Does Tribulus Terrestris Work?

Bodybuilders and other athletes working hard to increase their muscle mass and strength are constantly on the lookout for better supplements to help them accomplish that. These athletes pay close attention to any product that claims to increase strength. For many a year, they’ve turned to anabolic agents such as synthetic testosterone. Nowadays, with “better” education and a marketplace full of products, more and more athletes are trying out natural herbal and other preparations. Many have become aware that natural supplements simply work more elegantly and holistically with the body’s own natural metabolic and endocrine systems, which tends to yield better longer-lasting results.


Tribulus Travels

Currently, one of the most widely-used natural products is Tribulus terrestris. T. terrestris, or tribulus for short, is a thorny plant that grows in mats close to the ground and bears fruit with sharp spines. Tribulus has been used medicinally for thousands of years, notably in China and India. In the 1970s, the Bulgarian company Sopharma began marketing a tribulus product named Tribestan® for strength improvement. Because of its claimed beneficial effects on testosterone and thus on strength and size, tribulus is now found in dozens of products from companies like Now, Infinite Labs, MHP, Nutrex, and others.


But Does It Work?

But does Tribulus terrestris work? True, it is heavily marketed and bought in large volume. Since products containing tribulus usually claim to be “testosterone boosters”, they will be eagerly bought and consumed. The important point for the hard-working athletes who try these products, though, is whether the products actually provide the claimed and hoped-for effect. The mechanism by which tribulus is supposed to raise testosterone is by encouraging the secretion of luteinizing hormones, which leads to increased testosterone, sperm production, and libido. Medical use and research in parts of Europe has indicated that in certain young patients with undeveloped gonads, or hypogonadism, tribulus use leads to increased pubic hair growth. This suggests that testosterone is higher in those patients, which in turn usually leads consumers to believe that they will get steroid-like effects from products containing tribulus.


Back To The Beginning

The story of tribulus begins with its age-old use as a medicinal herb in Chinese traditional medicine and Indian Ayurvedic medicine. In China, it was thought to be effective for skin and eye irritation, weak milk production, and disorders of the urinary and reproductive tracts. In India it was known as an aphrodisiac. In Eastern Europe decades ago, it started (or continued) being used as a libido tonic which enhanced sexual activity by means of longer and stronger erections. In addition, it stimulated production of more and more active and viable sperm. Outside of eastern Europe, there has hardly been any research on tribulus at all. Most of the research even in eastern Europe has been sponsored by Sopharma, the Bulgarian company that first marketed Tribestan®. Despite thousands of years of use, little scientific knowledge about tribulus has accumulated until recently. That first eastern European use of tribulus as a “tonic” to treat sexual dysfunction was only the beginning. Once its interesting effects were noticed and talked about, it was only a short time before it was applied to raise testosterone levels and hopefully stimulate muscle weight gain. Without scientific understanding, however, administering a substance to patients that meddles with their hormones is hit-or-miss at best and more likely foolhardy. What do scientists have to say about tribulus?


Better Living Through Chemistry

The data on tribulus at this point is still inconclusive. Some of the reported results suggest that it may be effective and mostly clear of detrimental side effects. In particular the eastern European research reports indicate that it increases circulating serum testosterone, with side effects of greater mental acuity and alertness, which would be expected if testosterone were elevated. However, there is little information about optimal dosing or conditions for the best responses. Tribulus left its first modern footprints in the scientific literature in 1978, when a patent and licenses were granted in Bulgaria for “An agent for stimulation of sexual function”. In 1980 – 1982, a number of research papers studying a substance called Tribestan® were published , mostly as “Scientific-Technical Reports” and a smaller number in scientific journals. One of those studies on which the reputation of Tribestan®, the first tribulus supplement, were based, is this one (not a Scientific-Technical Report, but Sopharma Company documentation): Milanov, S., E. Maleeva, M. Tashkov. Tribestan effect on the concentration of some hormones in the serum of healthy subjects (Company documentation)(1981). The gist of this study was that healthy men were given 750 mg of Tribestan® per day for five days, and experienced a 72% increase in luteinizing hormones and a 40% increase in testosterone, while estradiol also increased 81%. According to the study, testosterone did increase, but according to existing knowledge of hormones, whenever you raise testosterone levels, aromatization also increases, making estrogen levels go up, too. Furthermore, the significance of these increases should be understood correctly. The normal male testosterone range is around 300 – 1000 ng/dL, and the study listed the subjects’ starting levels as 600 ng/dL and the ending levels as around 850 ng/dL. This is easily still a normal reading. So testosterone did not increase very much. But what did increase very much was the estradiol levels. The normal male range for estradiol is 20 – 80 pg/ml, and the study increase was from 76 pg/ml to 137.5 pg/ml, far out of the normal range. Other studies showed that for men with serum testosterone below the normal range, treatment raised their readings to within normal levels, but in men with normal starting levels, treatment had no significant impact on their testosterone levels.


The Plot Thickens

Much more recently, further studies have been conducted in Australia and the US. Some of these studies are shown below.

Effects of anabolic precursors on serum testosterone concentrations and adaptations to resistance training in young men Brown GA, Vukovich MD, Reifenrath TA, Uhl NL, Parsons KA, Sharp RL, King DS, Int J Sport Nutr Exerc Metab 2000 Sep;10(3):340-59

In this study the subjects carried out 3 days of resistance training every week for 8 weeks. Most days during the study, the experimental group subjects took a supplement containing daily doses of 625 mg of Chrysin, 750 mg of Tribulus terrestris, 300 mg of androstenedione, 150 mg of DHEA, 300 mg of Indole-3-carbinol, and 540 mg of Saw palmetto. The conclusion stated: “These data provide evidence that the addition of these herbal extracts to androstenedione does not result in increased serum testosterone concentrations, reduce the estrogenic effect of androstenedione, and does not augment the adaptations to resistance training.” The short version: did not raise serum testosterone.

The effects of Tribulus terrestris on body composition and exercise performance in resistance-trained males Antonio J, Uelmen J, Rodriguez R, Earnest C Int J Sport Nutr Exerc Metab 2000 Jun;10(2):208-15

Here, the subjects were given tribulus in the amount of 3.21 mg/kg body weight each day. In the end, two statements stand out: “There were no changes in body weight, percentage fat, total body water, dietary intake, or mood states in either group” and “Supplementation with tribulus does not enhance body composition or exercise performance in resistance-trained males.” Short version: no effect on body composition or muscular strength.

The aphrodisiac herb Tribulus terrestris does not influence the androgen production in young men Neychev VK, Mitev VI J Ethnopharmacol 2005 Oct 3;101(1-3):319-23.

In this study, 21 healthy young men aged 20-36 years old took either 20 or 10 mg/kg body weight per day of Tribulus terrestris extract. Testosterone, as well as androstenedione and luteinizing serum hormone levels were tracked. The result was that “the findings in the current study anticipate that Tribulus terrestris steroid saponins possess neither direct nor indirect androgen-increasing properties.” Short version: did not increase androgen.

The effect of five weeks of Tribulus terrestris supplementation on muscle strength and body composition during preseason training in elite rugby league players Rogerson S, Riches CJ, Jennings C, Weatherby RP, Meir RA, Marshall-Gradisnik SM J Strength Cond Res. 2007 May;21(2):348-53.

The experimenters noted that products tended to promote the idea that tribulus would lead to big increases in strength and in 5-28 days on muscle mass, strength, and other measures during 5 weeks of preseason training. They tracked muscular strength, body composition, and other levels. In the end they stated, “It was concluded that T. terrestris did not produce the large gains in strength or lean muscle mass that many manufacturers claim can be experienced within 5-28 days.” Short version: no gains in strength or muscle mass claimed by manufacturers even in 5 weeks, not to mention 5-28 days. Several astute observers have noted, that if a man is over 25 and thus has falling testosterone, then tribulus may help with his sexual performance via temporarily increased testosterone, but that for athletes who desire size and strength gains, tribulus is useless.


From The Trenches

The best recommendations from the athletes themselves seem to be for those in training to eat healthy, natural food. That will make all kinds of things work better, including raising testosterone levels naturally. Natural supplements like creatine, glutamine, whey, and others are also worthwhile. Many if not most athletes these days have serious doubts about the evidence that is touted as being in favor of positive strength gain effects of tribulus. Most studies fail to replicate the luteinizing hormone data. There is no reliable evidence of any improvements actually occurring. There are only subjective anecdotes about libido changes coupled with marketing claims aimed at selling more products to eager weight lifters. There is widespread though not universal agreement that there is no noticeable effect of even the original Bulgarian tribulus, except for the possibility that it increases libido.


What Does It All Mean?

After all this information, what conclusion can we come up with? Does Tribulus terrestris work? There appears to be some scientific literature about tribulus in languages other than English – including at least Russian and Bulgarian, but probably also Chinese, and others as well. The independent English language studies that we can definitely believe indicate that tribulus is NOT useful for strength and mass gain. However, it is possible that there are as yet unknown factors which the Bulgarian studies may have taken into account. At present, though, all we can do is to believe the best information we have available, from the independent English-language studies. Tribulus does appear to help with sexual matters. It may possibly help with some of the ailments traditionally treated with it in India and China. One thing that Tribulus terrestris does not seem to be effective for is gaining muscle strength or mass. The independent studies are few, but they are what we have to go on right now. The future will tell if some new combination or protocol will show more significant results than anything has done so far. One problem with a lot of studies is that they try to take elements out of their context, losing synergistic effects, in which the whole would have been greater than the sum of the parts. Then of course it will lose effectiveness. Until more studies are performed, it’s up to anecdotal evidence or just trying it to determine its true effectiveness. The bottom line here is to be weary of all those supplement ads you read…go to the research! And beyond that, always remember the true medical principle of you being the n value of a study and as a patient n is always 1 or you’re a chop-shop physician.