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Does Citrulline Increase Testosterone?

Brief Answer: Current scientific evidence does not conclusively support the claim that citrulline directly increases testosterone levels. While citrulline may have benefits related to blood flow and exercise performance, its direct impact on testosterone production remains unproven.

The relationship between citrulline and testosterone has been a topic of interest in the health and fitness community. Citrulline, a non-essential amino acid, has gained attention for its potential benefits in various areas of health. This article explores the current scientific understanding of citrulline’s effects on testosterone levels and related physiological processes.

Understanding Citrulline and Its Functions

Citrulline is an amino acid naturally produced in the body and found in certain foods, particularly watermelon. Its primary function involves the production of nitric oxide (NO), a compound that plays a crucial role in vasodilation and blood flow regulation. When consumed, citrulline converts to arginine in the kidneys, which then leads to increased NO production.

The body’s ability to produce NO has significant implications for various physiological processes, including cardiovascular health and exercise performance. This connection has led researchers to investigate citrulline’s potential effects on other aspects of health, including hormone production.

The Theoretical Link Between Citrulline and Testosterone

The potential connection between citrulline and testosterone stems from the amino acid’s impact on blood flow and NO production. Improved blood circulation could theoretically enhance the delivery of nutrients and oxygen to the testes, potentially supporting testosterone production. Still this mechanism remains largely theoretical and lacks substantial clinical evidence.

According to a study, citrulline supplementation increased serum levels of L-arginine and NO, which are precursors to testosterone production. Still it’s crucial to note that this study did not directly measure testosterone levels, leaving the direct impact on testosterone production unclear.

Animal Studies: Promising but Limited

Research conducted on animals has shown some promising results regarding citrulline’s effects on male sexual function. One study found that citrulline supplementation improved erectile function in rats, a condition often associated with testosterone levels. Still it’s crucial to remember that animal studies have limited applicability to human physiology, and these findings cannot be directly translated to human outcomes.

Human Studies: Mixed Results and Limited Evidence

Human studies investigating citrulline’s impact on testosterone levels have produced mixed results. A clinical study involving 24 men with erectile dysfunction found that 1.5 grams of citrulline daily improved erection hardness in half of the participants compared to the placebo group. Still this study did not measure testosterone levels directly, making it difficult to draw conclusions about citrulline’s effect on the hormone.

Indirect Effects and Potential Benefits

While direct evidence for citrulline’s impact on testosterone is lacking, the amino acid may offer indirect benefits that mimic some effects of increased testosterone. These include:

  1. Improved Exercise Performance: Citrulline has been shown to enhance exercise performance and reduce muscle soreness, effects often associated with higher testosterone levels.

  2. Enhanced Sexual Function: Some studies suggest that citrulline may improve erectile function and increase sexual activity in men with mild erectile dysfunction.

  3. Cardiovascular Health: Citrulline’s ability to increase NO production may contribute to better cardiovascular health, which can indirectly support overall hormonal balance.

Dosage and Safety Considerations

The dosage of citrulline used in various studies ranges widely, from 800 mg to 15 grams per day. Most research indicates that citrulline is generally safe and well-tolerated at these doses, with no significant adverse effects reported. Still the optimal dosage for any potential testosterone-related benefits remains unclear.

It’s crucial to note that while citrulline appears to be safe for most individuals, anyone considering supplementation should consult with a healthcare professional, especially those with pre-existing medical conditions or those taking medications.

The Need for Further Research

The current body of evidence regarding citrulline’s effect on testosterone levels is insufficient to draw definitive conclusions. Several key areas require further investigation:

  1. Direct Measurement of Testosterone: Future studies should focus on directly measuring testosterone levels in response to citrulline supplementation.

  2. Long-term Effects: Larger, long-term studies are needed to assess the potential cumulative effects of citrulline on testosterone levels and overall hormonal balance.

  3. Mechanism Elucidation: More research is required to understand the exact mechanisms by which citrulline might influence testosterone production, if any.

  4. Population-specific Studies: Investigations should explore citrulline’s effects on different populations, including healthy individuals, athletes, and those with hormonal imbalances.

Citrulline’s Other Health Benefits

While the evidence for citrulline’s impact on testosterone remains inconclusive, the amino acid has shown promise in other areas of health:

  1. Cardiovascular Health: Citrulline’s ability to increase NO production may contribute to improved blood pressure regulation and overall cardiovascular function.

  2. Exercise Performance: Some studies suggest that citrulline supplementation may enhance exercise performance, particularly in high-intensity or endurance activities.

  3. Immune Function: Preliminary research indicates that citrulline might play a role in supporting immune system function.

These potential benefits highlight the need for continued research into citrulline’s various physiological effects, even if its direct impact on testosterone levels remains unproven.

Key Takeaways

  • Current scientific evidence does not conclusively support citrulline’s ability to directly increase testosterone levels.
  • Citrulline may offer indirect benefits that mimic some effects of increased testosterone, such as improved exercise performance and sexual function.
  • More research is needed to fully understand citrulline’s potential impact on hormonal balance and overall health.
  • Citrulline appears to be safe for most individuals, but consultation with a healthcare professional is advised before starting supplementation.
  • The amino acid shows promise in other areas of health, particularly cardiovascular function and exercise performance.

In conclusion, while citrulline has garnered attention for its potential health benefits, its role in increasing testosterone levels remains unproven. The current evidence suggests that citrulline’s effects on blood flow and nitric oxide production may offer some health advantages, but these do not necessarily translate to increased testosterone production. As research continues, we may gain a clearer understanding of citrulline’s impact on hormonal balance and overall health. For now, individuals interested in citrulline supplementation should focus on its well-established benefits and consult with healthcare professionals for personalized advice.


  1. NCBI – Citrulline and Male Sexual Function
  2. NCBI – Safety and Efficacy of Citrulline

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