Testosterone is a sex hormone that plays a powerful role in health.

Maintaining healthy levels of testosterone is important for gaining muscle mass, improving sexual function, and boosting strength (1).

Not to mention, alterations in testosterone levels have been associated with a number of health conditions, including obesity, type 2 diabetes, metabolic syndrome, and heart problems (2).

While many factors are involved in the regulation of testosterone, a healthy diet is key to keeping its levels in check and preventing them from dropping too low.

Here are 8 foods that lower testosterone levels you may want to watch out for.

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Some research shows that regularly eating soy products like edamame, tofu, soy milk, and miso may cause a drop in testosterone levels.

For example, one study in 35 men found that drinking soy protein isolate for 54 days resulted in decreased testosterone levels (3).

Soy foods are also high in phytoestrogens, which are plant-based substances that mimic the effects of estrogen in your body by altering hormone levels and potentially reducing testosterone (4).

Though human-based research is limited, one rat study showed that consuming phytoestrogens significantly decreased testosterone levels and prostate weight (5).

However, other research found conflicting results, suggesting that soy-based foods may not have as much of an effect as these isolated soy components.

In fact, one large review of 15 studies found that soy foods had no effect on testosterone levels in men (6).

Further research is needed to understand how soy products as a whole may influence testosterone levels in humans.

Perhaps most well known for its powerful stomach-soothing properties, some research suggests that mint could cause a dip in testosterone levels.

In particular, spearmint and peppermint — two herbs that hail from the mint family of plants — have been shown to directly affect testosterone.

One 30-day study in 42 women showed that drinking spearmint herbal tea daily caused a significant decline in testosterone levels (7).

Similarly, an animal study found that administering spearmint essential oil to rats for 20 days resulted in reduced testosterone levels (8).

What’s more, another animal study noted that drinking peppermint tea altered hormone levels in rats, leading to a decrease in testosterone, compared with a control group (9).

However, most research on mint and testosterone focuses on women or animals.

High quality human studies focusing on both genders are needed to assess how mint affects testosterone levels in both men and women.

Licorice root is an ingredient commonly used to sweeten candies and beverages.

It’s also a popular natural remedy in holistic medicine and often used to treat everything from chronic pain to persistent coughing (10).

In recent years, several studies have found that licorice may also influence hormone levels, potentially leading to a decline in testosterone over time.

In one study, 25 men consumed 7 grams of licorice root daily, which caused a 26% drop in testosterone levels after just 1 week (11).

Another small study showed that licorice may reduce testosterone levels in women as well, reporting that 3.5 grams of licorice daily decreased testosterone levels by 32% after just one menstrual cycle (12).

Keep in mind that this applies to licorice root rather than licorice candy, which often doesn’t contain any licorice root.

Many of the most common vegetable oils, including canola, soybean, corn, and cottonseed oil, are loaded with polyunsaturated fatty acids.

These fatty acids are usually classified as a healthy source of dietary fat, but they may also decrease testosterone levels, as several studies have suggested.

One study in 69 men showed that frequently consuming polyunsaturated fats was associated with significantly lower testosterone levels (13).

Another study in 12 men looked at the effects of diet on testosterone levels after exercise and reported that polyunsaturated fat intake was linked to lower levels of testosterone (14).

However, recent research is limited, and most studies were observational and had a small sample size.

More high quality studies are needed to examine the effects of vegetable oils on testosterone levels in the general population.

Flaxseed is packed with heart-healthy fats, fiber, and various important vitamins and minerals.

In addition, some research shows that it may cause a decrease in testosterone levels in certain populations.

This is because flaxseed is high in lignans, which are plant compounds that bind to testosterone and force it to be excreted from your body (15, 16).

What’s more, flaxseed is rich in omega-3 fatty acids, which may be linked to a decrease in testosterone as well (17).

In one small study in 25 men with prostate cancer, supplementing with flaxseed and decreasing overall fat intake was shown to significantly reduce testosterone levels (18).

Similarly, a case study reported daily flaxseed supplements decreased testosterone levels in a 31-year-old woman with polycystic ovary syndrome, a condition characterized by increased male hormones (16).

However, more large-scale studies are needed to further evaluate the effects of flaxseed on testosterone levels.

Besides often being high in sodium, calories, and added sugar, processed foods like convenience meals, frozen foods, and prepackaged snacks are also a common source of trans fats.

Trans fats — an unhealthy type of fat — have been linked to an increased risk of heart disease, type 2 diabetes, and inflammation (19, 20, 21).

Plus, some studies have found that regularly consuming trans fats from sources like processed foods could decrease testosterone levels.

For example, one study in 209 men showed that those who consumed the highest amounts of trans fats had 15% lower levels of testosterone than those with the lowest intake.

Additionally, they also had a 37% lower sperm count and a decrease in testicular volume, which may be linked to reduced testicular function (22, 23).

Animal studies have also found that a high intake of trans fats could lower testosterone levels and even impair reproductive performance (24, 25).

While enjoying the occasional glass of wine with dinner has been linked to health benefits, studies show that excessive alcohol intake could cause testosterone levels to plummet, especially in men (26).

A study in 19 healthy adults showed that consuming 30–40 grams of alcohol per day, which equates to about 2–3 standard drinks, decreased testosterone levels in men by 6.8% over 3 weeks (27).

Another study reported that acute alcohol intoxication was associated with increased testosterone in women but decreased levels in men (28).

However, the evidence isn’t completely clear-cut when it comes to the effects of alcohol on testosterone.

In fact, both human and animal studies have had mixed results, with some research indicating that alcohol could actually increase testosterone levels in certain cases (29, 30).

Further research is needed to understand how different doses of alcohol affect testosterone levels in the general population.

Nuts are a great source of many important nutrients, including fiber, heart-healthy fats, and minerals like folic acid, selenium, and magnesium (31).

Additionally, some studies suggest that certain types of nuts may decrease testosterone levels.

One small study in 31 women with polycystic ovary syndrome showed that walnuts and almonds increased levels of sex hormone-binding globulin (SHBG) by 12.5% and 16%, respectively (32).

SHBG is a type of protein that binds to testosterone, which can lead to a decrease in the levels of free testosterone in your body (33).

Nuts are also generally high in polyunsaturated fatty acids, which have been associated with decreased testosterone levels in some studies (13, 14).

Despite these findings, more research is needed to determine how certain types of nuts may affect testosterone levels.

Changing up your diet is one of the most effective ways to maintaining healthy testosterone levels.

If you’re concerned about low testosterone levels, swapping out these testosterone-lowering foods and replacing them with healthy, whole food alternatives can keep levels in check and enhance your overall health.

Additionally, maintaining a healthy lifestyle, getting plenty of sleep, and fitting exercise into your routine are some other significant steps you can take to naturally boost testosterone.