Do Seed Oils Affect Testosterone? The Science Behind Dietary Fats and Hormones

November 19, 2025 •

4 min read

According to a 2017 study, a high intake of trans fatty acids, often derived from processed seed oils, was associated with lower total and free testosterone in young, healthy men. The relationship between seed oils and testosterone is not as simple as it seems, with nuance dependent on the specific type of fat and overall dietary pattern.

Quick Summary

This article analyzes the scientific research on seed oils and testosterone. It covers the roles of different fatty acids, conflicting study results, and how overall dietary patterns influence hormone production.

Key Points

Conflicting Evidence: Research on seed oils and testosterone is inconsistent; some studies suggest high polyunsaturated fat (PUFA) intake is linked to lower testosterone, while others show no independent association.
The Problem with Trans Fats: Intake of trans fatty acids, often found in processed foods made with seed oils, is more consistently linked to lower testosterone and reduced testicular volume.
Omega-6 vs. Omega-3: An imbalance favoring too many omega-6 fatty acids over omega-3s, common with diets high in certain seed oils, may contribute to hormonal disruption and inflammation.
The Role of Healthy Fats: Adequate intake of saturated and monounsaturated fats from whole food sources is crucial for cholesterol, the precursor to testosterone, supporting hormone synthesis.
Don't Go Low-Fat: Extremely low-fat diets have been shown to decrease testosterone levels, emphasizing the need for a sufficient intake of healthy fats from a balanced diet.
Overall Diet Matters Most: Focusing on a balanced diet rich in whole foods, rather than fixating on a single food item, is the most effective approach for supporting hormonal health.

The Complex Relationship Between Dietary Fats and Hormone Production

For years, dietary fat has been a subject of intense debate in nutritional science. With the rise of modern processed foods and the increased consumption of seed oils like soybean, corn, and canola oil, many have questioned their impact on health, including hormone regulation. Testosterone, a steroid hormone, is synthesized from cholesterol. This means that the type of fat consumed can provide the building blocks needed for hormone production, but the specific type of fat matters significantly.

The Science Behind Steroid Hormone Synthesis

Steroid hormones, including testosterone, are derived from cholesterol. The body needs a steady supply of healthy fats to produce them efficiently. Traditionally, saturated fats were viewed as unhealthy, but recent research suggests they are vital for synthesizing steroid hormones. Conversely, certain types of fat, particularly some polyunsaturated and trans fats, may disrupt this delicate process.

Examining the Evidence: Conflicting Study Results

The scientific literature on seed oils and testosterone presents a mixed and often contradictory picture. This complexity arises from variations in study design, sample size, fat types, and overall dietary context.

High Polyunsaturated Fat Intake and Its Effects

Many seed oils are rich in polyunsaturated fatty acids (PUFAs), particularly omega-6 fatty acids. Some studies have linked high intakes of PUFAs to lower testosterone levels. For instance:

A 2000 study involving 69 Japanese men found that higher consumption of polyunsaturated fats was associated with significantly lower testosterone levels.
A 2019 study on men with hypogonadism observed that diets high in polyunsaturated fatty acids decreased serum testosterone production.
Research from 2017 found that a high intake of omega-6 PUFAs was inversely related to testicular volume in young men.

The Negative Impact of Trans Fats

Trans fats, often found in processed and hydrogenated oils, are more consistently linked to negative health outcomes. A 2017 study on 209 men showed that those with the highest trans fat intake had 15% lower testosterone levels and 37% lower sperm counts compared to those with the lowest intake. Since trans fats are a byproduct of industrial processing and frequently found in foods containing seed oils, avoiding these processed items is a key step in supporting hormonal health.

The Omega-6 to Omega-3 Balance

The ratio of omega-6 to omega-3 fatty acids in the diet is critical for overall health and hormone regulation. While some omega-6s are necessary, excessive intake relative to omega-3s can promote inflammation and potentially disrupt hormonal balance. Interestingly, a 2022 animal study found that omega-6 highly unsaturated fatty acids were required for steroid hormone production in Leydig cells, adding a new layer of complexity to the discussion. This suggests that a balanced intake, rather than outright elimination, is important.

Low-Fat Diets Can Also Be Problematic

Paradoxically, severely restricting fat intake may also negatively impact testosterone levels. A 2021 meta-analysis concluded that low-fat diets decreased men's testosterone levels by 10-15% on average. The study noted that diets very low in fat, particularly vegetarian ones, showed even more significant decreases. This emphasizes that adequate fat, from healthy sources, is crucial.

Comparison of Different Fat Types and Their Potential Impact on Testosterone


Fat Type	Common Sources	Potential Impact on Testosterone	Supporting Evidence
Saturated Fats	Butter, ghee, unprocessed meat	Can serve as a building block for steroid hormones, potentially stabilizing levels.	Conflicting findings; some studies show no independent correlation, but low-fat diets are linked to lower T.
Omega-3 PUFAs	Fatty fish (salmon), walnuts, flaxseed	May improve testicular size and function. Supports overall hormonal balance by reducing inflammation.	Associated with improved testicular volume and increased testosterone in men taking DHA-rich supplements.
Omega-6 PUFAs	Corn oil, soybean oil, safflower oil	High intake is potentially linked to lower testosterone levels. The ratio to Omega-3 is important.	Some studies show an inverse relationship with total testosterone and testicular volume.
Trans Fats	Processed foods, partially hydrogenated oils	Strongly and consistently associated with lower total and free testosterone.	Higher trans fat intake linked to lower testosterone and sperm count in multiple studies.

Practical Recommendations for Optimizing Hormonal Health

Based on the current body of research, here are some actionable steps for managing dietary fat intake to support healthy testosterone levels:

Focus on the overall diet: Instead of demonizing a single food group, concentrate on a balanced diet rich in whole foods. A Mediterranean-style diet, for instance, is often linked to positive health outcomes.
Improve the omega ratio: Increase your intake of omega-3 fatty acids by consuming fatty fish, flaxseed, and walnuts, while moderating your consumption of foods high in omega-6s.
Prioritize healthy cooking fats: Choose monounsaturated and saturated fats from whole food sources for cooking, such as olive oil, coconut oil, and butter.
Eliminate processed foods: Avoid processed foods and fast food, which are major sources of harmful trans fats and poor-quality seed oils.
Don't fear fat: Don't follow a very low-fat diet, as adequate fat intake is necessary for hormone production. Aim for a balanced intake from a variety of healthy sources.

Conclusion: What We Know About Seed Oils and Testosterone

The question of whether seed oils affect testosterone is a complex one with no simple answer. The evidence suggests that a diet high in processed foods containing trans fats and an unfavorable omega-6 to omega-3 ratio can negatively impact testosterone levels. However, the issue is not necessarily the seed oil itself but rather the specific fatty acid profile and the overall dietary context. Some studies on pure seed oil consumption show mixed results, and animal studies don't always translate directly to humans. The strongest evidence points to avoiding processed and hydrogenated oils, balancing your omega-6 and omega-3 intake, and ensuring sufficient intake of healthy fats from whole food sources to support hormonal health.

For more detailed information on a specific study linking fat intake to reproductive hormones, you can review the full text here: Fatty acid intake in relation to reproductive hormones and testicular function in young healthy men.

Frequently Asked Questions

No, it is not accurate to say all seed oils lower testosterone. The effect depends on the type of fatty acids in the oil. Issues are more consistently linked to trans fats and an imbalance favoring too many omega-6 polyunsaturated fatty acids, not all seed oils universally.

Research provides conflicting data. Some evidence suggests saturated fats are crucial building blocks for hormones, while high intake of omega-6 polyunsaturated fats might negatively impact testosterone. The best approach is a balanced diet with a mix of healthy fat types.

Seed oils used in heavily processed or fried foods, which can contain trans fats, are most problematic. For instance, partially hydrogenated vegetable oils are high in trans fats and are strongly linked to lower testosterone. Specific seed oils high in omega-6s, like canola or soybean oil, are associated with lower testosterone in some studies, but results are mixed.

Avoiding processed foods and trans fats (which are often found in products made with seed oils) may help increase testosterone, especially if your current diet is poor. However, simply avoiding seed oils while maintaining an unbalanced diet may not have a significant impact.

The balance of omega-6 and omega-3 fatty acids is important. A diet with an excessively high omega-6 to omega-3 ratio can lead to inflammation, which may negatively influence hormone production. Many seed oils contribute heavily to the omega-6 intake in Western diets.

Switching to oils rich in monounsaturated fats (like olive oil) and saturated fats from whole food sources (like coconut oil) can help improve your overall fat intake profile. This can be a beneficial change for general health and supporting testosterone levels.

Studies suggest that high intake of trans fats impairs testicular function, leading to lower total and free testosterone levels and reduced testicular volume. These fats interfere with the body's ability to produce hormones effectively.