Part one of a two-part series on Tribulus terrestris, one of the most popular sport and sexual enhancement supplements on the market. The history, research and safety are looked at in scrutinizing detail.
This is part one of a two-part series highlighting one of the most famous dietary supplements on the market and the research behind the herb.
Principal Proposed Use
Sports Performance Enhancement1
Other Proposed Uses
Sexual Dysfunction (in Men and Women)2 3
History
Tribulus terrestris (tribulus), commonly known as puncture vine, has a long history of traditional medical use in China, India and Greece.4 It was recommended as a treatment for impotence and low libido (primarily in men) and also used to aid rejuvenation after long illness. The herb became widely known in the West when medal-winning Bulgarian Olympic athletes (mostly strength athletes) claimed that the use of tribulus had contributed to their success.5 Tribulus hit the supplement market approximately 15 years ago and has continually waxed and waned over the past years with strength athletes, and those looking for increased libido. What is most interesting is that in some cultures where the tribulus plant grows, the natives used to cover the vine with poison and then set the thorn-covered plant on trails that their enemies would use, hoping to inject the poison into them.6
Science Behind the Claims
Studies performed in Bulgaria are the primary source of most current health claims found in the lay literature regarding tribulus. Unfortunately, these studies have not been released to the general scientific community by the research institutes and companies in Eastern Europe, who reportedly conducted the research. Only the abstracts are available in English for the western world. According to this research, the supposed active components, furostanol saponins, cause their androgenic effects via the conversion of protodioscine to DHEA (De-Hydro-Epi-Androsterone)7, which can then be converted into testosterone, androstenedione and luteinizing hormone. Through this increase in sex hormones, tribulus supposedly improves sports performance, fertility and sexual function in men.8 9 10 11
Real Science Behind the Herb
Tribulus does have a small volume of literature that has been done on the herb by reputable laboratories. Both human and animal tests have been performed with isolation of the various components of the herb available for analysis. Interestingly, the herb in several animal model tests provided results that would suggest possible anabolic and spermatogenic behavior; however these have not materialized in human trials.
The best designed and most recent clinical human study compared the effects of tribulus (3.21 milligrams per kilogram of body weight) against placebo on body composition and endurance among 15 men engaged in resistance training.12 At the end of the 8-week randomized controlled clinical study, the only significant difference between the treatment and placebo groups was that the placebo group showed greater gains in endurance. The researchers came to the conclusion that “supplementation with tribulus does not enhance body composition or exercise performance in resistance-trained males.”
Recently, another randomized controlled clinical trial was accepted by The Journal of Ethnopharmacology from a Bulgarian lab of biochemistry that used 21 untrained healthy young males. The subjects were assigned to consume 20 mg and then 10 mg/kg body weight per day of Tribulus terrestris extract, respectively, separated into three daily intakes for four weeks. Testosterone, androstenedione and luteinizing hormone levels in the serum were measured 24 hours before supplementation (clear probe), and at 24, 72, 240, 408 and 576 hours from the beginning of the supplementation. The study showed no significant changes in the measured hormones. The researchers concluded in this way: “The findings in the current study anticipate that Tribulus terrestris possess neither direct nor indirect androgen-increasing properties.”13
As a result, research on strength training appears to be in the early stages with some human trials showing no clear-cut answer. Tune in next time for part two, which will cover the sexual function studies, safety issues and the final conclusion.
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1 http://www.bodybuilding.com/store/trib.html
2 http://www.raysahelian.com/tribulus.html
3 http://www.ayurvedicherbsdirect.com/tribulus-p-6.html
4 K. Gauthaman, P.G. Adaikan / Journal of Ethnopharmacology 96 (2005) 127–132
5 Bucci R. Luke. Am J Clin Nutr 2000; 72(suppl):624S–36S
6 Watt and Breyer-Brandwijk 1962 Historical Account
7 Adimoelja A. Phytochemicals and the breakthrough of traditional herbs in the management of sexual dysfunctions. Int J Androl. [abstract] 2000;23:82,84.
8 Kumanov F, Bozadzhieva E, Andreeva M, et al. Clinical trial of the drug "Tribestan." Savr Med. 1982;4:211-215.
9 Protich M, Tsvetkov D, Nalbanski B, et al. Clinical trial of the preparation Tribestan in infertile men. Akush Ginekol. 1983;22(4):326-329.
10 Viktorov IV, Kaloyanov AL, Lilov L, et al. Clinical investigation on Tribestan in males with disorders in the sexual function. Med-Biol Inf. 1982.
11 Zarkova S. Tribestan: Experimental and Clinical Investigations. Chemical Pharmaceutical Research Institute, Sofia, 1983.
12 Antonio J, Uelmen J, Rodriguez R, et al. The effects of Tribulus terrestris on body composition and exercise performance in resistance-trained males. Int J Sport Nutr Exerc Metab. 2000;10:208,215.
13 V.K. Neychev, V.I. Mitev. Journal of Ethnopharmacology, 101 (2005) 319–323
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Jessica Kim – A clinical nutritionist and aspiring dietician, Jessica spends most of her time doing rounds as a nutritionist in a hospital setting. Her passion for writing and health translate into a unique clinical perspective on health topics. Jessica has no problem pointing out where fitness enthusiasts take a single research study to the extreme, by reminding us of sound clinical advice! Jessica can be reached at jessicakim@mklaboratory.com