There isn't much science done behind this using supplement. Anecdotal reports suggest that many people use this herb for treating impotence and for body building.
As for using this herb in sport nutrition to improve athletic performance and for body building, clinical studies didn't show much benefit.
Marketed as an aphrodisiac and for treating erectile dysfunction, many products contain multiple ingredients such as yohimbe (yohimbine), catuaba, horny goat weed (epimedium), maca, ginkgo, L-arginine, ginseng, damiana, muira puama, DHEA and vitamins and minerals.
By the way, the lack of evidence of effectiveness does not mean that it does not work. It means that there are no quality research studies done to prove whether it works or not.
Increasing Testosterone Blood Levels
Results from animal and human studies are mixed. Some studies show that it increases blood testosterone levels and others do not.
For example, one of the more recent study published by Fiziol in 2009 showed that taking 1 capsule 3 times daily for 20 days resulted in increased blood testosterone levels for the first 10 days. Afterwards, the levels did not increase any further.
Erectile Dysfunction (ED) / Impotence
Animal studies by K. Gauthaman (January 2008) showed that Tribulus terrestris increases testosterone levels, thus increasing sex drive in primates, rabbits and rats. The conclusion was that the herb "may be useful in mild to moderate cases of ED."
However, V.K. Neychev (October 2005) conducted a study in young men and the results showed that, "Tribulus terrestris steroid saponins possess neither direct nor indirect androgen-increasing properties."
Hence there are conflicting results. Most studies done in animals clearly show an increase in testosterone and other sex hormones along with an aphrodisiac benefit but the studies in human showed no such benefits.
Aphrodisiac / Low Libido / Increase Sex Drive
Animal studies by K. Gauthaman (January 2008) concluded that Tribulis terrestris increases testosterone levels, thus increasing sex drive in primates, rabbits and rats.
As well, P.G. Adaikan (January 2000) suggested that, "The enhanced relaxant effect observed is probably due to increase in the release of nitric oxide from the endothelium and nerve endings, which may account for its claims as an aphrodisiac."
We were unable to locate any clinical research studies to show if Tribulus terrestris would be useful in increasing libido in humans.
For other natural remedies that are used to increase sex drive,click here.
Increase Sperm Production
Rats given this herb producted more sperms. The testosterone level was not affected. Experts believe that this herb was able stimulate sperm production through another mechanism other than by increasing testosterone levels.
Angina Pectoris (Chest Pain)
Tribulus terrestris seems to enhance blood flow to the coronary arteries and this will help patients suffering from angina as reported by B. Wang (February 1990).
Diabetes / Diabetes Prevention
A. Amin et al. (November 2006) showed that Tribulus terrestris had an protective effect on rats with diabetes. Several other researchers independently demonstrated that Tribulus terrestris significantly lowered blood glucose in rats.
Studies done in a lab setting on breast cancer cell tissues showed that T. terrestris causes the cells to shrink and the nucleus to contract.
Enhancing Athletic Performance - Most likely not effective
Multiple research studies in human shows that Tribulus terrestris does not enhance athletic performance. The best designed study by S. Rogerson et al. (May 2007) concluded that, "T. terrestris did not produce the large gains in strength or lean muscle mass that many manufacturers claim can be experienced within 5-28 days." and, "... it is also reassuring that taking T. terrestris does not put an athlete at risk of testing positive based on the World Anti-Doping Agency's [requirements]..."
Other research studies showed the same negative results.
As well G.A. Brown et al. (September 2000) showed that combining herbal extracts (such as those that includes Tribulus terrestris) designed to increase testosterone levels did "not result in increased serum testosterone concentrations, reduce the estrogenic effect of androstenedione, and does not augment the adaptations to resistance training."
Neychev et al. (October 2005) discovered that, "Testosterone, androstenedione and luteinizing hormone levels in the serum were measured 24 h before supplementation (clear probe), and at 24, 72, 240, 408 and 576 h from the beginning of the supplementation. There was no significant difference between ... [the] supplemented groups and controls in the serum testosterone ."
The parts of the plant used are the leaf, fruit and root. It is a flowering plant located in southern Europe, southern Asia, throughout Africa and in northern Australia.
The component that is suspected to be responsible for Tribulus terrestris benefits is saponins (a type of steroid glycosides), specifically protodioscin. It is suggested from animal studies that it increases testosterone, luteinizing hormone (LH) and DHEA (dehydroepiandrosterone) levels, leading to an increase in sex drive.
In animal studies, this herbal supplement increases testosterone levels which lead to increased sex drive. It is suspected that the herb might increase sex drive through the synergy of increased testosterone level and the increased release of nitric oxide (necessary for achieving an erection).
In many studies done in humans, researchers found that Tribulus terrestris does not increase testosterone levels sufficiently to explain its benefit as an aphrodisiac. One researcher suggested that there might be a different mechanism of action that has not been discovered yet.
The natural supplement does seem to dilate the blood vessels in the heart to help with angina (chest pain) and it might therefore also increase the blood flow to the penis to support a stronger erection. This is speculation until further research is done. Because of the weakness of the results from good research studies done on human subjects, we are unable to assign more than a one-leaf rating on this herb for its use in treating erectile dysfunction.
A. Adimoelja (2000) commented that, "Protodioscin is a phytochemical agent derived from Tribulus terrestris L plant, which has been clinically proven to improve sexual desire and enhance erection via the conversion of protodioscine to DHEA..."
aphrodisiac / low libido / increase sex drive
chest pain (angina pectoris)
chronic fatigue syndrome
coughs and sore throat
diuretic (to promote water loss)
eczema (atopic dermatitis)
enhancing athletic performance
erectile dysfunction / impotence
high blood pressure (hypertension)
high cholesterol (hypercholesterolemia)
increase muscle mass
urinary problems / painful urination
There are few reported side effects from using this herb. The herb might lower blood pressure and blood sugar levels. It can also increase the skin's sensitivity to sun exposure.
Safety - There are no reported health risks from using Tribulus terrestris. In appropriate doses, Tribulus terrestris is probably safe to use.
Pregnancy & Lactation - One research study in animals indicates that Tribulis terrestris might affect the developing fetus. Avoid using. There is no information on the safety of using Tribulus terrestris when breastfeeding. Avoid using.
Diabetic Medication / Diabetes - theoretical
Several research studies showed that the herb lowers blood sugar level in rats.
Monitor your glucose levels when starting or stopping this herb.
Prostate Cancer - theoretical
The herb might, in theory, worsen individuals with existing prostate cancer.
Benign Prostatic Hypertrophy (BPH) - theoretical
The herb might, in theory, cause prostate enlargement. One research showed that it increased the weight of the prostate gland in rats.
Doses of 250 mg daily have been used in research studies for enhancement in athletic performance.
There is no information on optimum dosage for the herb so start with a low dosage and increase gradually.
Buy the standardized extract to ensure you get what you pay for. It should be standardized to the active ingredient saponins when possible. (Typical standardized extract contains between 20% to 40% saponins such as furostanol.)
Selected References for Tribulus Terrestris Picture of Tribulus terrestris by Forest & Kim Starr
Updated: March 24, 2010