Do Seed Oils Lower Testosterone? The Science Behind the Controversy

Written By The Mr. Fertyl Research & Education Team

Seed oils – like canola, soybean, sunflower, corn, and other vegetable oils – have become a hot topic in men’s health. On social media and forums, you’ll find claims that these oils “kill testosterone” or harm male fertility. It’s an alarming idea, because testosterone is crucial for things like muscle mass, energy, libido, and sperm production. But is there truth behind the claims that seed oils lower testosterone? This article takes a friendly, informative look at the science, cutting through myths to see what research really shows. Along the way, we’ll also discuss how choosing healthier fats (and even the right underwear) can support hormonal balance and fertility.

Seed Oils and Testosterone: Why the Controversy?

The controversy mainly centers on the fatty acid profile of seed oils. These oils are high in polyunsaturated fatty acids (PUFAs), especially omega-6 fats (like linoleic acid). In theory, a high intake of omega-6 could promote inflammation or oxidative stress in the body, which some fear might disrupt hormone production. For example, linoleic acid can convert into arachidonic acid – a building block for certain pro-inflammatory compounds [10]. The worry is that chronic inflammation could suppress testosterone. Indeed, some studies have observed that men who consume more PUFAs tend to have slightly lower testosterone levels [8]. An older study in Japan found that men eating diets rich in polyunsaturated fats had significantly lower testosterone than those eating less PUFA [2]. And in one 2019 experiment on men with low testosterone, a high-PUFA diet was linked to decreased testosterone production [2]. These findings fuel the speculation that “vegetable oils” may be testosterone antagonists.

However, it’s not so simple. Many experts point out that omega-6 fats aren’t inherently “toxic”. In fact, only a small fraction of dietary linoleic acid is converted to inflammatory arachidonic acid in the body [10]. Most research reviews have found no clear evidence that normal amounts of omega-6 from foods cause chronic inflammation on their own [10]. As the Johns Hopkins School of Public Health bluntly states, “Seed oils do not cause inflammation, [the] concern...is based on a misunderstanding” of omega-6s [11]. Omega-6 fats are essential nutrients and, when consumed as part of a balanced diet, they co-exist with omega-3 fats to support health. The key may lie in balance: modern diets often have an excess of omega-6 relative to omega-3. Rather than cutting out seed oils entirely, researchers suggest adding more omega-3 (from fish, flaxseed, walnuts, etc.) to improve the ratio [11] – because omega-3s are strongly anti-inflammatory and support healthy hormone function.

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What Does the Research Actually Say?

When we look at scientific studies, the picture is mixed. Some evidence does suggest a connection between high-PUFA oils and lower testosterone – but often with important caveats. For example, a recent study of over 2,500 middle-aged men in Finland initially noted that those who ate more polyunsaturated fat had slightly lower total and free testosterone on average [8]. Interestingly, men with higher saturated fat intake (think butter or animal fat) showed higher T levels in that basic analysis [8]. This seems to support the seed-oil skeptics. But after the researchers adjusted for other factors like body weight, exercise, and overall diet quality, those differences became not statistically significant [8]. In other words, once they accounted for general lifestyle, the type of fat alone didn’t independently drive testosterone levels. Their conclusion: dietary fat quality by itself was not an independent determinant of testosterone in reasonably healthy men [12].

Likewise, a systematic review on low-fat vs. higher-fat diets found only a modest effect of diet fat on testosterone, and urged caution in over-interpreting small short-term changes [8]. It appears that factors like losing excess weight, exercising, and getting enough sleep may have a much bigger impact on testosterone than whether your salad dressing is made with soybean oil or olive oil.

It’s also worth noting some fascinating animal studies that highlight how complex this topic is. In one study on rats, those fed a canola oil-rich diet had significantly lower testosterone levels than rats fed soybean oil [13]. (Canola and soybean are both seed-derived oils, but their fatty acid profiles differ.) This finding hinted that certain processed oils might negatively affect hormone metabolism in that model. Yet, a different study on mice found the opposite outcome: when researchers added a large amount of soybean oil to the mice’s diet for 16 weeks, the mice actually ended up with higher testosterone levels than a control group [14]. The high-PUFA intake in that case seemed to stimulate the animals’ hormone pathways (possibly by raising luteinizing hormone, which signals the testes to produce T) [14]. These are extreme scenarios, but they underline that the biological effects of fats can vary and are not one-dimensional.

Should You Switch to Olive, Avocado, or Coconut Oil?

Given the debate, many people wonder if they should avoid seed oils and use alternatives like extra-virgin olive oil, avocado oil, or coconut oil. From a general health perspective, olive and avocado oils are excellent choices – not because seed oils are “poison,” but because olive and avocado are high in monounsaturated fats and antioxidants. Monounsaturated fats (like oleic acid in olive oil) are considered heart-healthy and may also support hormone health. In one small trial, men who switched from butter to extra-virgin olive oil (or argan oil) for just three weeks saw a notable increase in their testosterone levels – about a 17–20% boost, along with higher luteinizing hormone levels [15]. The researchers concluded that these plant oils had a positive effect on the men’s androgen profile [15]. Diets rich in olive oil (such as the Mediterranean diet) have been linked to many benefits, and maintaining good overall health can certainly help keep testosterone in balance.

What about coconut oil? Coconut and palm oils are high in saturated fats. Some older studies suggested that men eating more saturated fat had slightly higher testosterone than those on very low-fat diets [8]. Saturated fat might increase testosterone indirectly by providing ample cholesterol (the raw material for making steroid hormones). However, loading up on saturated fats isn’t a magic bullet for high T – and it carries well-known downsides for cardiovascular health. Excess saturated fat can raise LDL (“bad”) cholesterol and increase heart disease risk [11]. So while using a bit of coconut oil in your cooking likely won’t harm your testosterone, it’s wise to enjoy it in moderation and focus mainly on unsaturated fats.

In summary, there’s no need to demonize all seed oils, but there are sensible reasons to diversify your fat sources. Moderation and balance are key. You might use olive or avocado oil for salad dressings and sautéing, choose canola or peanut oil for high-heat cooking (since they have high smoke points and a neutral flavor), and ensure you get omega-3 fats from foods like fish or flaxseed to round out the omega-6 from seed oils. This balanced approach supports overall health and a favorable environment for hormone production.

Beyond Diet: Lifestyle Tips for Healthy Testosterone and Fertility

It’s important to remember that testosterone levels and male fertility depend on more than just the oils in your pantry. Overall lifestyle plays a huge role in hormonal health. Regular exercise (especially strength training), maintaining a healthy weight, managing stress, and getting enough sleep all help optimize testosterone production [12]. Additionally, avoid smoking and excessive alcohol, as both can negatively impact T levels and sperm quality. Diet-wise, make sure you’re getting plenty of protein, zinc, vitamin D, and antioxidant-rich fruits and veggies – these nutrients support testosterone and reproductive health [8].

Another often-overlooked factor is temperature and clothing. The testes need to stay a few degrees cooler than body temperature for ideal sperm production. Tight, non-breathable underwear can raise scrotal temperature and potentially impair sperm output over time [16]. If you’re trying to boost your fertility, something as simple as switching your underwear could help. Research from Harvard shows that men who usually wore loose-fitting boxers had ~25% higher sperm concentrations and significantly higher total sperm counts than men who wore snug briefs [16]. The men in boxers also had lower levels of follicle-stimulating hormone, suggesting their bodies weren’t straining to compensate for any heat-related sperm loss [16]. The takeaway? Keeping things cool and comfortable “down there” is beneficial for fertility.

This is where Mr. Fertyl’s Bamboo Lyocell underwear comes in as a smart, health-conscious choice. These eco-friendly underwear are made from breathable bamboo fibers that help wick moisture and dissipate heat – exactly what you want for an optimal reproductive environment. By wearing comfortable, temperature-regulating underwear like Mr. Fertyl’s, you’re not only investing in sustainable, high-quality fabric, but also taking a proactive step for your fertility. It’s a simple lifestyle tweak that, alongside a balanced diet (and maybe swapping some seed oils for olive oil), can make a positive difference.

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Conclusion: Finding Balance and Focusing on Health

So, do seed oils lower testosterone? There isn’t a clear-cut yes or no answer. The most reliable evidence suggests that typical amounts of seed oils in your diet are unlikely to dramatically drop your testosterone. While extremely high intakes of omega-6 fats (with very low omega-3s) might have some negative hormonal effects, it’s equally possible that other diet and lifestyle factors are the real culprits behind lowered T in those cases. In reality, seed oils contain essential fatty acids and Vitamin E, and they can be part of a healthy diet when used in moderation. The scariest claims about them “destroying” male hormones are not supported by mainstream endocrinology [10][11].

If you’re concerned about your testosterone or fertility, look at the bigger picture. Improving your overall diet (for instance, reducing added sugars and ultra-processed junk), exercising regularly, and ensuring you have a good omega-6/omega-3 balance will likely yield better results than fixating on one ingredient. You can certainly choose olive oil, avocado oil, or other alternatives for their health benefits – they’re great options and might give you peace of mind. And remember the little things that add up: managing stress, getting sleep, and yes, wearing breathable underwear to keep things cool.

In the end, the “seed oils vs testosterone” controversy teaches us to stay curious but also skeptical of extreme claims. By sticking to science-backed information and taking a holistic approach to your health, you can support your testosterone levels and fertility naturally. Enjoy a variety of healthy fats, take care of your body, and don’t let fear of a single food oil drive you crazy. Here’s to finding balance – for your hormones, your fertility, and even the planet’s well-being.

  1. Harvard T.H. Chan School of Public Health. (2022, June 22). Scientists debunk claims of seed oil health risks. Harvard Public Health News. Source.
  2. Ferguson, S. (2023, February 21). 10 Testosterone-Killing Foods. Healthline. Source.
  3. Nagata, C., Takatsuka, N., Kawakami, N., & Shimizu, H. (2000). Relationships between types of fat consumed and serum estrogen and androgen concentrations in Japanese men. Nutrition and Cancer, 38(2), 163–167. Source.
  4. Whittaker, J., & Wu, K. (2021). Low-fat diets and testosterone in men: Systematic review and meta-analysis of intervention studies. Journal of Steroid Biochemistry and Molecular Biology, 210, 105878. Source.
  5. Mínguez-Alarcón, L., Chavarro, J. E., Mendiola, J., et al. (2017). Fatty acid intake in relation to reproductive hormones and testicular volume among young healthy men. Asian Journal of Andrology, 19(2), 184–190. Source.
  6. Mayo Clinic Staff. (2025). Mediterranean diet benefits for men: heart, hormones and healthy aging. Mayo Clinic Diet Blog. Source.
  7. Bole, R. (2025, September 17). How To Increase Sperm Count and Improve Male Fertility. Cleveland Clinic – Health Essentials. Source.
  8. Toshniwal Paharia, P. (2023, November 23). Dietary saturated fats may influence male hormone levels, new study suggests. News-Medical. Source.
  9. Wenzel, A. (2023). Foods That Lower Testosterone: The Real Culprits Behind Declining Male Vitality. Brentwood MD. Source.
  10. Academy of Nutrition and Dietetics. (2025, June). Nutrition Fact Check: Seed oils. Source.
  11. Rosen, A. (2025, June 6). Influence vs. evidence: The science supporting seed oils. Johns Hopkins Bloomberg School of Public Health. Source.
  12. Wynne-Ellis, M. M., Mursu, J. J., Tuomainen, T.-P., Bertone-Johnson, E., Salonen, J. T., & Virtanen, J. K. (2024). Dietary fat quality and serum androgen concentrations in middle-aged men. European Journal of Clinical Nutrition. Source.
  13. Okuyama, H., Ohara, N., Tatematsu, K., Fuma, S., Nonogaki, T., Yamada, K., Ichikawa, Y., Miyazawa, D., Yasui, Y., & Honma, S. (2010, October). Testosterone-lowering activity of canola and hydrogenated soybean oil in the stroke-prone spontaneously hypertensive rat. Journal of Toxicological Sciences, 35(5), 743–747. Source.
  14. Su, Y., Tian, Z., Qi, X., Luo, D., Liu, L., Liu, S., Zheng, D., Wei, F., He, Z., & Guan, Q. (2021). Effects of increasing intake of soybean oil on synthesis of testosterone in Leydig cells. Nutrition & Metabolism, 18, Article 53. Source.
  15. Derouiche, A., Jafri, A., Driouch, I., El Khasmi, M., Adlouni, A., Benajiba, N., Bamou, Y., Saile, R., & Benouhoud, M. (2013). Effect of argan and olive oil consumption on the hormonal profile of androgens among healthy adult Moroccan men. Natural Product Communications, 8(1), 51-53. Source.
  16. Mandal, A. (2018, August 8). Study looks at boxer shorts versus underpants and sperm count. News-Medical. Source.