Does Tribulus Work?

Also known as puncture vine, tribulus is a yellow-flowered plant commonly sold as a dietary supplement. Most tribulus users purchase the product under the belief that it has a steroid-like anabolic effect or the ability to raise testosterone levels. In Western alternative medicine, tribulus is often used for muscle growth or the treatment of erectile dysfunction. While animal studies are encouraging, human clinical trials have failed to find a consistent testosterone-boosting effect from tribulus.

Strength Training

• Bodybuilders often use tribulus as a natural alternative to steroids. It has an appeal beyond anabolic steroids because it is associated with far fewer side effects and it is not legally restricted. However, controlled studies have not yet found that tribulus has notable anabolic effects.

  A 2000 study examined the effect of tribulus on hormone levels and overall strength. It failed to demonstrate any hormone-altering effects of the herb, but other studies have found that it may slightly increase testosterone levels. If tribulus has anabolic effects, they are minimal.

Erectile Dysfunction

• A 2002 study attempted to verify tribulus' traditional use as an aphrodisiac. It monitored sexual behavior in male rats given tribulus and found that even neutered rats displayed more sexual behavior after being given tribulus extract. The study determined that the results were "statistically significant" and warranted further investigation.

  In humans, no well-organized trials have yet investigated tribulus' effect on human sexuality. While researchers believe that it can alter the testerone-receptors in the brains of rats, the effect is only theoretical in humans. Some products combine tribulus with other sexual-enhancement herbs like yohimbe.

Post-Cycle Therapy

• Athletes and patients taking anabolic steroids may use tribulus in an attempt to minimize the unwanted side effects of hormone-affecting drugs. Tribulus' aphrodisiac and potentially androgenic effects may help athletes restore a normal hormone balance, but no studies have specifically addressed this topic.

  Tribulus is not associated with any known side effects, so many herbalists and sports-medicine experts consider it to be "worth a try." However, most scientific data has yielded inconsistent results regarding the plant's overall efficacy.