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Is Soy Milk Bad for Men?
The Side Effects on Testosterone Levels

Jason Hughes
Published by Jason Hughes
Fact checked by Markus Oliver, BHSc FACT CHECKED
Last updated: January 4, 2022

There’s a lot of confusion and scaremongering around soy consumption these days, despite it being so prevalent in many cuisines.

You may have heard that consuming soy can be dangerous for males, giving them fertility issues and problems with their sexual reproductive system.

However, it seems that some experts are not convinced, holding soy up as a healthy vegan protein source which is vital to men’s health when coupled with general healthy eating.

Soya is a complete source of protein which makes it ideal [for] men following a vegetarian or vegan diet. Eating soya also has a positive impact on blood cholesterol levels which helps to reduce the risk of heart disease.


- Nichola Ludlam-Raine, Dietician

What Is Soy?

Soy Bag

Soy comes in many different forms these days, but it all starts with soybeans.

These soybeans can be processed into many different soy products, with some of the most common food products being things like tofu and dietary supplements/vitamins which contain soy.

Many vegan protein products are also made from soy protein, as it is 100% vegan.

“Whole Soy” products are often found in Eastern cuisine, featuring heavily in soy-rich nutrients-dense dishes such as tofu, tempeh, teriyaki, miso, soy sauce, and more. If you’re new to cooking and newer prepared tofu, here's a quick guide on how to press tofu.

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You can also get fermented soy which (you guessed it) has been left to ferment for a while, and this is found in popular East Asian foods such as Natto (1).

Do bear in mind that this legume can be used to make processed foods as well, so it’s not always necessarily a sign of healthy food if something contains soy.

For example, many veggie and vegan-friendly meat substitutes are packed with processed soy.

Health Benefits

1. Prostate Cancer

Soy contains phytoestrogens, and the ones found in soybeans are called soy isoflavones. These compounds are said to reduce prostate cancer risk in males, although more research needs to be done (2).

Still, potentially lowering your cancer risk is great news, as prostate cancer is one of the worst cancers for guys to get. For example, in the UK, 1 in 8 men will get prostate cancer at some point in their lives.

2. Heart Disease

The claim is controversial, but many people reckon that a high intake of soy can help to prevent symptoms of heart disease and lower cholesterol levels in both men and women.

However, the FDA has recently claimed that the evidence for this is weak, so it’s worth being critical about soy’s role in preventing the risk of these problems.

Nonetheless, a lot of scientific research still suggests that a high soy diet can help reduce heart disease risks.

3. Bone Health

Soybeans are noted for their concentration of minerals and vitamins, helping to improve bone health and stave off the symptoms of health conditions such as Osteoporosis.

Put simply, the compounds in soy can help with bone growth and enlargement, ensuring that adults grow healthily as they age.

Adequate soy nutrition in your diet can thus help your bones to stay strong and sturdy.

​Negative Effects For Males

Negative Effects

1. Sexual Libido

Soy consumption in males can lower men's natural estrogen levels. This can have so-called “feminizing effects” which cause guys to lose their appetite for sex (3).

It can also cause some men to have emotional mood swings reminiscent of a hormonal woman, although this effect has little scientific evidence to back it up.

Nonetheless, soy’s possible side effects on men could be off-putting for some.

Related Post: Does Going Vegan Affect Your Sex Drive?

2. Fertility

Some studies have suggested that excessive soy consumption could lead to decreased fertility in men.

Again, there is more research needed in order to confirm this, but 1 study found that men on a high soy diet had 32% fewer sperm per millimeter of ejaculate when compared to men who would avoid soy products.

These supposed changes to guys’ testosterone levels and fertility have been enough to see many men avoid soy in their diet.

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3. Dementia

Some studies have suggested that intake of tofu (a soy product) is linked to an earlier onset of dementia in both men and women, although there are multiple studies that contest this, so it’s definitely worth taking with a pinch of salt.

Does Soy Affect My Testosterone Levels?

Soy does not affect your testosterone levels.

Soy contains phytoestrogens, the sex hormones which are most commonly associated with women. However, consuming more estrogen will not cause men’s testosterone levels to diminish. Men naturally produce both testosterone and estrogen in the body, despite their different roles.

But if you do find yourself to be low on testosterone levels, here are some good t-boosting options:

You can also read about testosterone levels on a vegan diet. Additionally, you can watch this soy-testosterone explanation from Youtuber PictureFit.

​Related Post: Best Vegan Condom Brands


What Daily Soy Intake Is Safe for My Health?

A daily soy intake of 70g of soy protein or 240mg of soy isoflavones per day is safe for your health according to various sources. Many of the longest-living countries in the world have diets high in soy, including nations like Japan where life expectancy is currently 84 years (4).

Can Soy Consumption Lead to Heart Disease?

Soy consumption does not lead to heart disease. In fact, research suggests that consuming soy foods could actually reduce the risk of heart problems. This is because soy can help to lower your cholesterol levels, an essential step to keeping your heart healthy.

Does Soy Increase Estrogen in Males?

Soy can slightly increase estrogen levels in males, although the “feminizing effects” of this are said to be minimal or non-existent. In fact, if consumed in appropriate amounts, soy’s estrogenic effects can positively affect your bones, brain, and cardiovascular system.

​Is Soy Bad For Men? The Bottom Line

Man drinking soy milk

Soy protein is one of the cornerstones of a vegan diet, so it makes sense that vegan men may be worried about their diet and nutrition if they eat a lot of soy.

Allow me to put your mind at rest – unless you have a soy allergy or you neglect your health and fitness, then consuming soy is fine if you’re a man. 

You won’t grow breasts or wake up and find that your penis has fallen off, so chill out.

Eating soy could actually help to improve heart health, bone health, and reduce the risk of prostate cancer, which is a fatal cancer for so many men.

If anything, you should probably be praising soy protein’s good (vegan) name and wolfing down soy protein powder like it’s going out of fashion.

You can read our full guide here: OUR TOP RECOMMENDED PROTEIN POWDERS

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  1. Why Natto Is Super Healthy and Nutritious. (n.d.). Retrieved from https://www.healthline.com/nutrition/natto
  2. Aacr. (2007, March 15). Soy found protective against localized prostate cancer. Retrieved from https://www.eurekalert.org/pub_releases/2007-03/aafc-sfp031507.php
  3. Villines, Z. (n.d.). Anti-estrogen diet for men: What to eat and avoid. Retrieved from https://www.medicalnewstoday.com/articles/323224.php
  4. Pitofsky, M. (2018, August 05). What countries have the longest life expectancies? Retrieved from https://www.usatoday.com/story/news/2018/07/27/life-expectancies-2018-japan-switzerland-spain/848675002/

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1 thought on “Is Soy Milk Bad for Men?
The Side Effects on Testosterone Levels

  1. Whate about eating more than 100g of protein from tofu? On cutting i eate lot of tofu. Is the content of soy (tofu) protein irrelevant?

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