How we rate
“Strong” = several concordant meta-analyses or systematic reviews. “Moderate” = one synthesis, or several controlled trials. “Limited” = early trials only. The rating is about the quality of the studies, not about how useful the supplement is.
Tribulus terrestris
Sold as a testosterone booster in bodybuilding, but several trials in young men or trained athletes show no increase in testosterone or strength gains. Other literature on sexual function in men and women tells a different story.
Benefits
- In premenopausal and postmenopausal women suffering from hypoactive sexual desire disorder, significantly improves the female sexual function score (desire, arousal, lubrication) compared to placebo, in four double-blind randomized trials of 90 to 120 days bringing together 40 to 67 participants each
- In 180 men suffering from mild to moderate erectile dysfunction, 750 mg per day for 12 weeks significantly improve the erectile function score and sexual desire compared to placebo, with no serious adverse effect
- In 70 elderly men with late-onset hypogonadism and erectile dysfunction, 3 months of treatment significantly raise total testosterone and improve sexual function, without worsening associated urinary disorders
- In infertile men, improves certain sperm parameters (count, motility, morphology) in 6 out of 7 clinical trials identified by a 2019 systematic review
Precautions
Sold for testosterone, Tribulus terrestris does not increase it in healthy young men: 4 weeks of supplementation do not modify testosterone, androstenedione or LH in 21 men (2005). In trained athletes, it also does not change strength or body composition: no difference from placebo on weight or fat mass after 8 weeks (15 men, 2000), nor on strength and lean mass after 5 weeks in 22 elite rugby players (2007) — where the urinary testosterone/epitestosterone ratio also remains unchanged, thus carrying no risk of a positive doping test. Two trials in CrossFit athletes (30 participants each, 6 weeks, 770 mg/day) also show no significant improvement in performance, body composition or inflammation markers. In 30 men over 40 years old, erectile function improves just as much with Tribulus as with placebo after 30 days: no significant difference between the two groups. A 2016 systematic review moreover concludes that evidence for an androgenic effect remains inconclusive. The hormonal signal is sometimes even reversed: in women treated for 90 days, DHEA increases but total and free testosterone decrease. The safety profile is generally good in trials, with mostly digestive adverse effects. Medical advice is necessary in the event of ongoing hormone therapy or diagnosed hypogonadism, one of the rare populations where an effect on testosterone has precisely been measured.
Recommended dosage
Trials showing an effect on sexual function most often use 750 mg per day (250 mg three times a day), over durations of 90 to 120 days for women and 12 weeks for men with erectile dysfunction — one trial in hypogonadal elderly men lasted up to 3 months. Trials finding no effect on testosterone or strength used 450 to 800 mg per day for only 4 to 8 weeks: duration matters at least as much as dose.
How to take it
- Dose: 750 mg per day, or 250 mg three times per day, in most positive trials on sexual function.
- How long: 90 to 120 days in women, 12 weeks in men. In men, short trials (4 to 8 weeks) find nothing on testosterone.
- For sports: no strength, no lean mass, and no extra performance in rugby players, weightlifters, or CrossFit practitioners, apart from an increase on the leg press in one trial.
- Anti-doping control: in rugby players, 450 mg per day for 5 weeks did not change the urinary testosterone/epitestosterone ratio.
Did you know?
Contrary to claims, Tribulus terrestris does not increase testosterone levels or muscle mass in healthy young men or trained athletes.
What the studies say
This systematic review synthesized clinical trials evaluating the effect of Tribulus terrestris on sperm parameters in men suffering from idiopathic infertility. Out of 7 included articles, 6 reported that the consumption of Tribulus terrestris L. improved some or all semen parameters, notably count, motility, and morphology. The review concludes that Tribulus terrestris can generally lead to an improvement in sperm parameters.
Sanagoo S, Sadeghzadeh Oskouei B, Gassab Abdollahi N, Salehi-Pourmehr H, Hazhir N, Farshbaf-Khalili A. — Complementary therapies in medicine (2019) — View the source study
For information only: not a substitute for medical advice. Dietary supplements are not a replacement for a varied, balanced diet. Learn more