Does Soy Lower Testosterone?

Written by Kate Harrison

Fact Checked by: Roger Thomas


PathMed is reader-supported. Our independent research is completed by trained nutritionalists and a team of well informed writers. Our content is then edited and fact checked by our editorial team. When you make a purchase through our links we may earn a commission.

Many people worry about their testosterone levels. There are very good reasons for this.

Testosterone is a hormone. Though it is found in significantly higher amounts in men than women, everybody needs a healthy amount of it. Not having enough can lead to a great many health and wellbeing problems. A lack can lead to impaired sexual function, decreased energy levels, and atrophy (the wasting of muscles) with an inability to improve athletically, to name just a few concerns.

With this in mind, it’s only natural to worry when it’s widely reported that a certain foodstuff can lower your testosterone levels.

Over the years, soy has taken a lot of flack in this regard. Because of its chemical make up (it contains phytoestrogens, which we will get into below), it is often ascribed feminizing properties. Inhibited testosterone lies under this claim.

But Does Soy Really Lower Testosterone?

green soy beans

The short answer is that no, it doesn’t. Its endocrinal effects are actually quite limited, meaning that it won’t really affect your hormone levels very much at all.

However, the question still hangs over a lot of people’s heads. Many people won’t eat soy products or drink soy protein shakes (which is a shame, as they are fantastic for maintaining healthy muscle mass and a solid micronutrition intake.)

It’s time it was put to bed. Luckily, a recent meta-analysis in Reproductive Toxology (2021) gives us all the answers we could ever want.

Soy and Reproductive Toxology

Firstly, yes, soy contains phytoestrogens in the form of isoflavones. It is, in fact, one of the richest sources of isoflavones money can buy. This has caused a great deal of concern for men’s health in certain circles. It is thought that the consumption of phytoestrogens (basically a plant form of estrogen) raises a persons’ estrogen content and/or output and diminishes their testosterone output.

However, this is far from the case. Data from 38 clinical studies have been thoroughly analyzed to examine effects of soy/isoflavones on hormone levels. This resulted in the (2021) meta-analysis in Reproductive Toxology. 

The Results?

There were no noted effects of soy/isoflavones on testosterone or estrogen levels in men. Phytoestrogens simply don’t seem to alter hormone production.

So what does lower testosterone?

Though soy and phytoestrogen don’t affect testosterone levels, the fear was valid. There are plenty of things that can greatly inhibit testosterone production in men.

For starters, age can lower testosterone levels. It usually will, in fact – a natural decline begins at thirty and continues for the rest of your life, dropping about 1% per year.

Then there are the knocks we get along the way. Injury, trauma, or infection to the testes (orchitis) will generally lower testosterone levels, as will chemotherapy, radiation exposure, and inflammatory conditions such as sarcoidosis. Head trauma can often have a large impact. Obesity and/or extreme weight loss will also often lead to lower testosterone levels, as will type II diabetes.

getting older

Drug and alcohol abuse will also generally lead to lower testosterone levels. Alcohol abuse and anabolic steroid use in sports are particularly prominent in diminishing testosterone levels, often to the point at which medical intervention is required. Cirrhosis of the liver, often caused by excessive alcohol use, can impact testosterone levels, too.

Certain illnesses and medical conditions can also negatively impact testosterone levels. Both acute and chronic conditions can play a part. Pituitary gland dysfunction or tumors, metabolic disorders like hemochromatosis, renal (kidney) failure, HIV/AIDS, Kallman syndrome (in which the hypothalamus, a gland in the brain that controls hormone function, develops abnormally), XXY syndrome, or Klinefelter syndrome (a genetic condition where men are born with an extra copy of the X chromosome), hypothyroidism and sleep apnea all play larger or lesser parts. Chronic stress and depression will also diminish your ability to produce healthy amounts of testosterone.

Certain medications can impair testosterone output, too. These include opioids, certain hormonal treatments, such as those used to treat cancer, and, of course, steroids (like prednisone, commonly used to treat asthma.)

Musculature and physical activity also play a role. This is more complex, as it’s kind of circular. Those with lower testosterone won’t be able to build muscle mass or train as extensively as those with healthy amounts. In turn, people with low muscle mass and those who are sedentary won’t create enough testosterone to remain healthy. However, just as the cause is cyclical, so is the cure – break the cycle, get physically active, build a little muscle, and you’ll find yourself in a virtuous cycle.

How Do You Know If You Have Low Testosterone Levels?

You can speak to your healthcare provider about your concerns. They will be able to run a couple of simple tests to find out how healthy your hormonal output is.

However, there are some common symptoms you can look out for yourself to judge whether or not you’re producing healthy amounts of testosterone. These include low sex drive, poor sexual performance/erectile dysfunction, depression or flattened mood, moodiness and irritability, decreased sense of wellbeing, fatigue, problems with memory and concentration, and a loss of muscular strength and athletic ability. You may also notice heightened levels of body fat and even gynecomastia (breast development).

What Can You Do To Increase Testosterone?

How can you build up your testosterone levels if they are low?

If they are chronically low, medical intervention may be required. This will likely be the case in people who have previously abused anabolic steroids.

There are some simple lifestyle changes you can make, too.

Though there will be little you can do about some of the illnesses and medications listed above, staying on top of many of them and managing your overall health will be a good first step.

Make sure you live an active lifestyle. Specifically, take part in some form of resistance training. Swimming, boxing, yoga, and various forms of weight lifting have been shown to build lean muscle and thus improve testosterone output.

Couple this with plenty of good quality protein (some of which can, maybe even should, come from soy!) and healthy fats to recover fully from exercise and optimize your hormonal output.

Stress can kill your testosterone output faster than anything. Manage your stress levels for a healthier lifestyles. If your job is stressing you out, consider changing direction or slowing down the pace, if you can. Practice calming exercises like yoga, meditation, and deep breathing. Limit your consumption of stimulants – caffeine, guarana, and so on.

Don’t drink too much or too often, and definitely stay away from any harder drugs. Use natural supplementation such as natural testosterone boosters in your training diet – never, ever take anabolic steroids or exogenous testosterone. They will diminish or even destroy your ability to product testosterone. There are plenty of natural compounds, however, that can actively help to normalize production – these include commonly found ingredients like DHEA, vitamin D, magnesium, Tribulus Terrestri and D-aspartic acid.

Follow these techniques for raising your testosterone. Stop worrying about soy. It’s not the culprit, here, and can be actively useful in building a strong, lean, testosterone fueled physique.