Nutrition

Natural Testosterone Boosters: Hope or Hazard?

Posted on by Daniel Chapelle
03
Nov

We know the extra one percents applied overtime can make a tremendous difference to one’s competitive success. In a sport like bodybuilding which is largely subjective; many athletes aim to seperate the distance between fellow competitors by taking their physiques to new heights; through training harder, eating smarter & recovering more efficiently.

In the quest to do so, it’s common for natural bodybuilders to explore supplements that can give them the edge; one of which are natural testosterone boosters. A group of supplements often comprising of herbs, amino acids, or minerals that claim to elevate endogenous testosterone levels, thereby promoting it’s anabolic effects.

Due to an individuals testosterone & it’s strong correlation with muscle mass, the theory is that elevating this hormone would result in better gains & improved recovery. In this article we explore whether these supplements translate into meaningful improvements in muscle mass and strength? And are there potential risks, such as contamination with banned substances, that natural athletes should be wary of?

Total Vs. Free Testosterone: It’s Not so Straight Forward

Before we dive into the common natural testosterone boosters & their relevant literature, it’s important to set some groundwork. Testosterone in the bloodstream exists in two primary forms:

  • Total Testosterone: This encompasses all testosterone in the blood, including both bound (to proteins like sex hormone-binding globulin [SHBG] and albumin) and unbound fractions.

  • Free Testosterone: This refers to the unbound fraction, which is biologically active and readily available to tissues.

While total testosterone provides an overall measure, free testosterone is often more indicative of the hormone’s biological activity, especially concerning muscle development and strength gains. This distinction is incredibly important as it provides better insight into what literature depicts with regards to it’s findings.

Evaluating Common Natural Testosterone Boosters

1. D-Aspartic Acid (DAA)

Mechanism of Action:
DAA is a non-essential amino acid found in the hypothalamus, pituitary gland, and testes. It is thought to stimulate the release of gonadotropin-releasing hormone (GnRH), leading to an increase in luteinizing hormone (LH), which in turn stimulates Leydig cells in the testes to produce testosterone (Topo et al., 2009).

Key Evidence:

  • In untrained men with low testosterone, 12 days of 3.12 g/day DAA supplementation increased total testosterone by 42% (Topo et al., 2009).

  • However, in trained men, Willoughby et al. (2013) found that 3 g/day DAA for 28 days did not increase total or free testosterone and had no effect on muscle strength or body composition.

Summary:
DAA may temporarily increase total testosterone in men with low levels, but it offers no ergogenic benefits for resistance-trained individuals with normal baseline T.

2. Tongkat Ali (Eurycoma longifolia)

Mechanism of Action:
Tongkat ali is believed to enhance testosterone through multiple mechanisms: increasing LH secretion, reducing cortisol, and inhibiting aromatase and SHBG activity. It may also improve mood and stress-related hypogonadism (Low et al., 2013; George et al., 2021).

Key Evidence:

  • In a 4-week trial, 200 mg/day of standardized Tongkat ali significantly increased total testosterone and decreased cortisol in moderately stressed men (Low et al., 2013).

  • A systematic review found consistent improvements in both total and free testosterone, especially in men with low T or under chronic stress (George et al., 2021).

Summary:
Tongkat ali may support increases in both total and free testosterone, particularly in stressed or hypogonadal populations, with modest improvements in strength outcomes when paired with training.

3. Fenugreek (Trigonella foenum-graecum)

Mechanism of Action:
Fenugreek seeds contain furostanolic saponins (e.g., protodioscin), which may inhibit 5α-reductase and aromatase enzymes, thereby reducing testosterone breakdown. Fenugreek may also reduce SHBG binding, thereby increasing free testosterone (Wilborn et al., 2010).

Key Evidence:

  • In a 56-day study, 500 mg/day fenugreek extract led to significant increases in free testosterone and reductions in body fat percentage in resistance-trained men (Poole et al., 2010).

  • Another study found that fenugreek suppressed aromatase and increased libido, although total testosterone remained unchanged (Wilborn et al., 2010).

  • A systematic review by Fathi et al. (2019) found that fenugreek supplementation was associated with a significant increase in total testosterone levels. However, the authors noted variability in study designs and dosages, & the need to standardised protocols in future research to confirm these findings.

Summary:
Fenugreek may not elevate total testosterone, but it consistently increases free testosterone, likely via SHBG modulation, and shows potential for improving strength and body composition with training. That said, the studies that depict these results may need a better standardisation in their design to strengthen the efficacy of these findings.

4. Ashwagandha (Withania somnifera)

Mechanism of Action:
Ashwagandha is an adaptogen that reduces chronic stress and cortisol levels, which may otherwise suppress the hypothalamic-pituitary-gonadal axis. It may also directly stimulate testosterone production in Leydig cells (Lopresti et al., 2019).

Key Evidence:

  • Wankhede et al. (2015) found that 600 mg/day of KSM-66 Ashwagandha in resistance-trained men over 8 weeks led to significant gains in muscle strength and size, with a 15% increase in total testosterone.

  • Lopresti et al. (2019) found that ashwagandha supplementation in stressed men led to significant increases in both total and free testosterone, alongside reduced perceived stress.

Summary:
Ashwagandha appears to elevate both total and free testosterone, particularly by lowering cortisol in stressed individuals, and supports strength and hypertrophy in trained subjects.

5. Fadogia Agrestis

Mechanism of Action (Proposed):
In rodent studies, Fadogia appears to stimulate LH release, increasing testicular testosterone production. However, it may also induce Leydig cell hypertrophy and testicular toxicity at high doses (no human data yet available).

Key Evidence:

  • No published human trials to date. All available data are preclinical or anecdotal.

Summary:
Fadogia is widely marketed but lacks any human clinical evidence. Potential toxicity in animals suggests caution, especially for athletes subject to doping controls.

6. Shilajit

Mechanism of Action:
Shilajit is a complex mineral pitch containing fulvic acid and dibenzo-α-pyrones, which may act on the hypothalamus-pituitary axis and testicular steroidogenesis, possibly improving mitochondrial function and testosterone biosynthesis (Pandit et al., 2016).

Key Evidence:

  • In a double-blind RCT, 250 mg/day of purified Shilajit for 90 days increased total testosterone by 20% and free testosterone by 19% in healthy middle-aged men (Pandit et al., 2016).

  • Another study by Ziegenfuss et al. (2016) also observed similar increases in testosterone with shilajit supplementation.

Summary:
Shilajit may enhance both total and free testosterone in older men, though no studies to date have evaluated its effect in trained athletes or in conjunction with resistance training.

Systematic Reviews and Meta-Analyses

Over the past decade, the scientific community has undertaken numerous systematic reviews and meta-analyses to assess the effectiveness of natural testosterone boosters, particularly concerning their impact on serum testosterone levels, muscle mass, and strength in humans.

1. Morgado et al. (2024): Comprehensive Evaluation of Testosterone Boosters

In a systematic review published in the International Journal of Impotence Research, Morgado et al. (2024) analyzed 50 studies focusing on various natural testosterone boosters. The review found that while some supplements, such as fenugreek, ashwagandha, and tongkat ali, showed modest increases in testosterone levels, the overall evidence was inconsistent. Notably, the increases in testosterone were often within the physiological range and did not consistently translate into significant improvements in muscle mass or strength. The authors concluded that the efficacy of these supplements remains uncertain, especially in healthy, resistance-trained individuals.

2. Tsampoukas et al. (2021): Assessment of Herbal Supplements

Tsampoukas et al. (2021) reviewed the effects of various herbal supplements, including ashwagandha and tongkat ali, on testosterone levels. Their findings indicated that while some herbs might offer benefits in specific populations (e.g., individuals with low baseline testosterone), the evidence supporting their use in enhancing muscle mass and strength in healthy individuals was limited. The review emphasised the importance of rigorous clinical trials to establish the safety and efficacy of these supplements.

The Physiological Range: Dr Stuart Phillips Perspective

In healthy adult males, serum total testosterone typically ranges between 300 to 1,000 ng/dL (10.4-34.7 nmol/L), according to reference ranges established by most clinical labs and endorsed by the Endocrine Society.

  • Free testosterone, the bioavailable portion not bound to sex hormone-binding globulin (SHBG), generally falls between 5-21 ng/dL (0.17-0.73 nmol/L).

  • These values can vary slightly by lab, age, and assay method.

It’s important to note that even within this range, a man with 350 ng/dL and one with 900 ng/dL are both considered “eugonadal” (normal T), and the clinical implications of being at the higher versus lower end are still debated, especially for resistance-trained individuals.

Dr. Stuart Phillips, a leading researcher in skeletal muscle physiology and hypertrophy, has consistently argued that small increases in testosterone within the normal range are unlikely to result in meaningful increases in lean mass or strength.

His position is consistent with several findings in the literature:

  • Bhasin et al. (2001) demonstrated that only supraphysiological testosterone doses (e.g., 600 mg/week) which elevate levels well above 2,500 ng/dL produce robust increases in muscle size and strength.

  • In natural settings, even modest increases of 100-300 ng/dL (which many supplements claim to achieve) have no reliably measurable effects on strength, lean body mass, or muscle protein synthesis (Phillips, personal communications; Bhasin et al., 2001).

  • Free testosterone may matter more than total T, but increases still need to be substantial and sustained and even then, resistance training is the overriding stimulus for growth.

  • For natural bodybuilders, trying to “optimise” testosterone within the normal range may offer diminishing returns, especially if it distracts from training consistency, sleep, and diet quality.

Understanding the Risks of “Natural” Test Boosters

While natural testosterone boosters are often marketed as safe and legal alternatives to performance enhancing drugs, a substantial body of evidence suggests that some over-the-counter supplements may be contaminated with banned substances. 

Scientific studies & statistical analyses have shown that supplement contamination is a widespread issue:

  • Kozhuharov et al. (2022) conducted a systematic review of 50 studies analysing 3,132 supplements. They found that 28% contained undeclared substances, including anabolic steroids and banned stimulants like sibutramine. These substances were often not listed on the product label, posing a high risk of unintentional doping.

  • Costa et al. (2019) highlighted that common contaminants in sports supplements include anabolic agents, stimulants, heavy metals, and pharmaceutical drugs. These findings were based on data from the Rapid Alert System for Food and Feed (RASFF) and global regulatory bodies.

  • Mathews (2017) reported similar concerns in the U.S., noting that muscle-building and fat-loss supplements are the most likely to be contaminated. The study emphasised that athletes are frequently unaware of these risks and may unknowingly ingest prohibited substances.

  • Lauritzen (2022) analysed 18 years of doping control data from Anti-Doping Norway. The study found that 26% of analytical anti-doping rule violations (ADRVs) involved athletes who claimed supplement contamination. In roughly half the cases, these claims were validated, demonstrating how real and impactful this issue can be for clean athletes.

  • A 2025 report from Sport Integrity Australia found that over 35% of sports supplements available in the Australian market contained WADA-prohibited substances not disclosed on the labels. This underscores the risk for Australian athletes not using certified products.

Mitigating Risk: Best Practices for Athletes

To reduce the risk of inadvertent risk of doping:

  • Use only third-party certified supplements, such as those tested by Informed-Sport, NSF Certified for Sport, or HASTA. These certifications verify that the product is free of banned substances under WADA regulations.

  • Avoid proprietary blends or unverified online brands, particularly those marketed for testosterone boosting, muscle gain, or fat loss.

  • Keep documentation and batch numbers of all supplements used, which can aid in investigations if an anti-doping violation occurs.

  • Seek guidance from a qualified sports nutritionist or physician before adding any supplement to your regimen especially during contest prep or competition phases.

Final Verdict: Hope or Hazard?

While the allure of natural testosterone boosters is strong, especially for those seeking legal performance enhancements, the current body of evidence suggests limited efficacy for muscle growth and strength gains in healthy, resistance-trained individuals. Additionally the posed risks associated with supplement contamination and health side effects cannot be overlooked.

For natural bodybuilders aiming for long-term progress, focusing on foundational elements remains paramount such as following a structured resistance training program with emphasis on progressive overload & volume management. Optimal nutrition with an emphasis on adequate calorie, protein, carbohydrate & fat intake alongside sufficient micronutrient diversity. Lastly, quality recovery through sufficient sleep & stress management strategies.

Emphasising these evidence-based strategies offers a reliable path to achieving bodybuilding goals without the uncertainties & risks associated with natural testosterone boosters.

References

Bhasin, S., Woodhouse, L., Casaburi, R., Singh, A. B., Bhasin, D., Berman, N., & Storer, T. W. (2001). Testosterone dose–response relationships in healthy young men. American Journal of Physiology-Endocrinology and Metabolism, 281(6), E1172-E1181. https://doi.org/10.1152/ajpendo.2001.281.6.E1172

George, A., Henkel, R. R., & Khatri, D. K. (2021). Eurycoma longifolia (Tongkat Ali) as a potential herbal supplement for physically active male and female populations: A systematic review. Complementary Therapies in Clinical Practice, 45, 101486. https://doi.org/10.1016/j.ctcp.2021.101486

Lopresti, A. L., Smith, S. J., Malvi, H., & Kodgule, R. (2019). An investigation into the stress-relieving and pharmacological actions of an ashwagandha (Withania somnifera) extract: A randomized, double-blind, placebo-controlled study. Medicine, 98(37), e17186. https://doi.org/10.1097/MD.0000000000017186

Low, B. S., Choi, S. B., Abdul Wahab, H., Das, P. K., Chan, K. L., & Yam, M. F. (2013). Eurycoma longifolia upregulates osteoprotegerin gene expression in androgen-deficient osteoporosis rat model. International Journal of Molecular Sciences, 14(3), 4856-4870. https://doi.org/10.3390/ijms14034856

Pandit, S., Chauhan, N. S., Dixit, V. K. (2016). Effect of Shilajit on testosterone levels and semen parameters in infertile men. Andrologia, 48(6), 570-575. https://doi.org/10.1111/and.12482

Poole, C., Bushey, B., Foster, C., Campbell, B., Willoughby, D. S., Kreider, R., … & Taylor, L. (2010). The effects of a commercially available botanical supplement on strength, body composition, power output, and hormonal profiles in resistance-trained males. Journal of the International Society of Sports Nutrition, 7(1), 34. https://doi.org/10.1186/1550-2783-7-34

Topo, E., Soricelli, A., D’Aniello, A., Ronsini, S., & D’Aniello, G. (2009). The role and molecular mechanism of D-aspartic acid in the release and synthesis of LH and testosterone in humans and rats. Reproductive Biology and Endocrinology, 7, 120. https://doi.org/10.1186/1477-7827-7-120

Wankhede, S., Langade, D., Joshi, K., Sinha, S. R., & Bhattacharyya, S. (2015). Examining the effect of Withania somnifera supplementation on muscle strength and recovery: A randomized controlled trial. Journal of the International Society of Sports Nutrition, 12, 43. https://doi.org/10.1186/s12970-015-0104-9

Wilborn, C. D., Taylor, L. W., Poole, C. N., Foster, C. A., Willoughby, D. S., & Kreider, R. B. (2010). Effects of a purported aromatase and 5α-reductase inhibitor on hormone profiles in college-age men. International Journal of Sport Nutrition and Exercise Metabolism, 20(6), 457-465. https://doi.org/10.1123/ijsnem.20.6.457

Willoughby, D. S., Spillane, M., & Schwarz, N. (2013). Effects of 28 days of resistance exercise and consuming a commercially available pre-workout supplement, D-aspartic acid, on body composition, muscle strength, and serum hormones in resistance-trained men. Nutrition Research, 33(10), 803-810. https://doi.org/10.1016/j.nutres.2013.07.014

Ziegenfuss, T. N., Hofheins, J. E., Mendel, R. W., Landis, J., & Anderson, R. A. (2016). Effects of a water-soluble extract of shilajit on testosterone levels in healthy volunteers: A randomized, double-blind, placebo-controlled study. Journal of Ethnopharmacology, 194, 1124-1129. https://doi.org/10.1016/j.jep.2016.11.045

Bhasin, S., Woodhouse, L., Casaburi, R., Singh, A. B., Bhasin, D., Berman, N., Chen, X., Yarasheski, K. E., Magliano, L., Dzekov, C., Dzekov, J., Bross, R., Phillips, J., Sinha-Hikim, I., Shen, R., & Storer, T. W. (2001). Testosterone dose-response relationships in healthy young men. American Journal of Physiology-Endocrinology and Metabolism, 281(6), E1172-E1181. https://doi.org/10.1152/ajpendo.2001.281.6.E1172

Daniel Chapelle

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