Soy: Good or Bad? Discover the Pros and Cons

by | Feb 28, 2023 | lifestyle-en | 0 comments

Soy: Good or Bad? Discover the Pros & Cons.

Soy is a food that sparks many debates about its effects on health. Despite this, some people continue to avoid consuming it, while not hesitating to eat processed meat, classified as a Group 1 carcinogen in humans.

Looking back on the history of soy in brief…

Soy was first domesticated in China around 3000 to 4000 years ago, in the 11th century BCE.

Although this bean has been cultivated for a long time in Asia, it only appeared in the United States in the 18th century, just 200 years ago.

Initially, soy was introduced to the United States mainly as a forage crop for livestock. However, over time, it became an important crop for human consumption as well.

Today, soy is grown in many countries around the world, including the United States, Brazil, Argentina, and China. It is used to produce a variety of products, such as soy milk, tofu, tempeh, soy protein, and many more.

Due to its nutritional benefits and versatility, soy is becoming increasingly popular worldwide. However, as mentioned earlier, it remains a topic of debate regarding its effects on health.

Let’s examine the main concern regarding soy: phytoestrogens

Soy has often been criticized for its isoflavone content, a type of phytoestrogen derived from the plant (from the Greek “Φυτό” meaning “plant”).

Phytoestrogens act like estrogens and high levels can have both beneficial and harmful effects on health. However, phytoestrogens have both pro and anti-estrogenic effects, meaning they can help maintain healthy estrogen levels, for example by strengthening bones, while reducing the risk of developing breast tumors.

It’s important to note that women need estrogens for their reproductive health, but men also need certain amounts of estrone and estradiol, the two types of estrogens present in men.

Is soy beneficial for women but harmful for men?

Studies suggest that consumption of isoflavones and soy by women is associated with several benefits, including:

  • A moderately reduced risk of coronary heart disease
  • A reduced risk of breast cancer and recurrence, colorectal cancer, endometrial cancer, and bladder cancer
  • Relief from menopause-related symptoms
  • Reduced bone loss in the spine
  • Relief from depressive symptoms during pregnancy

Regarding men, neither soy protein nor exposure to isoflavones have a significant impact on testosterone (TT), free testosterone (FT), estradiol (E2), or estrone (E1) levels.

Another common concern is that soy is genetically modified (primarily in the United States), meaning it has undergone artificial genetic modifications.

Most of the soybean grown in the United States is genetically modified (GM) and used as animal feed, to produce soybean oil, and as an ingredient in processed foods. Therefore, there is a greater likelihood of consuming GM soy by choosing meat, soybean oil, and processed foods rather than whole soy or soy-based products such as soy milk, tofu, tempeh, and soy yogurt.

However, foods bearing the “Organic” label must be free of GM ingredients. By opting for organic products such as organic tofu, the chances of consuming GM soy are therefore close to zero.

It is worth noting that some GM plants have been designed to enhance their nutritional value. For example, GM soybean containing healthier oils can replace oils containing trans fatty acids. After more than 20 years of monitoring by researchers worldwide, many concerns regarding the effects of GM foods on health have been studied and tested. The results have shown that GM foods do not present specific toxicity to human health compared to non-GM foods.

Ultimately, the decision to consume GM foods or not depends on personal preferences and ethical beliefs. It is important to make informed choices by reading labels and doing research to understand the pros and cons of GM foods. Organic products can be helpful in avoiding GM ingredients, but this does not guarantee superior quality or nutritional benefits compared to non-GM foods.

Who should avoid soy?

Now that I’ve discussed all the wonderful benefits of eating soy (while always choosing whole/minimally processed soy types such as unsweetened soy milk, soy yogurt, plain tofu, tempeh, miso, natto, and whole soybeans!).

Let’s talk about the small percentage of the population who should be careful or completely avoid soy:

  • Those who are allergic to soy: There is less than a 0.5% chance that you are allergic to soy. In this case, as with any allergy, it is advised to completely avoid the ingredient that causes the reaction as well as traces of said ingredient.
  • Those who suffer from hypothyroidism: If you are using synthetic thyroid hormone, avoid consuming soy during the hours surrounding the time you take the medication as it can negatively interfere. However, there is no data suggesting that you should completely avoid soy. As always, discuss it with your doctor.
  • Those who have an iodine deficiency: Iodine deficiency increases the anti-thyroid effects of soy, while iodine supplementation is protective, so keep your iodine in check by consuming iodine-rich foods or a supplement. 

Finally and most importantly, soy is extremely nutritious! Making soy a part of your diet (unless you belong to one of the three categories I mentioned above) is a no-brainer for me! It is the bean that contains the most iron, calcium, and protein. They are a complete protein, meaning they contain all 9 essential amino acids. And for us vegans, soy milk or tofu enriched with calcium are excellent sources of dietary calcium, which many vegans lack in their diet.

Did you know?

Traditional Asian diets are the best ways to benefit from the health benefits of soy. These cultures are generally healthier and live longer than Americans. The people of Okinawa, Japan, who have the longest life expectancy in the world, consume on average one to two servings of soy per day, including tofu, soy milk, edamame, and fermented versions such as tamari and miso. Doctors and nutritionists who advocate for a vegan lifestyle recommend these natural soy-based foods that have nourished entire civilizations for centuries, rather than processed soy products such as soy protein isolates, soy protein concentrates, hydrolyzed soy proteins, partially hydrogenated soybean oil, etc.


Hamilton-Reeves,Ph.D. Jill M. et al. “Clinical studies show no effects of soy protein or isoflavones on reproductive hormones in men: results of a meta-analysis.” American Society for Reproductive Medicine.

August 2010. Volume 94, Issue 3, Pages 997–1007. Web. Accessed Nov. 2018.

Celec Ph.D, M.D., Peter. Et al. Increased one week soybean consumption affects spatialabilities but not sex hormone status in men. International Journal of Food Sciences and Nutrition.

Volume 58, 2007 – Issue 6. Pgs 424-428. Web. Accessed Nov. 2018.

Kimura, Tomomi. “East meets West: ethnic differences in prostate cancer epidemiology

between East Asians and Caucasians.” Chinese Journal of Medicine. 2012 Sep, 31(9):

421–429. PMC. Web. Accessed Nov. 2018.

Dupont, Veronica. “GMO corn, soybeans dominate US market.” June 2013. Web.

Accessed Nov. 2018.

Martin-Orue, Susana M., et al. “Degradation of transgenic DNA from genetically modified soya

and maize in human intestinal simulations.” British Journal of Nutrition. June 2002 , Vol 87.

Issue 6. pp. 533-542. Cambridge University Press. Web. Accessed Nov. 2018.

7114502001149 Messina MPH, RD., Ginny. “Soyfoods in Asia: How Much Do People Really Eat?” The Vegan RD. March 2011. Web. Accessed Nov. 2018.

Written by Marieeveco

Passionate about the fine pleasures of health and plant-based nutrition, I explore the most prestigious horizons of nature, oceans, and dream landscapes. My blog is a true gem, designed to help you discover the subtleties of health and wellness, and to inspire you to live your life with refinement and elegance.

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