7 Foods that Can Lower Testosterone Levels Quite Significantly in Men
Just like there are many foodstuffs which can increase testosterone levels, there are also many foods that lower testosterone in men.
In this article, we’re looking at 7 possible foods and/or food groups that can have a negative effect on your androgen levels.
Without further ramblings, let’s check out the seven dietary foods that lower testosterone:
1. Flaxseed Products
Flaxseed products are incredibly popular at the moment, and this is due to their high omega-3 fatty-acid content, which in itself, can be ruled as a positive benefit of flax consumption.
However, when it comes to flaxseed products, I believe that the negative effects outweigh the benefits, especially if you’re a guy.
You see, flax products are incredibly dense in compounds called “lignans”. In fact, flaxseeds are known of having dietary lignan levels 800-fold over that of most other foods1.
Why would this be a problem?
Well, not only are the lignans highly estrogenic2, there’s some evidence suggesting that they reduce total and free testosterone levels, while also suppressing the enzyme 5-a reductase3 which converts testosterone into its more potent form of dihydrotestosterone (DHT). Lignans work by increasing the levels of SHBG (sex hormone binding globulin), which binds into free-testosterone molecules and renders them “inactive” for the direct use of the androgen receptors.
The studies on the subject point heavily towards the conclusion that flaxseed products and androgens are not exactly a match made in heaven.
Firstly, there’s a case study of this 31-year old woman who had high testosterone levels which caused her to develop a condition called hirsutism4 (excessive facial hair growth). In an effort to control the hirsutism and drive down her high T-levels, the researchers told her to eat 30g/day of flaxseeds for 4 months. The results? Serum total testosterone dropped by a whopping 70%, and free-testosterone went down by a staggering 89%.
Well, you’re probably not a woman with hirsutism, so how would flaxseed consumption affect men’s hormone levels?
Turns out there’s a study where the same dose (30g/day) was given to 40 male subjects for a month5. The decrease in total testosterone was not nearly as significant as in the case-study above (only a mere ~10% decrease), but still, it’s evidence pointing towards the fact that flaxseeds can have a T-suppressing effect, even at such low dosages (2 tablespoons/day).
The same researchers had done a study with similar design (25 male subjects, 30g/day flaxseeds) 7 years earlier6. In that study, the average total testosterone levels dropped by ~15%, whereas free testosterone went down by ~20%. The difference in this previous study was that the subjects were told not to consume more than 20% of daily calories from dietary fat.
Few older in-vitro/animal studies have also shown that the lignans in flaxseed can increase SHBG count, thus resulting in lower bio-availability of testosterone for the receptors7,8.
So unless you’re a woman who battles with hirsutism, flaxseed is a food that lowers testosterone and I wouldn’t recommend eating too much of it.
I’m not sure how popular licorice is in the US, but here in Finland, and in many surrounding European countries, it’s regularly used in tobacco, teas, sweets, and chewing gums.
Even though it tastes amazing, and some alt-medicine “guru’s” claim that it would actually be super-healthy, the evidence points to one big problem.
The main compound in licorice – glycyrrhizic acid – which gives licorice root its phenomenal taste, has negative side effects and makes licorice a food that decreases testosterone…
…And this reduction in testosterone (although easily reversible) is not insignificantly small either.
The negative effects of glycyrrhizic acid on T-production were first seen in this test-tube study9, where the researchers found out that a very modest dose of glycyrrhetinic acid (hydrogenated version of glycyrrhizic acid), was able to significantly block testosterone production in isolated rat leydig cells, through inhibiting the activity of 17β-HSD enzyme, which is needed as a catalyst in testosterone production.
11 years later, glycyrrhizic acid was tested on human subjects. In a study where seven healthy male subjects were given 7g/day of licorice through a commercially available candy tablets (containing 0,5 grams of glycyrrhizic acid). Four days into the study and the subjects total testosterone levels had decreased from 740 ng/dL to 484 ng/dL10.
In other words, their testosterone levels were almost half of what they were before popping the licorice pills.
Good news are that 4 days after discontinuation of the licorice-habit, their testosterone levels had returned back to baseline.
3. High-PUFA Vegetable Oils
The majority of the cooking oils used all around the world in this 20th century, are refined vegetable oils, aka. liquid oils extracted from plant sources, which are then processed in various ways.
To begin with, most of the vegetable oils are incredibly bad choices for cooking, due to their low smoke point, and the often used refining process (bleaching, deodorizing, degumming, etc) which strips them of micronutrients and can leave traces of sulfates.
Even if not used for cooking, but just as is, high-PUFA (polyunsaturated fatty-acid) vegetable oils are a disaster for your testosterone production.
There’s a well-done study from the 90’s11.
Which clearly demonstrates in human male subjects, how:
- increased total fat intake boosts testosterone levels
- increased intake of saturated fatty-acids (SFA) boost testosterone levels
- increased intake of monounsaturated fatty-acids boosts testosterone levels
- and increased intake of polyunsaturated fatty-acids (PUFA) reduces testosterone levels.
Nearly all vegetable oils are LOADED with PUFAs (with the exceptions of coconut oil, palm oil, avocado oil, and olive oil).
What can make a high-PUFA vegetable oil worse, is if the polyunsaturated fatty-acids are mainly comprised of the dreaded omega-6 fatty-acids.
This is because the human body operates best if we keep the omega-3 (ω3) to omega-6 (ω6) ratio somewhere close to 1:1 or 1:2, which is near of that of the paleolithic human (the average American now has this ratio at 1:16, which is sixteen times more of the omega-6).
When the ratio of ω3:ω6 shifts more and more towards higher amounts of omega-6, the systemic inflammation and oxidative stress of the body keep on creeping higher and higher, this in turn DRAMATICALLY increasing your risk of multiple chronic diseases prevalent in Western societies12.
It’s very much likely that one of the end-results of high omega-6 intake would also be lowered testosterone production, and even though I didn’t find any studies about the subject, I did stumble upon a study which shows that when the ω6 content of sperm is high (and conversely ω3 is low), men are likely to be infertile. Whereas, when the ratio is more in favor of the omega-3’s, the subjects are more likely to be fertile and have high-quality sperm13.
Bottom line: Dietary fat intake should be moderate-high for optimal testosterone production, and the amount of saturated fatty-acids (SFA), and monounsaturated fatty-acids (MUFA) should be prioritized. High-PUFA vegetable oils on the other hand, are a food that decreases testosterone levels and production. High-PUFA high-ω6 vegetable oils are a disaster.
4. Mint, Peppermint, Spearmint…
Many of the herbs from the “mentha”, or “mint” -family, including spearmint, peppermint, and various other hybrids, are somewhat known of having testosterone reducing effects.
For the sake of clarity, let’s focus on the two most common plants of the mint family; peppermint (Mentha spicata) and spearmint (Mentha piperita).
Both are heavily used for culinary and food manufacturing purposes, though they can also be found in many soaps, shampoos, cough-relievers, lip-balms, and in toothpaste. Most herbal teas also tend to contain plants or plant extracts from the mint family…
…And even though mint-products tend to taste and smell pretty great, their effect on testosterone levels may not be that awesome:
Much of the research about peppermint and spearmint on male testosterone levels comes from studies using male wistar rats as test subjects…
In a study conducted 11 years ago14, 48 rats were divided into 4 groups:
- Group one received commercial drinking water (control).
- Group two received 20g/L peppermint tea.
- Group three got 20g/L spearmint tea.
- Group four got 40g/L spearmint tea.
When compared to the control group, the peppermint tea at 20g/L reduced total testosterone levels by 23%, whereas the spearmint tea at 20g/L reduced total T by a whopping 51%. If you translate this into human dosages, 20g/L is the equivalent of steeping a cup of tea from 5 grams of tea leaves.
A study from 2008, showed that spearmint suppressed testosterone production and acted as anti-androgen in male rats15. The researchers theorized that spearmint works by inducing oxidative stress in hypothalamus resulting in down-regulation of T synthesis in testicles. Another rodent study conducted in 2014, found out that at 10-40mg/kg spearmint showed no significant toxic effects on the reproductive system, but still, a trend towards lowered testosterone levels was noted16.
What about human studies?
Unfortunately, there aren’t any trials done on human males. BUT spearmint has been shown to significantly reduce testosterone levels in women…
…Much like in the case of flaxseeds (see number #1 above), spearmint has been studied on women with high androgen levels, and whom battle with the main cause of that; hirsutism (excessive facial hair growth).
In one study, the researchers gave 21 women subjects a cup of spearmint tea, 2 times a day, for 5 consecutive days. Surprisingly, total testosterone levels didn’t change much, but the bio-available free-testosterone levels did drop by ~30% on average17. The study was replicated with 42 subjects in 2009, only the duration of the trial was changed to 30 days. The results showed that free and total testosterone levels were significantly reduced over the 30 day period in the women who drank spearmint tea18.
Are you a woman battling with hirsutism or a male wistarian rat? Probably not, so this isn’t direct proof that similar effects would be seen in human males. However, the studies above are still quite heavy evidence towards the fact that the herbs from the mint family and mint foods reduce testosterone levels in men.
Drinking alcohol of any kind has a significant trend of lowering testosterone levels. However, as it often is the case with alcohol, the dosage makes the poison.
In rodent studies, it’s often shown that alcohol has a dose-dependent testosterone suppressing effect19–22. One alarming study shows that when the rats are fed a diet where 5% of the calories come from alcohol, testicle size is reduced by 50%23.
In humans, heavy alcohol consumption is strongly correlated with lowered testosterone levels24–27, and chronic alcoholics tend to have much higher estrogen levels and much lower testosterone levels when compared to their non-alcoholic peers28–31.
It might come as a relief to some that lower amounts of alcohol are really not that bad for T production. Actually, 0,5g/kg of alcohol has been shown to slightly increase testosterone levels32, whereas an intake equivalent to ~2 glasses of red wine has been shown to only reduce T levels by a mere 7%33.
The most surprising results come from this Finnish study34, where it was noted that 1g/kg of alcohol (equivalent to ½ glass of vodka) taken immediately after a resistance training session, increased testosterone levels by ~100%! It’s uncertain why this happens, but the study at-hand is an excellent example of the fact that Finnish people tend to drink too much 😉
Alcohol tends to lower testosterone levels, but the dose really makes the poison, and few drinks are not going to turn you into an eunuch.
6. Soy Products
There are many controversial topics around soy consumption, one of them which is the legumes effect on testosterone levels.
Because of the high amount of phyto-estrogenic isoflavones (genistein, daidzein, glycitein) present in soybeans35, it’s often claimed that soy would elicit similar effects in the body as the principal female sex hormone; estrogen. In-vitro research has shown that although having a significantly lower affinity for the receptors than that of estrogen itself, isoflavones can still activate the estrogen receptors36 and downregulate the androgen receptors37.
Aside from isoflavones, soy is considered to be highly “goitrogenic”, meaning that it can disrupt the production of thyroid hormones by interfering with iodine uptake in the thyroid gland. Suppressed activity of the thyroid is considered to be one of the leading causes of low testosterone levels in men38.
The third possible “hormonal problem” with soy consumption is an anti-androgenic compound called equol39, which forms in the gut when the gut bacteria metabolizes the isoflavone; daidzen. According to research, this only happens in 30-50% of men40, due to the fact that not everyone has the “right” intestial bacteria to create equol.
It’s also worth mentioning that soybeans have – from a testosterone boosting point of view – quite bad fatty-acid ratios. out of the 20 grams of fat that can found in 100 grams of regular soybeans, more than 50% comes from the testosterone lowering PUFAs. Not to mention the fact that most of the PUFAs consist of the inflammatory omega-6 fatty-acids.
So at least on paper, soy seems to be a hormonal disaster, but what does the research say?
a) On multiple human and animal studies, it has been shown that high intake of soy (even if it’s coming through a low-isoflavone soy protein extract) can suppress both; testosterone and DHT.
b) Surprisingly enough, many studies also show that increased soy consumption does not correlate with lowered testosterone levels.
Bottom line: Even though the research is relatively inconclusive, I see no point in consuming high amounts of soy products (that is, at least if you’re a carnivore). There are many theoretical reasons for soy being a food that lowers testosterone levels, and the possible negative effects greatly outweigh the positive effects. In fact, the only positive effect of soy consumption seems to be the fact that it’s quite high in protein, and since being a plant, vegans/vegetarians could cover their dietary protein needs by eating a lot of soy products (though it’s worth mentioning that according to this study, animal protein is superior to plant protein when it comes to testosterone production).
Trans-fats are a common byproduct of a process called “hydrogenation”. In a nutshell, this is what happens:
Raw oils (usually soybean, cottonseed, safflower, corn, or canola) are hardened by passing hydrogen atoms through the oil in high pressure with the presence of nickel (which acts as an alkaline catalyst for the process). As an end result, some of the unsaturated molecules in the raw oils become fully saturated (and therefore also solid at room temperature). However, due to the demonization of saturated fat in mass-media, the hydrogenation process is often continued only to the point where the required texture is reached.
Now, the hydrogenation process flips some of the molecular “carbon-carbon” bonds into “trans” bonds, effectively creating trans-fatty acids. And when the hydrogenation process is completed only to the point where the optimal texture is reached (but not full hydrogenation), high amounts of trans-fatty-acids will remain in the end product.
So, if you’re wondering what foods are high in trans-fats, the most common ones would be the kind that includes the use of “hydrogenated” or “partially hydrogenated” vegetable oils:
- industrial vegetable oil shortenings for baking and confections
- margarine and vegetable oil spreads
- fast-foods, especially: Burger King, McDonald’s, and KFC
- potato chips (not all, but some)
- muffins and doughnuts
- cookies, cakes, cake mixes, and frostings
NOTE: There are many of the products above that are labeled “trans-fat free”, but this doesn’t automatically mean that they don’t include the stuff, since the FDA allows them to contain up to 0,5 grams of trans-fatty acids while still being “trans-fat free”. It’s also worth mentioning that during the summer, FDA announced a complete ban on all man-made partially hydrogenated fats from American foods by 2018.
But why are trans-fats bad for your health and testosterone production?
Firstly: Trans-fats promote systemic inflammation in the body41, and a recently published large review study concluded that each 2% increase in calories from trans-fats was associated with 23% increase in cardiovascular disease risk42.
Secondly: trans-fats are high in testosterone lowering PUFAs. They lower the amount of “good” HDL cholesterol43 (a crucial building block in testosterone synthesis). And a high intake of trans-fatty-acids is associated with lowered sperm counts and testosterone levels in male rodents44 and humans45.