Tribulus terrestris is mooted as a ‘super drug’ when it comes to improving sexual health in adult males as well as positively impacting testosterone levels.
But what scientific evidence is there to support these claims?
In this guide, we take a look at the facts when it comes to the efficacy of tribulus terrestris across a range of conditions for which it is reported to be effective.
Tribulus Terrestris: Can the hype be true?
The benefits of tribulus terrestris are claimed widely across the internet with most of the good news stories coming from manufacturers hoping to cash in on their products.
For every inconclusive case study there are at least a dozen reports as to why the findings should not be relied upon; for every supporting trial there’s a corresponding number of naysayers intent on denouncing the efficacy of this herb.
So what can you believe about the benefits of tribulus terrestris?
Does it actually work and, more importantly, does it work in humans?
Does Tribulus Terrestris Boost Testosterone?
Various studies have been undertaken on the effects of tribulus terrestris with respect to sexual hormones and blood androgens.
The majority of these have been performed using animals and largely concluded that the results were dose dependent.
In research carried out by Gauthaman et al., 2002 a dose of 5mg/kg was enough to prove an effective aphrodisiac in castrated rats.
When used in primates (rhesus monkeys and baboons), an intravenous dose of 7.5mg/kg of tribulus terrestris resulted in a significant rise in DHEAS, DHT and testosterone by 29%, 31% and 52% respectively (Gauthaman and Ganesan, 2008). Similar results were also seen in rabbits and castrated rats.
By contrast, a similar dosage administered orally showed no change in testosterone levels after 28 days in castrated rats.
Does It Work For Humans?
Relatively few studies have been undertaken in humans but those that have been carried out have produced inconclusive and, often, contradictory results.
These seem to vary depending upon who is sponsoring the research and what properties of tribulus terrestris are most desirable. The pharmaceutical market is predominantly looking to confirm the efficacy of one (or all) of the following claims:
- Increase muscle mass
- Improve strength and endurance
- Boost testosterone levels to improve mood, energy and libido
- To treat erectile dysfunction
In 2005, Neychev and Mitev concluded that neither a low or high dose of tribulus terrestris taken orally had any effects on LH or testosterone levels in healthy adult males. Their trial took place over 28 days and used two test measures of (10 mg/kg) and (20 mg/kg) plus a control group.
This research followed that of Van Eeenoo et al. (2000) in which test subjects were given a daily dose of 750mg/day of tribulus terrestris. The results from this test showed no change in urinary testosterone levels. Add to this those results obtained by Antonio et al., (2000) and Rogerson et al., (2007) and you could conclude that tribulus terrestris does not work in humans.
What Proof is there that Tribulus Terrestris…
In direct contrast to the studies above, clinical trials undertaken in 2009 and 2012 show proof that tribulus terrestris as a main component of dietary supplements actually does boost testosterone levels.
In the first trial, conducted by Milasius et al., (2009) conducted over 20 days showed a marked increase in blood testosterone as well as alactic and anaerobic muscular power in healthy young males.
A second test conducted in the same trials using older men who suffered from erectile dysfunction also proved the efficacy of tribulus terrestris over a 60 day period.
It should be noted that the tribulus terrestris extract was used in conjunction with N-acetylglucosamine, Alga Eckonia and D-glucosamine as part of a comprehensive supplement.
The results were therefore inconclusive as to whether tribulus terrestris alone improved both libido and testosterone levels or as part of a stacked cycle treatment.
…Improves Erectile Dysfunction?
A double blind study conducted in 2012 (Sellandi, Thakar & Baghel) over a period of 1-6 months across two groups of 18-29 and 30-44 year old men, concluded that 6g of tribulus terrestris was sufficient to produce a positive effect on erectile function as well as stamina.
Not only that but the trials reported a 16.3% increase in testosterone – however, this was not deemed of statistical significance.
Tribulus terrestris has been repeatedly shown in studies on both animals and humans to have an aphrodisiac effect, impacting libido positively.
In controlled tests on lab rats, tribulus terrestris was found to be as effective as Viagra.
In men with low sperm counts a 6g dose of tribulus terrestris was also found to improve sexual health by almost 50%.
In tests, tribulus terrestris has been shown to improve kidney function in diabetic rats, reduce aldose reductase and provide anti-diabetic properties.
In one test, a dose of 2g/kg tribulus terrestris was shown to be as effective as 10mg/kg glibenclamide in streptozotocin-induced diabetes to normalise AST, ALT and serum creatinine.
…Acts as a Diuretic?
Several cohort studies have been undertaken which support the evidence that tribulus terrestris works well as a diuretic.
Murthy, Dubey & Tripathi, (2000) gave a daily dose of 3g (fruit or water extract) to 75 patients suffering with hypertension and observed that daily urine output increased by 200ml.
…Decreases Blood Pressure?
There is some evidence in single double blind studies that tribulus terrestris has a positive effect on decreasing blood pressure in hypertensive individuals.
In the same trials performed by Murthy, Dubey & Tripathi, (2000), the same 75 individuals were noted to experience these benefits within just a week of treatment.
At present, there is insufficient evidence to determine whether these effects can be said to effective in normotensive individuals.
The same study above noted a small reduction in the cholesterol levels in some patients though again this was not considered of statistical significance.
Tribulus Terrestris is used in traditional therapies in Iran (and surrounding areas) as a means of pain relief.
Though there have not been very many trials to support this claim, one study conducted in mice did produce evidence to suggest that there is some basis.
An extract of tribulus terrestris was administered intravenously in doses of 50, 100, 200, 400 and 500 mg/kg and was found to be less effective than morphine but more effective than aspirin in reducing pain perception to heat and chemical pain tests.
No tests have been performed in humans as yet.
…As An Anti-Depressant?
Tests undertaken on stressed rats appears to show high benefits to tribulus terrestris as an anti-depressant.
At doses equivalent to a 2g dose on humans, tribulus terrestris exerted effects similar (but weaker) to diazepam and imipramine.
At these levels, both corticotropin and corticosterone (as well as adrenocorticotropic hormones) were reduced to normal levels and were as effective as a clinical dose of 1.8mg/kg of fluoxetine.
Does Tribulus Work?
So, is there any truth behind the claims that tribulus terrestris is an effective herbal supplement?
The fact is that more research is required in human subjects to determine the full extent of the efficacy of tribulus terrestris to boost testosterone levels but there is encouraging research to support the claims that this potent supplement offers a range of health benefits.
Certainly, the anecdotal evidence is strong which, in combination with clinical trials in animals, suggests that there is some basis to these claims.