Tribulus (or, as its sometimes called – Puncture Vine, Devil’s Weed or Tribulus terrestris) has been marketed for ages as a natural testosterone / libido booster. A flowering plant, tribulus contains some very interesting steroid like substances called saponins, one of which is called protodioscin.
Protodioscin is a chemical “cousin” of DHEA, a steroid hormone produced by the adrenal glands, and incidentally, the only “hormone” not effected by the U.S. prohormone ban of 2005.
Although some supplement retailers are still selling DHEA-based supplements and trumpeting its anabolic characteristics, it is a long established fact that DHEA…
“… does not effectively increase serum testosterone levels and fails to produce any significant changes in lean body mass, muscle strength, or performance improvement compared with placebo” (Pediatr Clin North Am. 2007 Aug;54(4):787-96).
How does tribulus “work”?
Well, if you believe the retailers, it works by stimulating the production of luteinizing hormone in the pituitary gland, thus encouraging the body to crank up its own testosterone producing process.
Of course, advertising and peer-reviewed data are two completely different things.
I remember when I was first introduced to tribulus back in the early 90’s. It was a pretty hyped product at the time — especially the Tribestan brand of tribulus, which had a series of pretty impressive clinical studies backing up its claims.
And of course, there were the stories of the Bulgarian weight lifters who were apparently trouncing their competition, all thanks to tribulus and of course, Tribestan.
Is tribulus really all that effective at boosting test levels? What do the most recent scientific studies say about this?
Despite the “glowing” Bulgarian studies, I was unable to find any positive evidence in published Western journals. That’s not surprising really, since old “Eastern Bloc” data is notoriously unreliable.
The data I did find was much less promising, and a bit troubling, to say the least.
For instance, this study (Int J Sport Nutr Exerc Metab. 2000 Jun;10(2):208-15) concluded…
“Supplementation with tribulus does not enhance body composition or exercise performance in resistance-trained males.”
And this study (J Ethnopharmacol. 2005 Oct 3;101(1-3):319-23) concluded…
“The findings in the current study anticipate that Tribulus terrestris steroid saponins possess neither direct nor indirect androgen-increasing properties.”
In other words, tribulus supplementation does not affect testosterone levels.
The most recent study I found (J Strength Cond Res. 2007 May;21(2):348-53) was conducted on Australian rugby players… none of whom received any perceptible benefit from tribulus supplementation.
Of course, you won’t find these most recent studies referenced in the sales material of the current test boosting supplements – you know the ones, talking about the “controversy” surrounding these new steroid alternatives and what not.
So why does it continue to be such a popular supplement?
A Strong Placebo Effect?
Why then, despite the complete lack of clinical evidence validating increased androgen production, do many tribulus users appear to be happy with the product?
I know plenty of guys who use the stuff religiously, many of whom claim to feel better—even stronger, when supplementing with tribulus.
Well, there’s no discounting the placebo effect. Sometimes, the mere suggestion that you’re taking something powerful and effective is enough to elicit a response.
I have a hunch though, that tribulus’ real benefit is in boosting the libido and acting as an aphrodisiac, and it is this “benefit” that tribulus users enjoy so much.
One friend tells an absolutely hilarious story about how he unwittingly took his first dose of tribulus just prior to a Mexican vacation with his girlfriend and her parents.
He spent the entire flight sitting petrified beside her father, with his lunch tray flattened over his lap to conceal his “condition.”
Such… uh… conditions—however “beneficial” they may be—aren’t necessarily evidence of increased androgen production (and the western evidence certainly does not support that argument), but could be a result of any number of different mechanisms (witness how a drug like Viagra works, for example).
And, while there’s no real human clinical data validating the plant’s libido-boosting characteristics, there are a couple of animal-based studies that validate its effects in this regard (see Life Sci. 2002 Aug 9;71(12):1385-96, J Altern Complement Med. 2003 Apr;9(2):257-65).
Although there is some contradictory evidence for the testosterone-boosting effects of tribulus, all the most recent published western data suggests tribulus is a dud for androgen production.
However, that doesn’t mean tribulus supplementation offers no benefit at all.
It’s value may lie in its ability to boost the libido / increase erections, and for that reason alone it may be worth experimenting with.
Don’t spend a ton of money on a specialty product though. Plain tribulus is cheap enough — you can buy 100 capsules for under $14 at BodyBuilding.com.
For such a small investment, it’s probably worth trying… especially if you have “troubles” in the libido and / or erection department. Just don’t expect to build massive muscles on the stuff… that just isn’t going to happen!