can have negative effects on both women and men. For the majority of young women, extra estrogen in the body can contribute to infertility, PCOS, certain types of cancer, and other hormone imbalance-related disorders (Shu et al., 2009). Men can also be negatively affected by increased estrogen, as it can throw of their hormone balance. Women over the age of 50, however, may benefit from phytoestrogens when they have decreased estrogen levels, which occur during menopause.

Other Foods With Phytoestrogens

  • Tempeh
  • Flaxseeds
  • Oats
  • Barley
  • Lentils
  • Sesame seeds
  • Yams
  • Alfalfa
  • Apples
  • Carrots
  • Pomegranates
  • Wheat germ
  • Coffee
  • Licorice
  • Hops
  • Bourbon
  • Beer
  • Red clover


Soy is the most phytoestrogen-rich food found in the diet. When consuming most soy products, you are consuming a lot of excess estrogen, which can throw off the delicate balance of hormones in the body. It is also important to know that 90 percent of soy today is genetically modified (USDA Economic Research Service, 2017). Genetically modified organisms (or GMOs) are linked to many health problems. They have been shown to kill off good bacteria in your gut, affect the proper functioning of the digestive system, and may have negative effects on other organs (Dona & Arvanitoyannis, 2009).

Soy Products to Avoid

  • ALL GMO soy
  • Soy milk (organic or conventional)
  • Soy protein powders
  • Texturized soy protein (TVP)

What Soy is Healthy?

Soy can be good for you if it is organic and fermented. This way, you can be sure its not GMO soy, and fermentation provides beneficial probiotics to help your body handle the excess estrogen. Another way to make soy products better for you is to pair it with seaweed, as is often done in the Japanese culture, like in miso soup. Seaweed helps your body properly digest the soy.

Soy Products Healthy to Consume in Moderation

  • Natto
  • Organic sprouted tofu
  • Tempeh
  • Miso

Individuals who have cancer and those struggling with infertility, PCOS, or other hormone imbalances should consult with a physician to see if soy is ok to be consumed.

The effects of soy and phytoestrogens are controversial, and research on this topic is conflicting. However, knowing the types of soy that are healthy and unhealthy to consume can help in your decision on whether to eat it or not. Understanding the role of phytoestrogens in your health is a key part to maintaining proper hormone levels throughout your life. To learn more about nutritional health, contact us today!




Dona, A., & Arvanitoyannis, I. S. (2009). Health risks of genetically modified foods. Critical reviews in food science and nutrition, 49(2), 164-175.

Hughes Jr, C. L. (1988). Phytochemical mimicry of reproductive hormones and modulation of herbivore fertility by phytoestrogens. Environmental Health Perspectives, 78, 171.

Shu, X. O., Zheng, Y., Cai, H., Gu, K., Chen, Z., Zheng, W., & Lu, W. (2009). Soy food intake and breast cancer survival. Jama, 302(22), 2437-2443.

United States Department of Agriculture Economic Research Service (2017, July 12). Recent Trends in GE Adoption. Retrieved from https://www.ers.usda.gov/data-products/adoption-of-genetically-engineered-crops-in-the-us/recent-trends-in-ge-adoption.aspx