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Professor Jose Antonio, Department of Health
and Exercise Sciences, University of Delaware
- Tribulus terrestris is an herbal
preparation also known as puncture vine.
- It is used to augment baseline concentrations of plasma
testosterone.
- There is no standard recommended daily dose.
- There are no studies that have demonstrated that tribulus by
itself can affect plasma testosterone concentrations in humans.
- Tribulus is typically sold in capsules as an extract
standardized to a given level of saponins and protodyosin, the
“active” ingredients.
- Tribulus is a legal substance and its use is permitted by
sports governing bodies.
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Name
Tribulus terrestris (Tribulus, puncture vine)
Description
Tribulus terrestris has been used for centuries in Europe to treat
impotence; however, it has recently been touted as an anabolic agent to be
used by bodybuilders.
Usage
Tribulus purportedly enhances plasma testosterone concentrations; this
effect should theoretically enhance muscle protein accretion (i.e., an
anabolic muscle gain effect).
Prevalence
There are no current data on the prevalence or incidence of use.
Chemical Mechanism
The mechanisms underlying the alleged effects of tribulus have yet to be
demonstrated. At this point, there are no peer-reviewed studies that have
examined whether this herb can increase plasma testosterone.
Clinical Evidence
A placebo-controlled, double-blind study published in the International
Journal of Sport Nutrition and Exercise Metabolism examined the
effects of tribulus supplementation in a group of resistance-trained men.
The dose ingested was 3.21 mg per kg body weight daily for eight weeks.
Each subject participated in a heavy resistance-training program. The
investigators found no changes in body weight, percentage fat, total body
water, dietary intake, or mood states in either group. Thus, in this
limited sample of resistance-trained men, the consumption of tribulus
daily for eight weeks had no ergogenic effect.
Scientific Research
There is animal data that is of interest. Work by Dimitrov et al. found
that a tribulus-containing preparation increased plasma testosterone
levels in rams. This occurred supposedly via an increase in luteinizing
hormone. However, for the most part, the claims made by supplement
companies are not supported by peer-reviewed studies of any sort.
Administration
Tribulus is ingested orally in capsule form.
Dosage
Due to the lack of data showing an ergogenic effect, it is not clear what
the “proper” dosage should be. It also is not clear if there are sex
differences.
Contraindications
There is animal data that suggest potential adverse effects. For instance,
Australian tribulus has been shown to induce staggers (irreversible,
asymmetrical weakness of hindlimbs) and limb paresis in sheep; however,
there is no evidence this can occur in humans.
Precautions/Warnings
Clearly, more safety and efficacy data are needed to establish the
ergogenic (or ergolytic) effects of tribulus. There are no known harmful
interactions with other supplements or drugs.
Banned/Permitted
Neither the International Olympic Committee nor the U.S. Olympic Committee
currently includes tribulus on their lists of banned substances.
Legality
Tribulus is a legal substance.
References
- Antonio J. et al. The effects of
Tribulus terrestris on body composition and exercise performance in
resistance-trained males. Int. J. Sport Nutr. Exerc. Metab.10:208-215,
2000.
- Bourke, C.A. et al. Locomotor effects
in sheep of alkaloids identified in Australian tribulus terrestris.Aust.
Vet. J. 69:163-165, 1992.
- Dimitrov, M. et al. Use of tribestan
in rams with sexual disorders. Vet. Med. Nauki. 25:102-110, 1987.
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