T Nation



I've read through some of the posts on the above and appreciate the good advice. I feel that the above have made a difference for me as best I can tell but I have not taken TRIBEX or Alpha Male.

Here's my question though: which of the Trib/Eury products have documentable proof of raising T levels? I'd like to read the studies, look at the numbers and decide for myself which is the best product. Can someone point me to a link or two?


Also interested. I was looking for the main ingredient from RED KAT on Pubmed and couldn't find anything. Not doubting, I'm just curious.




I feel certain that Trib/Eury make a difference (at least for me) but what I wonder sometimes is if they really effect T that much. Maybe it's some other hormone/molecule - that's another reason I'd like to see some numbers.

And one reason I wonder is that I kind of doubt that GNC/Hi Health and other such places would keep anything on their shelves from a liability standpoint that had much of an impact on T.

Again, I do think they do something, but I just wonder if they really alter T-levels significantly...


Thanks, but I was looking for some primary sources.


My guess is you won't find any. Just a guess, but EVERY supplement company has been selling them hard for YEARS now, and I don't think I've EVER heard of any, in all their loud advertising and ballyhoo, mention any results from a double-blind study. But maybe I'm wrong.


Why don't you just have your T level tested prior to and after using these products for 4 to 6 weeks?

Research is all fine and dandy, but I'd rather see how a supplement works on myself. Besides, there have been plenty of supplements that were supported by research that flopped in the real world.


Good question and my primary reason would be money. $250 for two tests is a lot of cash for me right now. (I just got a house!) And, more importantly, I don't want to spend the money on a herb that has a low probability of helping me. If it doesn't work, that's over $300 down the toilet.

Plus, I have to ask, and I?m not being combative here, why the studies have not born out Trib as a T-booster? Correct me if I?m wrong, but Trib is a pretty old, well-established herb and I just can?t think of any reason that there wouldn?t be some decent studies showing increases in T-levels. Or, at worst, some studies showing positive increase in T-levels and some negative. But we don?t even have that situation from what I?m understanding.

In fact, let me ask the more obvious question: why not take a population of fifty year olds with depressed T-levels and give them Trib and post the results if Trib is a solid performer? This would be a huge boon to the herb and drastically increase sales. My only answer is the obvious.

But that said, I want you to know I think Trib increases libido and morning erections based on anecdotal experiences I have heard. But I have a lot of doubts that it does it via raised T-levels?


I seem to recall 2 or 3 research studies performed on TRIBEX that were reviewed on this site years ago.

I don't have any links, but you might try searching for TRIBEX research or something like that.


A few important points that I think people are missing.

  1. There is supportive evidence of these compounds being efficacious when it comes to increasing endogenous testosterone production. I'll past some references below.
  2. Medline or pubmed is not intended to be a source of "proof" nor is any database which has published studies (peer-reviewed or not). Proof as I've seen it used here does not exist, as it's implying that every last variable has been accounted for. Instead, these studies are there to allow others to view and interpret the data themselves, again, in support of or against a given hypothesis. Coming to a different conclusion from the authors is completely fine provided that there isn't an overwhelming body of evidence which would contradict your own conclusions.
  3. The second point is exemplified greatly in the following. In the particular study of a tribulus extract and the finding of no increase of testosterone levels, there are many areas to critique. First, you're talking about a crude plant extract. This has three main problems with it in this situation and in general.

  4. These extracts are "standardized" which simply means that the manufacturers providing the product give a loose promise that the plant contains no less than a particular percentage of the active constituent(s). As I've pointed out before in a previous article, when standardized green tea extracts were evaluated for catechin content, every last product failed to meet label claims, the best of which only had around 50% of the label claim. This is not really anyone's fault when you're relying on a standardized products, but it does easily create huge discrepancies when evaluating such products scientifically. This is one reason for isolating and purifying the compounds responsible for said benefits (more on that to follow below). It makes much more sense to use 750 mg of pure active constituents as opposed to 3,000 mg of a plant extract, "standardized" to contain 25% as this eliminates this concern.

  5. In the pharmaceutical industry and really just as a generally good idea, it's most always preferred to isolate the main active constituent(s) from a plant instead of having crude extracts. Two reasons for this include the idea that many times, a given plant may have other compounds which oppose the actions of the compounds thought to be responsible for the biological effects. The other is of course because many times, plants may also have other compounds which are toxic. There are certainly studies which one can locate which demonstrate a lack of efficacy from a given extract, yet the isolated compound worked, and there are also, again, studies where a given extract has demonstrated toxicity, while the isolated compound has not. Just to name a few, examples would be licorice root, commiphora mukul and cissus quadrangularis.

  6. Using extracts instead of isolated compounds limits the possibility of improving efficacy, namely in the way of improving pharmacokinetic aspects, specifically oral bioavailability. For example, I know that with the biologically active compounds in eurycoma, oral bioavailability is extremely low due to the high lipophilicity and consequent low absorption of the compounds, resulting in around 1% of a given dose actually reaching the bloodstream. This is why the nanodispersion delivery is used to address such an issue. Along these same lines, the active constituents in tribulus (protodioscin, methylprotodioscin and other similar analogs) also have a similar issue. In fact IV administration of protodioscin in primates was shown to increase LH and testosterone levels. This again goes back to addressing bioavailability issues which is what has been done with Alpha Male. The high sales and anecdotal evidence is hard for me to ignore with Alpha Male. This is what I do know. Alpha Male contains, if I remember correctly, close to 100% pure isolated compounds, thought to be responsible for biological activity. Whereas some companies have figured out how to do the same thing, they simply extract protodioscin, while ignoring its' analogs. They also ignore the issue of low absorption.

Last but not least, I was discussing this with a friend of mine not too long ago, and I don't think many understand the time, cost and effort involved in having a double-blind, placebo-controlled, randomized (with crossover) study performed in those who aren't in a diseased or abnormal state, only to have it published. Recruiting the subjects alone presents a problem. I see that most cynics want weight-trained males who have serious experience and so forth. Well, I think that most would find, when actually recruiting subjects in a given city or town, it's a bit hard to find, let's say 30 such guys who are willing to give up their current supplements, follow a specific weight training and diet routine, take time out of their day to stop at a lab for hours to have blood drawn, body composition assessed, record diet, obtain their pills, all under the premise that they "might" be taking the active compound for 12 weeks. In case they are lucky, they might receive a 25 or 50 dollar stipend.

In the particular case of Biotest, although I'm not the one who makes such decisions, I can see why it doesn't make much sense to invest a limited amount of research dollars in to a product which already has a large following and high sales when one can better invest money on future products.

Koumanov F, Bozadjieva E, Andreeva M, Platonva E, Ankov V. Clinical trial of Tribestan. Experimental Medicine 1982;2?4.

Gauthaman K, Ganesan AP, Prasad RN. ?Sexual effects of puncturevine (Tribulus terrestris) extract (protodioscin): an evaluation using a rat model.? J Altern Complement Med. 2003 Apr;9(2):257-65.

Gauthaman K, Adaikan PG, Prasad RN. ?Aphrodisiac properties of Tribulus Terrestris extract (Protodioscin) in normal and castrated rats.? Life Sci. 2002 Aug 9;71(12):1385-96.

Adaikan PG, Gauthaman K, Prasad RNV, Ng SC. Proerectile pharmacological effects of Tribulus terrestris extract on the rabbit corpus cavernosal smooth muscle in vitro. Annals Academy of Medicine, Singapore 2000;29(1):22?6.

Adaikan PG, Gauthaman K, Prasad RNV, Ng, SC. History of herbal medicines with an insight on the pharmacological properties of Tribulus terrestris. Ageing Male 2001;4:163?169.

Adimoelja A, Adaikan PG. Protodioscin from herbal plant Tribulus terrestris L. improves male sexual functions possibly via DHEA. International Journal of Impotence Research 1997;9(1):S64.

Tomova M, Gjulemetova R, Zarkova S, Peeva S, Pangarova T, Simova M. Steroidal saponins from Tribulus terrestris L. with a stimulating action on the sexual functions. International Conference of Chemistry and Biotechnology of Biologically Active Natural Products, Varna, Bulgaria, September 21?26, vol. 3. 1981. p. 298?302.

Gauthaman K, Adaikan PG, Prasad RNV, Goh VHH, Ng SC. Changes in hormonal parameters secondary to intravenous administration of Tribulus terrestris extract in primates. International Journal of Impotence Research 2000;12(Supplement 2):6 (Abstract).

T.K. Kwan, J.M. Saad , O. Farizaturradiah dan B.H. Koh. 1995. The Effect of Eurycoma longifolia on Rat and Human Testicular Steroidogenesis. Posiding Konvensyen Kebangsaan Tumbuhan Ubatan. FRIM. m/s 201-204.

Ali JM and Saad JM (1993); Biochemical effect of Eurycoma Longifolia Jack on the sexual behavior, fertility, sex hormone and glycolysis; Dissertation Paper for Bachelor of Science, Department of Biochemistry, University of Malaya.

Ang HH, Cheang HS. ?Effects of Eurycoma longifolia jack on laevator ani muscle in both uncastrated and testosterone-stimulated castrated intact male rats.? Arch Pharm Res. 2001 Oct;24(5):437-40.

Ang HH, Ikeda S, Gan EK. ?Evaluation of the potency activity of aphrodisiac in Eurycoma longifolia Jack.? Phytother Res. 2001 Aug;15(5):435-6.

Ang HH, Cheang HS, Yusof AP. ?Effects of Eurycoma longifolia Jack (Tongkat Ali) on the initiation of sexual performance of inexperienced castrated male rats.? Exp Anim. 2000 Jan;49(1):35-8.

Ang HH, Ngai TH, Tan TH. ?Effects of Eurycoma longifolia Jack on sexual qualities in middle aged male rats.? Phytomedicine. 2003;10(6-7):590-3.

Ang HH, Lee KL, Kiyoshi M. ?Eurycoma longifolia Jack enhances sexual motivation in middle-aged male mice.? J Basic Clin Physiol Pharmacol. 2003;14(3):301-8.

Ang HH, Sim MK. ?Eurycoma longifolia Jack enhances libido in sexually experienced male rats.? Exp Anim. 1997 Oct;46(4):287-90.

Ang HH, Ngai TH. ?Aphrodisiac evaluation in non-copulator male rats after chronic administration of Eurycoma longifolia Jack.? Fundam Clin Pharmacol. 2001 Aug;15(4):265-8.


Below is an abstract in support of tribulus from the same journal as that which found no significant increase in testosterone.

J Ethnopharmacol. 2005 Jan 4;96(1-2):127-32. Related Articles, Links

Effect of Tribulus terrestris on nicotinamide adenine dinucleotide phosphate-diaphorase activity and androgen receptors in rat brain.

Gauthaman K, Adaikan PG.

Department of Obstetrics and Gynaecology, National University Hospital, National University of Singapore, 5 Lower Kent Ridge Road, Singapore 119074, Singapore.

Tribulus terrestris L. (Zygophyllaceae) have been used as an aphrodisiac both in the Indian and Chinese traditional systems of medicine. Administration of Tribulus terrestris extract (TT) increased sexual behaviour and intracavernous pressure both in normal and castrated rats and these effects were probably due to the androgen increasing property of TT. The objective of the present study is to evaluate the effect of TT on nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d) activity and androgen receptor (AR) immunoreactivity in rat brain. Twenty-four adult male Sprague-Dawley rats were divided into two groups of twelve each. Group I was treated with distilled water and Group II was treated with TT at the dose of 5mg/kg body weight orally, once daily for 8 weeks. Following treatment transcardiac perfusion was done with Ringer lactate, 4% paraformaldehyde and 30% sucrose. The brain tissue was removed and sections of the paraventricular (PVN) area of hypothalamus were taken for NADPH-d and AR immunostaining. There was an increase in both NADPH-d (67%) and AR immunoreactivity (58%) in TT treated group and these results were statistically significant compared to the control. Chronic treatment of TT in rats increases the NADPH-d positive neurons and AR immunoreactivity in the PVN region. Androgens are known to increase both AR and NADPH-d positive neurons either directly or by its conversion to oestrogen. The mechanism for the observed increase in AR and NADPH-d positive neurons in the present study is probably due to the androgen increasing property of TT. The findings from the present study add further support to the aphrodisiac claims of TT.


Great questions. In respect to the published studies increasing sales. I used to think along the same exact lines prior to being given an eye opener to the supplement market. Biotest has had studies performed on supplements in the past (e.g., Methoxy-7, Myostat, etc.) each time with positive results. Well, the truth is that having these studies performed had absolutely no effect upon sales.

As for giving the product to older males and posting results, again, many will be quick to question what would happen in a different population, perhaps 18-35 year olds who have normal testosterone as I would suspect those are a greater percentage of the customers. Furthermore, one can question the validity entirely and rightly so, as it wouldn't be a randomized, double-blinded, placebo-controlled study.


I genuinely appreciate the list of articles and hope it wasn't too much trouble. One thing I noticed was that the majority of them deal with libido and sexual function (in animals). Now that's interesting to me, because from what I have heard anecdotally, that is the strongest value in Trib.

Q for you: in general do endocrine-related studies on animals apply well to humans?


Well, I can accept what you're saying to a certain extent, but I still find it odd. Look at Saw Palmetto, St. John's Wort, etc.: these herbs have been studied ad nauseum by the clinical community. I just don't understand why Trib would receive a much more "hands off" treatment?


Absolutely. The reason for the consistent use of animal models within the literature is because they have been shown to be effective models in the past. The use of dogs in the pioneering work on diabetes is an excellent example.

However, as a note of caution, animal models work best for qualitative and not so much for quantitative purposes.


Really the only time you see a great deal of funding for studies are when you're talking about herbs or plants that a great deal of people in the population are going to use. St. John's wort being touted as an antidepressant and Saw Palmetto being touted for prostate health are both hitting huge areas of concern amongst the general population. Ginkgo biloba is another example as compounds being used to improve cognitive function are something the general population has an interest in.

The general population, however, is not concerned with having higher testosterone levels, as shocking as that may be to some of us.

Again though, this isn't to say there isn't any data on the plant, just not nearly as much.


Thanks Mr. Wilson for posting the studies and brining up some excellent points.

I'm always skeptical of published studies now that I know how they work, but I wanted something tangable to shove in someone else's face to convince them (even though they technically shouldn't be just because of a study). Sort of an ends justifies the means sort of thing.


Cy you rock, thanks for the replies...
I didnt take much into stock about the trib studies, there are just soooo many variables. I know from my experiences dealing with growing plants(use your imagination, LOL) that there are so many variables that come into play that can affect potency of a particular plant.

Something as simple as the region/climate/area it was grown, can affect a herbs potency BIGTIME. the way a plant is grown and extracted and taken care of has a dramatic effect. And thats not even getting into the issue of Nano-Dispersion/oral bioavailablity, which is another whole ballgame.


Can?t argue with you there. It?s a relatively small subset of the population that cares anything about fitness and health. It?s an even smaller subset that want to go even more granular and worry about the level of a specific hormone.

Btw, I read somewhere that T is used to build serotonin. Any truth to that? If so, it explains why sex and T are so integral to our nature especially as guys?



Great thread.. I just thought everyone should read this again..