What is Tribulus Terrestris?
Tribulus Terrestris, also known as puncture vine, is a weedy, tap-rooted plant native to the Mediterranean region. This plant belongs to the caltrop family and it grows in the warm and tropical regions of southern Europe and southern Asia. The plant has also naturalized to America and Australia and is considered an invasive species in both areas. It is considered to be an aggressive species of weed due to its spiked, hard fruit that can injure bare-footed pedestrians and puncture bicycle tires.
Properties of Tribulus Terrestris
Tribulus Terrestris, TT, has many different components like steroidal saponins, flavonoids, glycosides, phytosterols, tannins, terpenoids, amide derivatives, amino acids, and proteins that have various biological functions. Among all alkaloids isolated from TT, two of them have been found to cause limb paresis in sheep who consume TT. Steroidal saponins are the most important phytochemical with regards to the medical use of TT.
Uses of Tribulus Terrestris
Tribulus Terrestris is a fruit-producing plant that is used for its medicinal properties. Leaves, fruit, and root of the plant have been long used as a medicine in ancient Chinese medicine, Ayurvedic treatment, and traditional medicine of south-east Asia.
In Ayurveda, Tribulus Terrestris is used for the treatment of decreased libido, sexual impotence, erectile dysfunction, and infertility. In Chinese medicine, it is used for the treatment of several eye disorders and skin pruritus, along with headaches and vertigo. It can also be used for mammary duct blockage. In Sudan, it is used for treatment for multiple inflammatory disorders, and in Pakistan, it is used as a diuretic. There are many uses for TT in its native countries, however, the common use for it is as a male performance-enhancing supplement.
However, now Tribulus Terrestris is sold as an herbal supplement for male virility, bodybuilding, and general vitality. Companies producing the supplements claim that TT can increase testosterone levels and boost libido. It is often advertised as a Testosterone booster and an Estrogen blocker. It is also used for muscle gain, with companies guaranteeing results in 5-28 days.
It is also believed to have anti-inflammatory and anti-aging effects which have been studied widely.
Scientific evidence of TT’s pharmacological activities
TT, in herbal medicine, has been linked with increased levels of testosterone and the treatment of several sexual disorders. Recent studies have aimed to study this medicinal capability of TT’s fruit as it is widely used for this purpose alone.
In several in vitro studies performed in Iran and Korea, TT extract showed positive results on sperm motility and viability. Hence indicating that TT can treat spermatozoal pathologies. Preclinical studies performed on adult, male Swiss albino mice showed an increase in testosterone and improved spermatozoal viability.
Furthermore, rats given TT supplementation showed a great increase in testosterone levels when compared to the control group in multiple studies performed in Iran and China.
In another study performed in Bulgaria, TT extract was given to castrated rats, and they showed improved sexual behavior.
Two double-blind, randomized, place-controlled clinical trials were conducted for erectile dysfunction by Kamenov et al. and Santos et al. respectively. Kamenov’s study involved the intervention group being given 250mg of dry extract and showed great improvement in erection and libido compared to the placebo group. However, Santos’s study showed no significant results when compared to the placebo group. It is important to note that although Santos’s subjects were given 400mg of extract, the origin of the plant or method of extraction wasn’t specified and could be the reason for the opposite results.
Two other clinical trials supported the claims of Kamenov, as these studies also showed benefits of TT extract on muscle power and testosterone levels.
The mechanism of action of TT on testosterone is believed to be due to steroidal saponins of TT. This saponin affects the LH and FSH levels, along with eNOS activation resulting in increased testosterone and vasodilation leading to penile erection.
Since this plant is proven to increase testosterone levels, it also results in the hypertrophy or increased size of skeletal muscles, showing anabolic properties of the plant. Since the initial testing in Bulgaria confirming the benefits of Tribulus Terrestris on testosterone levels and hence, the muscle development, many Bulgarian athletes have been using it for its anabolic properties. This is considered as, ‘doping’ and is frowned upon in sports.
However, in a study performed on rugby players, it was found that the ‘increased muscle mass in 5-28 days’ claim of multiple brands is a hoax. This randomized clinical trial showed no differences between intervention and placebo group when it came to muscle gain. Interestingly, when the athletes’ urine was checked for testosterone/epitestosterone ratio which tells us if an athlete is doping or not, the urine came clean. This shows that the use of TT may produce a negative doping result. However, similar studies where a higher dose of TT was used showed urine positive for doping. Further studies need to be performed for a conclusive answer on if a person taking Tribulus Terrestris will pass or fail the doping test.
In a study published in the Korean Society for Biotechnology and Bioengineering Journal, researchers evaluated the anti-aging and skin volume augmentation effect of a Tribulus Terrestris fruit extract cream on their subject and the results were great. The subjects’ skin showed a 35% and a 25% increase in procollagen I and elastin respectively. Since aging is associated with loss of elasticity and sagginess associated with loss of procollagen I and elastin, an increase in these implies anti-aging effects of TT. However, further studies need to be performed for Tribulus Terrestris fruit to be used as a skincare product.
Tribulus Terrestris Toxicology
Toxic doses of TT are associated with symptoms like tremor, sleeplessness, nausea or vomiting, excitement, mydriasis, dyspnea and ataxia, and hyperactivity. Furthermore, many case reports have been published indicating the nephrotoxic effects of Tribulus Terrestris.
Exact toxicologic components of TT are not known but the US National Library of Medicine has identified seven possible toxicological components. Harmine, an alkaloid component of TT, is the only one with a complete toxicological profile.
Rogerson, Shane et al. “The effect of five weeks of Tribulus Terrestris supplementation on muscle strength and body composition during preseason training in elite rugby league players.” Journal of strength and conditioning research vol. 21,2 (2007): 348-53. doi:10.1519/R-18395.1
Ștefănescu, Ruxandra et al. “A Comprehensive Review of the Phytochemical, Pharmacological, and Toxicological Properties of Tribulus Terrestris L.” Biomolecules vol. 10,5 752. 12 May. 2020, doi:10.3390/biom10050752
Zhu, Wenyi et al. “A review of traditional pharmacological uses, phytochemistry, and pharmacological activities of Tribulus Terrestris.” Chemistry Central journal vol. 11,1 60. 11 Jul. 2017, doi:10.1186/s13065-017-0289-x