Does Soy decrease testosterone in men?

Did you know? Testosterone plays a crucial role in the overall well-being of men.

It affects various aspects of your life such as sex drive, muscle mass, and body weight.

When your testosterone levels are low, it can lead to health issues that worsen with age, potentially causing illness and other complications. 

Maintaining healthy testosterone levels is essential for men's health throughout their lives. 

But where does soy fit in? And does consuming it really decrease testosterone levels? 

Or has this popular food simply received a bad rap? 

Let's take a look at the relationship between soy and testosterone levels, breaking down any myths, exposing the truths and giving you all the scientifically backed information you need to take on your t-levels once and for all.

What is soy?

Soy is a nutrient-dense legume that’s a popular choice for vegans and those who eat meat alternatives. It has been used in Asia for millennia as a food source.

Soybeans are very rich in protein with ‘soy protein’ products lining the shelves in just about every supermarket. These products include soy milk, tofu, tempeh, and protein powders as some of the main choices.

According to Harvard University's T.H. Chan School of Public Health, soy can be consumed several times a week and is likely to provide health benefits when eaten as an alternative to red and processed meat.

Soy and Essential Amino Acids

Soy is a rich source of essential amino acids, which are organic compounds that are vital when it comes to the power function of our bodies. 

Amino acids are often thought of as the ‘building blocks of protein’ and play a very important role in many bodily functions like hormone synthesis, neurotransmitter production, and muscle growth and repair.

Essential amino acids are amino acids not produced by the human body alone, so we get them from our diet.

When you break down the nine essential amino acids, they are:

• Histidine
• Isoleucine
• Leucine
• Lysine
• Methionine
• Phenylalanine
• Threonine
• Tryptophan
• Valine

The combination of these amino acids are necessary for the synthesis of proteins and the maintenance of overall health in men and women.

Fermented soy foods are a brilliant go-to for protein as they provide all the essential amino acids the human body needs. 

What are the components found in soy?

Part of the reason why soy is both celebrated and criticised is its high concentration of isoflavones which are a type of plant oestrogen (phytoestrogen).

These phytoestrogens are similar in their function to human oestrogen, but far less powerful and are estrogenic or anti-estrogenic. Estrogenic compounds mimic the effects of oestrogen. Anti-estrogens counteract the effects of oestrogen.

Oestrogen is a hormone that plays a key role in the development and functioning of the female reproductive system. This is where the rumour comes from, that the consumption of too much soy in men results in too much oestrogen and leads to ‘man boobs’ (a.k.a. moobs) , a flood of female hormones, and more.

What food is soy in?

In its unprocessed form, soy can be found in whole soybeans and edamame beans which are young soybeans, still in their pods.

Soy can also be found in many other foods like tofu, soy sauce, soy milk, soy flour, and soy meat alternatives. Additional alternatives commonly consumed by health-conscious men are soy bacon, ice-cream, and cheese as well as breaded food, dairy substitutes, cereals and various other processed foods.

You may not think you are eating soy on a daily basis but it appears in many baked goods as soy flour, in particular cookies as a binder and protein enhancer as well as condiments like barbecue sauce and salad dressings. 

Did you know? It’s common to find soy lecithin, a fatty substance found in soy oil in things like whey protein powder as it is great as an emulsifier.  

Why is Soy in So Many Foods?

It basically comes down to its affordability and versatility.

• It’s easily processed into different forms like soybean oil, soy flour, and soy protein isolate, making it used in many different types of food products
• Soy raises the nutritional profile of foods it is incorporated into due to its health benefits, such as being low in saturated fat and cholesterol
• Soy-based ingredients have textural properties that aid in the binding, moisturising and emulsifying of foods.

How much soy should I eat?

Naturally, how much soy you eat depends on your health goals and dietary needs. Vegans will typically consume more than non-vegans, for example.

However, there isn't actually a recommended daily intake of soy established by authoritative bodies.

Really. it's down to your age, dietary preferences and health status. 

FYI: The latest 202-2025 Dietary Guidelines 2020-2025 Dietary Guidelines mention consuming at least 25 grams of soy protein per day to potentially benefit from its health effects. 

This is roughly equivalent to one to two servings of soy foods.

For example, one serving of soy can include:

• One cup (240 ml) of soy milk

• 100 grams of tofu

• Half a cup (90 grams) of cooked soybeans (edamame)

• Two to three ounces (55-85 grams) of tempeh

The U.S. Soybean Export Council suggests that consuming at least 50 grams of soyfoods per day is a step towards meeting your nutrient needs.

In terms of how much soy is too much soy, the upper limit isn’t fully established.

NutritionFacts.org suggests that consuming seven to 18 servings of soy a day may potentially neutralise some of the benefits of avoiding animal protein. But, it’s worth noting that excessive consumption may result in imbalances. 

How does soy impact testosterone levels?

Is there a direct link between soy and testosterone levels in men? 

Does it increase t-levels, decrease them or have no effect?

Let's take a quick look first at what low t-levels look like.

What are the symptoms of low testosterone?

Common symptoms of low t-levels are: 

• Fatigue: Reduced energy and feeling tired are frequently reported symptoms.
• Low sex drive: Libido can suffer from low T levels and a decline in sex drive.
• Increased body fat: Particularly around the waist, men may experience an increase in body fat.
• Erectile dysfunction: As t-levels play an important role in sexual function, men with low levels may struggle to get or maintain erections.
• Reduced muscle mass: Testosterone is vital for maintaining and building muscle mass; lower levels result in a loss of lean muscle mass.

NOTE: If you’re experiencing any of these symptoms, check in with your healthcare provider to check your levels and rule out other conditions.

Soy and testosterone levels

Let’s take a look at the clinical studies that have shown links between soy and testosterone in men - both good and bad.

There are several clinical studies that have explored the potential estrogenic effects of soy. One study published in ScienceDirect raises concerns about phytoestrogens in soy potentially feminising men. It describes the feminising effects, such as higher oestrogen levels in men and lower testosterone levels.

One study found that consuming soy protein powder for 28 days led to a 19% decrease in testosterone levels in male participants.

Another study reported a decrease in testosterone and dihydrotestosterone (DHT) with an increase in estradiol levels after consuming soy protein isolate over a 57-day period.

While this may be the case, a review published in Pubmed found that neither soy nor isoflavone intake had significant effects on male reproductive hormones, including testosterone levels. 

A study in favour of soy having no effect on testosterone suggests that soy does not have a significant impact on testosterone levels in men, regardless of age.

It seems the effects of soy on testosterone aren’t truly known. So, speaking frankly, there aren’t any definitive opinions on the subject.

But one thing’s for sure, the negative effects of soy on testosterone levels have not been confirmed by conclusive research and further studies are needed to fully understand soy's impact on male hormones.

It’s worth considering that the effects of soy on testosterone levels in men may also vary, particularly when it comes to overall diet and genetic predisposition.  

Sex hormone-binding globulin and soy

Sex Hormone Binding Globulin (SHBG) is a protein produced mainly in the liver. It plays a main role in regulating the effects of sex hormones like oestrogen and testosterone. SHBG binds these hormones and can decrease their bioavailability and activity.

While there’s limited research exploring the specific relationship between SHBG levels and soy, there are some studies examining the effects of soy isoflavones on SHBG levels.

A study conducted on Japanese men found an inverse association between soy product intake and SHBG levels. But, it’s worth noting that this study was in a questionnaire format which may have limitations in accurately assessing soy intake. 

Are there any health benefits of soy?

As we know, soy is packed with protein and essential amino acids, but there are many more health benefits packed in there too.

Vitamin and mineral-dense

These are the vitamins and minerals soy provides:

• Copper: This trace mineral helps produce haemoglobin and red blood cells.
• Folate: Also known as Vitamin B9, folate is important for the production of new cells, cell growth and DNA repair. 
• Molybdenum: This trace mineral assists in breaking down certain amino acids. 
• Phosphorus: This essential mineral helps to support bone density, regulate membrane function and control gene expression. 
• Vitamin K1: Important for the prevention of heart disease, blood clotting and bone health. 
• Thiamine: Also known as Vitamin B1, it helps to break down carbs and is required for nerve function. 

Lowers cholesterol levels

Soy has the unique ability to help lower cholesterol levels, especially low-density lipoprotein (LDL) cholesterol, also known as ‘bad’ cholesterol.

The isoflavones in soy-based foods have cholesterol-lowering effects.

Did you know? Research also shows that consuming soy protein can even decrease LDL cholesterol by around 3%, which is great news if you need to lower your levels.

Further studies indicate soy can influence cholesterol metabolism by increasing the production of high-density lipoprotein (HDL) cholesterol, commonly referred to as ‘good’ cholesterol.

Protects your heart

Due to being packed full of polyunsaturated fats, vitamins, minerals and fibre, soy is a great food source for heart health.

Soy isoflavones also play a role in protecting the heart. Studies have shown that soy isoflavones contain anti-inflammatory properties.

As chronic inflammation is associated with the development and progression of cardiovascular disease, soy isoflavones may help reduce the inflammatory response thus preventing and managing heart disease.

Soybeans themselves contain antioxidants that minimise the damage caused by molecules called free radicals. 

These free radicals are responsible for chronic diseases such as heart disease and ageing. The polyphenols found in soybeans help to protect our bodies against cell damage.

Its antioxidant properties act to reduce oxidative stress, protecting the heart from damage. 

Lowers blood pressure

Soy may also help to lower blood pressure due to the high arginine content it contains, which is said to have antihypertensive effects.

Arginine is important because it helps produce a molecule called nitric oxide, which can relax and widen blood vessels. When blood vessels are relaxed and widened, blood can flow more easily, and this can ultimately lead to lower blood pressure. 

There may also be a link between soy and blood pressure regulation due to gut microbiota.

Helps manage weight

Weaving soy protein into a balanced diet may help with weight management. Protein has been shown to reduce appetite and increase satiety which results in less calories consumed.

Exercise recovery and muscle synthesis

Eating a good dose of soy protein after exercise can help support muscle synthesis post-workout and aid recovery times too. Plant-based athletes do this for the ultimate bounce-back.

Prevents prostate cancer

The findings on this subject are not definitive, and the scientific community shares varying viewpoints.

Some studies suggest that soy consumption may be associated with a reduced risk of prostate cancer. 

As we know, soy contains bioactive compounds called isoflavones, which have anti-cancer properties and may even prevent the growth of cancer cells.

Consuming soy has been linked to a lower risk of aggressive prostate cancer and reduced prostate-specific antigen (PSA) levels, the markers of prostate cancer progression.

Obviously, this is huge if it is true. And, considering prostate cancer is most common from 70 years onwards, getting on the right path early could help for the future.

Prevents breast cancer

The relationship between soy and breast cancer has been the subject of a bunch of research and discussion.

Similarly to prostate cancer, soy has been linked to having a protective effect against breast cancer.

Again, it’s due to those isoflavones that bind to oestrogen receptors in the body and reduce the binding of stronger natural estrogens, which promote the growth of some breast cancers.

High soy intake was associated with a reduced risk of breast cancer, particularly in Asia where soy consumption is highest.

Of course, more research must be conducted to fully understand the mechanisms involved. 

What soy products are best to eat?

If you’re planning on including soy in your diet, try to eat normal amounts of whole foods and fermented foods. Ideally, minimally processed soy foods are best.

• Tofu is a great source of protein, iron and calcium. Tofu is a good source of protein, calcium, and iron

• Tempeh is a really good source of fibre, vitamins, minerals and protein

• Miso, the traditional fermented soybean paste, provides protein, vitamins, and minerals, as well as beneficial probiotics

Can I have soy protein powders?

Considering soy protein is frequently used in the food industry in powders, supplements and the like, it is safe to say that yes—you can have soy protein powders even if your t-levels are low.

The science behind the link between hormonal changes in men and the effects of soy protein is inconclusive, but soy is high in many minerals, vitamins, and protein and is highly digestible, which are pluses for an overall healthy diet.

Should men drink soy milk?

Due to all the health benefits of soy, a moderate soy milk intake for men is very unlikely to affect their hormonal health.

All in all, it's a great option for men who want to reduce or avoid dairy intake.

Is soy Sauce bad for males?

No, soy sauce itself isn’t inherently bad for males (or women).

It’s a fermented condiment with many health benefits, but it does contain a large amount of salt, so those with high blood pressure should watch out. 

Foods to Boost T-levels 

Let’s talk about the foods to avoid and the ones to target to help boost your T-levels.

What foods should I avoid?

By taking control of your diet, you can help to maintain or even improve your t-levels. That means eliminating certain foods and cutting down others. 

These are the foods and drinks to avoid or cut back on for optimal hormone balance.

• Research has shown that spearmint and peppermint might negatively affect t-levels. If you drink a large amount of peppermint tea or mint tea it may be worth cutting down

• Licorice root in large amounts has been linked to a potential decrease in t-levels, so steer clear of this

• Alcohol is worth cutting down on or cutting out anyway, but alcohol consumption does have a link to lower testosterone levels. 

Which supplements might decrease testosterone levels?

If you’re taking supplements, it’s great that you’re pushing for optimal health and you’re taking it seriously.

But read this before you continue with your regular doses—especially if you have low t-levels, as you may be unknowingly affecting them.

Some supplements are linked to lowering testosterone levels. These include:

• Zinc: We‘re talking excessive amounts over a long period of time for this to have a negative impact on t-levels, but it is possible.
• Vitamin D: Excessive use can have the undesired effect of potentially decreasing t-levels.
• Omega-3 Fish Oil: In high doses, it has a mildly suppressing effect on testosterone levels.
• Flaxseed: There’s only limited research on this, but some studies suggest that ingesting too many compounds called lignans found in flaxseeds can have oestrogen-like effects on the body.

Basically, any supplement or food you have in higher than recommended doses isn’t a good idea and may have detrimental effects on your health. 

Stick to recommended dosages and never exceed them.

What other foods are good for testosterone levels?

These are the best foods to include in your diet to target your T-levels.

• Shellfish: Particularly oysters. These are high in zinc which plays a lead role in testosterone production.
• Onions and garlic: Rich in antioxidants, these two foods help reduce inflammation and potentially support maintaining healthy t-levels.
• Leafy green veg: This type of veg is brimming with magnesium and vitamin D, which may help increase levels.
• Fatty Fish: Omega-3 helps support healthy t-levels, so fish like sardines, trout, and salmon are recommended to consume.
• Ginger: While more research is needed, there have been some links between ginger and its positive effect on t-levels.
• Cocoa: The flavonoids found in dark chocolate have the potential to boost testosterone levels.

Should you include soy in your diet if you are boosting t-levels?

It's important to know that some studies that link soy consumption to negative effects on testosterone levels are pretty much down to the individuals studied consuming very high amounts of soy products outside of standard daily needs.

One thing that isn’t debated is the high nutritional value of soy and how the recommended amount of it daily will bring multiple benefits to your health.

So, is soy good for your overall health? Yes.

If you are trying to boost your T-levels, should you include soy in your diet? Not necessarily. 

There are other things you can eat and lifestyle changes you can make to help target your T-levels.

What other factors influence testosterone levels?

Maintaining and increasing t-levels isn’t just down to diet.

Take into account these key factors, and you’re even closer to taking back control.

Weight management 

It’s really important to maintain a healthy weight as there is a strong link between obesity and lower testosterone levels. 

Exercise and being physically active

Taking part in regular physical activity and exercising is key in helping to boost your T-levels. Mixing both resistance training and cardio is best.

Sleep

Getting good, regular sleep is crucial for hormone regulation and supporting healthy t-levels.

Medications and medical conditions

Unfortunately, certain medications that help to manage conditions like chronic liver or kidney disease and diabetes can also influence testosterone levels. Definitely check with your healthcare provider if you are feeling any symptoms of low levels.

Environmental factors

Certain chemicals like pesticides can get in the way of normal hormone production. Keep a keen eye on this if you think you’re regularly exposed to these kinds of chemicals.

Managing stress

It’s easy to lose touch with how stress feels and how damaging it is to your health when we lead such busy and demanding lives. 

However stress and cortisol can negatively impact testosterone levels.

Finding ways to lower your stress, like exercising, mindfulness, meditation and relaxation exercises such as deep breathing, can really help you feel level and calm. 

Which supplements will help my testosterone levels?

For an all-natural Testosterone support that comes with zero side effects, TestoPrime capsules are a great option.

Boost your t-levels with TestoPrime

A daily dose of TestoPrime will target weight loss, help you manage stress, up your endurance, and more. 

Just four capsules a day will help you maintain healthy t-levels. It's a simple and swift way to up your t-levels and get back to where you need to be.