Tribulus terrestris (also called puncturevine or caltrops) is an herb derived from a Mediterranean plant that bears a spine-covered fruit. The active components—the leaf, fruit, and root—have medicinal properties. The active ingredient in Tribulus—protodioscin (a steroidal saponin)—used in dietary supplements is purported to increase levels of hormones, including testosterone, luteinizing hormone, dehydroepiandrosterone (DHEA), and dihydrotestosterone, which explains why it is used to enhance muscle strength and athletic performance. It has also been used as an antidote for male impotence and for other uses. Tribulus terrestris is touted as being an indirect testosterone “booster,” and while it is not a drug, its mechanism of action remains unclear.

There is insufficient data on whether tribulus terrestris increases levels of testosterone in humans, and no scientific evidence shows that taking Tribulus terretris enhances strength or athletic performance. Although there are chemical-structure similarities to DHEA, no literature indicates it will result in a positive test for steroids. Since the findings on T. terrestris are inconclusive, we discourage the use of this and comparable products. Read multi-ingredient product labels carefully, too, as it is sometimes combined with other ingredients. It is important to note that contamination of nutritional supplements with prohibited substances has been reported, so you may want to read the FDA’s News Release on “Tainted products marketed as dietary supplements potentially dangerous."