Tribulus terrestris (commonly known as puncture vine—the bane of bicycles in areas where it grows) has a long history of traditional medical use in China, India, and Greece. It was recommended as a treatment for female infertility, impotence, and low libido in both men and women, and to aid rejuvenation after long illness. The herb became widely known in the West when medal-winning Bulgarian Olympic athletes claimed that use of tribulus had contributed to their success. However, current evidence suggests that it does not enhance sports performance.

What Is Tribulus terrestris Used for Today?

Studies performed in Bulgaria are the primary source of most current health claims regarding tribulus. According to this research, tribulus increases levels of various hormones in the steroid family, including testosterone, DHEA, and estrogen, and for this reason improves sports performance, fertility in men and women, sexual function (again in men and women), and symptoms of menopause (such as hot flashes).7-11 Unfortunately, the design of these studies appears to fall far short of modern scientific standards, and there has not been any trustworthy scientific confirmation of these supposed benefits. One well-designed study failed to find that tribulus affects male sex hormone levels in young men.17

Other studies that are far too preliminary to prove anything at all are quoted as proving that tribulus is helpful for the treatment of angina, high cholesterol, diabetes, and muscle spasms, and for the prevention of kidney stones.1,13-16

A properly designed, though small, human study compared the effects of tribulus (3.21 mg per kilogram of body weight—for example, 292 mg daily for a 200-lb man) against placebo on body composition and endurance among 15 men engaged in resistance training.3 At the end of the 8-week study, the only significant difference between the treatment and placebo groups was that the placebo group showed greater gains in endurance!

Another double-blind, placebo-controlled study enrolled 22 athletes and followed them for five weeks.18 The dose used in this trial was fixed at 450 mg daily for all participants. No benefits were seen.

Dosage

Tribulus terrestris is usually taken at a dose ranging from about 85 to 250 mg 3 times daily with meals. Some tribulus products are standardized to provide 40% furostanol saponins and taken at a dose providing 115 mg of saponins 2 to 3 times daily.

Safety Issues

No significant adverse effects have been noted in any of the clinical trials or human research studies of tribulus. Animal studies performed in Bulgaria are said to have found the herb safe both in the short and long terms.9 However, it is not clear whether these studies were performed in such a way that their conclusions can be trusted.

Tribulus is known to have a toxic effect on sheep.4,5,6

Note: Women who are pregnant or nursing should not use any tribulus product. If the herb works as described, it might alter hormones in unsafe ways.