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Flaxseed Effects on Testosterone

Our hormones have far-reaching effects on human health, with imbalances affecting everything from our mental state to our body composition. 

If you have confirmed or suspected low testosterone levels, naturally you want to correct the problem in order to reach optimal health. You want accurate information on which foods can raise or lower testosterone. 

This raises the question: can flaxseed lower testosterone? And whether or not it can, does it have health benefits that outweigh its risks? Let’s look at the evidence. 

Key Takeaways

  • Further research is needed on whether flaxseed consumption significantly affects male hormone levels, but regular flaxseed consumption may reduce high testosterone in women. 
  • This is despite its protective effects on hormone-dependent cancers and polycystic ovary syndrome. 
  • Foods such as mint, licorice, and processed foods, along with alcohol consumption, may cause a significant decrease in testosterone. 
  • Seafood, leafy green vegetables, and zinc-rich foods can benefit male hormones. 
  • A loss of male hormones has a range of adverse effects, including a decrease in muscle mass and an increase in body fat. 
  • In women, however, high testosterone negatively affects body composition and can lead to issues such as hair loss. 

How Does Flaxseed Affect Testosterone?

Flaxseed is thought to affect testosterone through its very high lignan content. Lignans are a type of phytochemical that may speed up the clearance of testosterone. With lignan intake, more testosterone that has made its way into the intestinal-liver circulation is caught there, bound to the lignans so it can be excreted. 

Lignans can also increase levels of sex hormone binding globulin (SHBG). SHBG attaches to both male and female hormones, preventing them from being active. Additionally, flaxseed lignans may reduce levels of 5 alpha-reductase, an enzyme that turbocharges testosterone by converting it to dihydrotestosterone. The lignan content of flaxseed is 800 times higher than most other foods [1]

The omega-3 polyunsaturated fatty acids in flaxseed could also play a role in reducing testosterone, at least among women with PCOS. A trial where women took 3 grams of omega-3 fats for eight weeks saw their blood levels of testosterone fall, while their menstrual cycles became more regular [2]

Flaxseed Effects on Testosterone: Should You Avoid It?

Overall, the effect of flaxseed on testosterone is inconclusive. Earlier, uncontrolled research suggested that flaxseed could reduce serum testosterone levels, but better quality studies found no difference. 

For Women

Women with polycystic ovary syndrome (PCOS) typically have high testosterone, which contributes to symptoms such as infertility and unwanted body hair. A clinical study on 41 women with the condition found that, while flaxseed powder supplementation improved measurements on insulin sensitivity and body weight, it didn’t reduce testosterone [3]

On the other hand, research on flaxseed oil, or the same omega-3 polyunsaturated fatty acids found in the oil, sometimes shows a reduction in testosterone among women with PCOS [2]

flaxseed effects on testosterone Effects of flaxseed supplementation on total serum testosterone in women
It was found that flaxseed reduced total serum testosterone over the course of four months

For Men

Flaxseed appeared to reduce testosterone among men with prostate cancer in an early study. When 25 men were waiting for surgery, they were assigned to a low-fat diet including 30 grams of flaxseed a day. Their average testosterone levels fell from 422 to 360ng/dL, and a measurement of tumor growth dropped, too [4]

However, these results were not repeated later on in a controlled trial. A large study of 161 men with the disease found that flaxseed did not lower testosterone compared to dietary fat restriction alone over the 30-day study period before surgery. However, all groups showed a fall in testosterone, which may have been caused by pre-surgery stress [5]

Health Benefits of Flaxseed

Flaxseed may help prevent the world’s biggest killer: cardiovascular disease. A trial involving men and older women, all with high cholesterol, tested the benefits of eating 50 grams of flaxseed a day in the form of muffins. Flaxseed significantly reduced LDL cholesterol, which is involved in the formation of dangerous artery plaques. However, it didn’t reduce testosterone [6]

The clinical trial on 161 men mentioned above found that flaxseed supplementation slowed down unhealthy cell proliferation. While not a treatment, this may mean flaxseed has a preventive effect [5]


Flaxseed may reduce testosterone levels through its lignans and omega-3 content. However, the evidence is inconclusive and points to either no effect or only a slight benefit. 

Foods That Lower Testosterone

Some foods may lower testosterone, which means you must avoid them if your levels are on the lower side. Among the testosterone-killing foods are:

flaxseed effects on testosterone

  • Mint.
  • Foods high in saturated fat.
  • Alcohol.
  • Licorice.


Mint, in particular spearmint, may reduce testosterone levels. A study involving 42 women with PCOS had them drink spearmint tea or a placebo for one month, to see what effect it had. Both their blood levels of testosterone and subjective ratings of male-pattern hair improved over the month, but a more objective scale of hair growth did not [7]

Saturated Fat

Saturated fat intake is associated with excessive calorie consumption, which leads to unwanted body fat. Being overweight in turn reduces sex hormone binding globulin, and impairs testosterone production. As low testosterone negatively affects your ability to build muscle mass and lose body fat, this leads to a harmful cycle [8]


Alcohol may unfortunately reduce your testosterone levels, even with moderate consumption. A small trial of 10 men and nine postmenopausal women found that just 40 grams of alcohol lowered testosterone in men by almost 7%, and worsened cholesterol levels too. This may have been caused by the 16.5% fall in DHEA levels, the precursor to our sex hormones [9]


Large amounts of licorice have shown the ability to significantly reduce testosterone. When a study tested a daily 7-gram dose of licorice root in 25 men, their testosterone levels fell by 26% in just one week.

There was only a slight fall in free testosterone levels, however, and testosterone production could still be stimulated. Progesterone, a “female” hormone, rose [10]


Certain foods, such as spearmint, alcohol, saturated fat-rich processed foods, and licorice, may reduce testosterone. Their mechanisms of action behind this include reduction in testosterone production and the stimulation of SHBG production. 

Foods That Boost Testosterone

On the other hand, there are many foods that increase testosterone. They include:

  • Seafood, particularly oily fish and shellfish.
  • Some leafy green vegetables.
  • Certain wholegrains.
  • Some nuts.


Both oily fish and shellfish may support healthy testosterone levels. Research shows that when men take omega-3 fatty acids, testosterone to luteinizing hormone (LH) levels rise by around 8%, and their testes grow larger. This is most likely because omega-3 fats increase the ability of testosterone-producing cells to respond to follicular stimulating hormone (FSH) [11]

Additionally, some shellfish are rich sources of zinc, including king crabs, lobsters, and some clams. Zinc prevents testosterone from being converted to estrogen, by inhibiting the aromatase enzyme [12]

Leafy Vegetables

Leafy green vegetables benefit your natural testosterone levels in two ways: through magnesium and acting as aromatase inhibitors. 

A study on magnesium supplementation found that it can increase testosterone in both male athletes and sedentary men. However, the athletes—recruited from Taekwondo practitioners in this study—showed greater improvements. These benefits were most likely because magnesium supports overall health, providing a buffer against stresses [13]

In the case of cruciferous vegetables, their aromatase-inhibiting properties have given them a reputation as protective against breast cancer. Through these powerful effects against the loss of testosterone to estrogen, you may be better able to maintain healthy testosterone levels [14]

Wholegrain Products

Wholegrain products have been endlessly promoted for their benefits in metabolic health and obesity prevention. As their fiber content can slow blood sugar absorption, they may improve insulin sensitivity. Research described above also shows that being overweight or insulin-resistant can increase SHBG and lower testosterone production [15]

Certain Nuts

Nuts are nutrient-dense foods that may support natural testosterone production too. Brazil nuts, cashew nuts, pecans, and pine nuts all contain at least 10% of the recommended zinc intake for men. Almonds, Brazil nuts, cashew nuts, and pine nuts are also rich sources of magnesium, supporting overall health and testosterone production indirectly [16]


Through mechanisms such as increasing zinc levels and promoting FSH sensitivity in cells responsible for producing testosterone, there are many foods that can support testosterone production. 

Signs of High Testosterone in Women

High testosterone in women has been linked to greater risks of developing PCOS and type II diabetes. One standard deviation increase in testosterone can increase the chance of developing PCOS by 50%, and diabetes by 37%. 

As for specific signs and symptoms, adverse effects of elevated testosterone in women feature [17] [18]:

  • Hirsutism, meaning thick, dark male-pattern hair. This should not be confused with soft, downy hair which happens to be darker, as seen in many Mediterranean and Middle Eastern women. Instead, it is “terminal” hair, like you see on a man’s face or body. 
  • Male-pattern hair loss. It is usually variable and diffuse, but women with more severe cases of high testosterone can show receding hairlines at the temples or front of the forehead. 
  • Acne, particularly that which does not respond to antibiotics or topical treatments. 
  • Increased body fat.
  • An increased risk of depression.
  • Signs such as unusually increased muscle mass, loss of breast tissue, and deepening of the voice are not typical of PCOS. These indicate a heightened testosterone level to the point of virilization and are seen with tumors or steroid use. 

How to Decrease Testosterone Levels in Women

There are a number of ways to bring testosterone back down to healthy levels in women. 

When you think about how to lower testosterone in women, start with metabolic health. The first lines of treatment include weight loss through diet and exercise, as insulin resistance and metabolic syndrome lead to high testosterone in cases of PCOS. Metformin is prescribed too if diet and lifestyle changes are not successful on their own. 

When successful, these treatments can not only reduce weight gain along with testosterone and androgen levels, but also restore healthy menstruation and ovulation. 

In addition to this, hormonal contraceptives are typically prescribed. Adding in estrogen and progesterone can counteract the effects of high testosterone levels, reduce 5 alpha-reductase, and inhibit the production of testosterone by the ovaries [18]

More natural methods of taming testosterone are described above. Spearmint, for example, could significantly reduce both testosterone and self-reported severity of male-pattern hair growth, but longer studies are needed to see if there is a significant effect or not. 

As for licorice, research where women took licorice root saw a drop in testosterone levels from 27.8 to 19ng/dL in just one menstrual cycle. It returned to the original levels once they stopped taking licorice, so you don’t need to worry about unwanted, long-term effects if you find too much difficulty with building muscle [19]

Remember that you don’t want to decrease your testosterone more than necessary. Low testosterone in women is likely to have similar negative effects on your ability to maintain muscle mass, keep body fat down, and maintain a healthy mental state. 


High testosterone levels in women lead to male-pattern body hair, including hair loss, weight gain, and acne. Treatment options include using diet and exercise to improve metabolic health, alongside pharmaceutical and natural methods of reducing testosterone and 5 alpha-reductase production. 

Signs of Low Testosterone in Men 

Signs of low testosterone in men are sometimes visible, and others can quietly impact your quality of life. They include [17]:

flaxseed effects on testosterone

  • Impaired sexual function, including sperm quality and the ability to ejaculate. 
  • Loss of muscle mass, or difficulty in building muscle to reach your fitness goals.
  • A decline in muscle strength.
  • Increased body fat, in particular abdominal fat. 
  • Reduced bone mineral density, which you may only notice after a fracture if it is severe enough.

How to Increase Testosterone in Men 

When it comes to medical treatment, testosterone replacement therapy is the mainstay of raising testosterone back to healthy, youthful levels. 

However, there are many dietary and lifestyle interventions that you can use in less severe cases. Higher dietary intakes of bread, pastries, desserts, dairy products, and fast or processed foods were linked to lower testosterone levels in men. On the other hand, leafy green vegetables and home-cooked meals (which are lower in refined ingredients) had the opposite effect [8]

As for specific nutrients, zinc and omega-3 fatty acids can work together to support healthy sex hormone metabolism. Zinc can prevent the enzyme aromatase from “stealing” testosterone for use as estrogen, while omega-3 fats sensitize testosterone-producing cells to FSH. It is the hormone FSH that triggers the generation of testosterone [11] [12]

And if you’re asking, “does working out increase testosterone?,” yes; regular exercise does boost testosterone levels. However, heavy resistance exercise can cause a drop in the hormone if you aren’t used to it, or if you overtrain [13]


A loss of testosterone in men leads to a loss of muscle mass, increased body fat, and a decline in mental health. Fortunately, working out and a healthy diet that includes zinc and omega-3 fatty acids can support your testosterone production, and you have testosterone replacement therapy to fall back on, too. 


What are the most important things to know about flaxseed’s effects on testosterone? 

Does Flaxseed Increase Testosterone?

There is no evidence that consumption of flaxseed directly increases testosterone production. However, one small study found that an energy-restricted “cleanse” diet with supplementation led to a significant increase in testosterone levels. The cleanse supplement contained a range of ingredients, and among them was flaxseed. Dietary flaxseed certainly did no harm [20]

Is Flaxseed Good for Males?

Clinical nutrition research demonstrates that eating flaxseed may have protective effects when it comes to prostate cancer. Even in studies where it didn’t reduce testosterone, flaxseed could still slow cell growth in prostate tumors. 

Can Flaxseed Cause Erectile Dysfunction?

As flaxseed does not seem to significantly reduce testosterone levels in real-world practice, it should not cause erectile dysfunction. 

If anything, choosing to consume flaxseed daily should improve erections. The cardiovascular health benefits of dietary flaxseed include a reduction in cholesterol among people with peripheral artery disease. This means it may help to maintain healthy circulation, something needed to maintain erections [21]

Does Flaxseed Mess With Your Hormones?

There is mixed evidence that flaxseed has a significant, direct hormonal effect, despite its benefits in heart health, cancer prevention, and cases of PCOS. However, its omega-3 fatty acid content may indirectly benefit hormonal balance, by making your testosterone-producing cells more responsive to the FSH they need to get started. 


No single food can have the same effect on sex hormones as hormone replacement therapy. While a healthy diet can shift testosterone levels up or down, such as if you regularly enjoy seafood and other zinc-rich foods, or drink large amounts of alcohol, you must use a holistic approach. 

If necessary, hormone replacement therapy has its place, too, but it is best to use this as a last resort, after supporting your body’s own production has turned out to be unsuccessful. 


  1. Nowak, Debra A et al. “The Effect of Flaxseed Supplementation on Hormonal Levels Associated with Polycystic Ovarian Syndrome: A Case Study.” Current topics in nutraceutical research vol. 5,4 (2007): 177-181.
  2. Nadjarzadeh, Azadeh et al. “The effect of omega-3 supplementation on androgen profile and menstrual status in women with polycystic ovary syndrome: A randomized clinical trial.” Iranian journal of reproductive medicine vol. 11,8 (2013): 665-72.
  3. Haidari F, Banaei-Jahromi N, Zakerkish M, Ahmadi K. The effects of flaxseed supplementation on metabolic status in women with polycystic ovary syndrome: a randomized open-labeled controlled clinical trial. Nutr J. 2020 Jan 24;19(1):8. doi: 10.1186/s12937-020-0524-5. PMID: 31980022; PMCID: PMC6982376.
  4. Demark-Wahnefried, W et al. “Pilot study of dietary fat restriction and flaxseed supplementation in men with prostate cancer before surgery: exploring the effects on hormonal levels, prostate-specific antigen, and histopathologic features.” Urology vol. 58,1 (2001): 47-52. doi:10.1016/s0090-4295(01)01014-7 
  5. Demark-Wahnefried, Wendy et al. “Flaxseed supplementation (not dietary fat restriction) reduces prostate cancer proliferation rates in men presurgery.” Cancer epidemiology, biomarkers & prevention : a publication of the American Association for Cancer Research, cosponsored by the American Society of Preventive Oncology vol. 17,12 (2008): 3577-87. doi:10.1158/1055-9965.EPI-08-0008 
  6. Jenkins, D J et al. “Health aspects of partially defatted flaxseed, including effects on serum lipids, oxidative measures, and ex vivo androgen and progestin activity: a controlled crossover trial.” The American journal of clinical nutrition vol. 69,3 (1999): 395-402. doi:10.1093/ajcn/69.3.395 
  7. Grant, Paul. “Spearmint herbal tea has significant anti-androgen effects in polycystic ovarian syndrome. A randomized controlled trial.” Phytotherapy research : PTR vol. 24,2 (2010): 186-8. doi:10.1002/ptr.2900 
  8. Hu, Tzu-Yu et al. “Testosterone-Associated Dietary Pattern Predicts Low Testosterone Levels and Hypogonadism.” Nutrients vol. 10,11 1786. 16 Nov. 2018, doi:10.3390/nu10111786 
  9. Sierksma, Aafje et al. “Effect of moderate alcohol consumption on plasma dehydroepiandrosterone sulfate, testosterone, and estradiol levels in middle-aged men and postmenopausal women: a diet-controlled intervention study.” Alcoholism, clinical and experimental research vol. 28,5 (2004): 780-5. doi:10.1097/01.alc.0000125356.70824.81 
  10. Armanini, D et al. “Licorice consumption and serum testosterone in healthy man.” Experimental and clinical endocrinology & diabetes : official journal, German Society of Endocrinology [and] German Diabetes Association vol. 111,6 (2003): 341-3. doi:10.1055/s-2003-42724 
  11. Jensen, Tina Kold et al. “Associations of Fish Oil Supplement Use With Testicular Function in Young Men.” JAMA network open vol. 3,1 e1919462. 3 Jan. 2020, doi:10.1001/jamanetworkopen.2019.19462 
  12. Solomons, Noel W. “Dietary Sources of Zinc and Factors Affecting Its Bioavailability.” SAGE Journals, (2001) 
  13. Cinar, Vedat et al. “Effects of magnesium supplementation on testosterone levels of athletes and sedentary subjects at rest and after exhaustion.” Biological trace element research vol. 140,1 (2011): 18-23. doi:10.1007/s12011-010-8676-3 
  14. Licznerska, Barbara E et al. “Modulation of CYP19 expression by cabbage juices and their active components: indole-3-carbinol and 3,3′-diindolylmethene in human breast epithelial cell lines.” European journal of nutrition vol. 52,5 (2013): 1483-92. doi:10.1007/s00394-012-0455-9 
  15. Belobrajdic, Damien P, and Anthony R Bird. “The potential role of phytochemicals in wholegrain cereals for the prevention of type-2 diabetes.” Nutrition journal vol. 12 62. 16 May. 2013, doi:10.1186/1475-2891-12-62 
  16. Tan, Sze-Yen et al. “Can Nuts Mitigate Malnutrition in Older Adults? A Conceptual Framework.” Nutrients vol. 10,10 1448. 6 Oct. 2018, doi:10.3390/nu10101448 
  17. Ruth, Katherine S et al. “Using human genetics to understand the disease impacts of testosterone in men and women.” Nature medicine vol. 26,2 (2020): 252-258. doi:10.1038/s41591-020-0751-5 
  18. Rasquin Leon LI, Anastasopoulou C, Mayrin JV. Polycystic Ovarian Disease. [Updated 2021 Jul 21]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2021 Jan-. Available from: 
  19. Armanini, Decio et al. “Licorice reduces serum testosterone in healthy women.” Steroids vol. 69,11-12 (2004): 763-6. doi:10.1016/j.steroids.2004.09.005 
  20. Balliett, Mary, and Jeanmarie R Burke. “Changes in anthropometric measurements, body composition, blood pressure, lipid profile, and testosterone in patients participating in a low-energy dietary intervention.” Journal of chiropractic medicine vol. 12,1 (2013): 3-14. doi:10.1016/j.jcm.2012.11.003
  21. Edel, Andrea L et al. “Dietary flaxseed independently lowers circulating cholesterol and lowers it beyond the effects of cholesterol-lowering medications alone in patients with peripheral artery disease.” The Journal of nutrition vol. 145,4 (2015): 749-57. doi:10.3945/jn.114.204594 

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