Written by Chelsea DeColle, CNP

When it comes to the topic of soy and hormones, it can be a confusing one to navigate with some much conflicting information out there. There is research on both sides of the fence showing both benefits and negative effects. So, how do you know if soy is right for you and how much to consume?

First, it’s important to understand what soy is: a plant-based source of complete protein. Aside from being a source of protein, soy also contains large amounts of isoflavones, a phytoestrogen (plant form of estrogen).³Isoflavones mimicthe effects of estrogen in the body and can either inhibit or activate the estrogen receptors in the body.⁴ So, isoflavones can have either a positive or potentially negative effect on the body, dependent on a number of factors including your health history, ethnicity, age and quality of soy consumed.³

There is a growing amount of research on soy, with conflicting information on how it may affect different health conditions and people of different ages. Research is emerging that shows a link to certain gut microbial environments that impact the body’s ability to convert soy into equol, a stronger isoflavone.^1,2 Only 30-50% of the world’s population have the ability to properly metabolize soy isoflavones into equol, so not every individual will have the same benefits or effects of consuming soy.^1,2 More research needs to be done to understand this further.

As soy consumption has increased in popularity, especially in the North America, production has also increased resulting in a large amount of the soy produced being genetically modified, heavily sprayed with pesticides, and processed, which reduces the health benefits it may contain and poses additional health risks.³

When considering to consume soy as a part of your diet:

1. Talk to a health care practitioner/nutritionist if you have pre-existing conditions prior to consumption of soy on a regular basis
2. Consider age and impact soy may have based on age
3. Limit consumption to once or twice per week
4. Consume good quality sources that are organic, non-GMO and fermented: 
   • Tempeh
   • Natto
   • Miso
   • Tamari
   • Soy sauce
5. Avoid all processed soy products

References:

1. Yuan JP, Wang JH, Liu X.(2007) Metabolism of dietary soy isoflavones to equol by human intestinal microflora–implications for health. Molecular nutrition & food research, 51(7):765-81.
2. Setchell KD, Brown NM, Lydeking-Olsen E. (2002) The clinical importance of the metabolite equol—a clue to the effectiveness of soy and its isoflavones. The Journal of nutrition, 132(12):3577-84.
3. Harvard T.H. Chan School of Public Health. Straight talk about soy. Accessed on Oct 16, 2020 at:https://www.hsph.harvard.edu/nutritionsource/soy/#:~:text=Soy%20is%20unique%20in%20that,estrogenic%20or%20anti%2Destrogenic%20activity
4. Hwang, C.S., et al. Isoflavone metabolites and their in vitrodual functions: They can act as an estrogenic agonist or antagonist depending on the estrogen concentration. Journal of Steroid Biochemistry and Molecular BiologyVol 101(4-5):246-253.