Scientific Analysis of Over-the-Counter Testosterone Boosters
by Jay McCombs
Introduction
Question One: What do you get when you mix 19 molecules of carbon, 28 molecules of hydrogen, and 2 molecules of oxygen? It could be a lot of things, but maybe (if you are lucky) it could order into 17beta-Hydroxyandrost-4-en-3-one. Sound familiar? That's right, it's your friend and mine testosterone.
Question Two: How can you increase your body's natural production of testosterone? That's a tougher one. Pro-hormones are no longer easily obtained legally and personal stashes will soon dwindle, making this question even timelier.
In the next few pages I will review the scientific literature through exhaustive searches of Medline, CINAHL, EBM, and SPORTDiscus with regard to some of the most popular Over-the-Counter testosterone boosters currently on the market. I will examine the possible mechanism of action for each and assess whether any of these alleged testosterone boosters have a positive effect on testosterone production, exercise performance, or both.
Tribulus Terrestris
The first on the list is of course Tribulus Terrestris, specifically the steroidal saponin protodioscin. Tribulus has long been used in various cultures as an aphrodisiac and treatment for sexual dysfunction. The theory then follows that this increase in libido is probably due to increased levels of androgens, which would also mean that Tribulus generates some type of ergogenic effect. So what does the research say?
First lets look at several studies conducted on animals that examined the aphrodisiac properties of Tribulus. The first study investigated the response of corpus cavernosal tissue isolated from rabbits that were fed Tribulus for eight weeks [1]. After harvesting, tissues were then exposed to protodiscin, contractile agents, and relaxant agents. Tissue strips from treated rabbits showed an increased rate of relaxation when administered various relaxing agents after said tissue was constricted with norepinephrine. This indicated that Tribulus seemed to have some effect on the rabbits’ ability to get erections; however, no specific mechanism could be pinpointed.
Follow up research ensued. The next two studies, conducted on castrated rats, examined variables that essentially investigated how sexually aroused the rats were [2, 3]. The researchers found that Tribulus supplementation definitely appeared to increase the rats libido. Again however, an exact mechanism could not be found.
The latest study by the same researchers tried to determine the mechanism of action by which the mice and rats each appeared to experience heightened arousal levels [4]. Once again, rats were fed Tribulus for 8 weeks. Immunoreactivity studies were performed on the androgen receptor (AR), while Nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d) levels were taken from the rat paraventricular nucleus in order to determine activity.
The researchers found activity at both receptors increased over control; however, this muddied the waters a bit. NADPH-d neurons are the same that contain NOS. Previous research indicated these neurons were inhibited by increased androgen activity. The researchers attributed this to effects mediated through the conversion of androgens to estrogen, which would then increase the number of NADPH-d neurons. The end result was the same: Tribulus undoubtedly heightened arousal, but whether this was a result of increased androgen levels was unclear.
So, rats having sex is fun to watch, but we want to get buff, right? Well, lets talk about primates. Primates given Tribulus intravenously showed a transient (read, 30 minutes) increase in testosterone and DHT and a longer increase in DHEAS (an increase of about 25-50% for about 120 minutes), which might be helpful with DHEA mediated effects on sexual function if your testosterone was low [5]. Otherwise, this effect probably would not be noticeable.
In my opinion, the nail in Tribs coffin comes from the following two studies. The first study examined body weight, body composition, maximal strength, dietary intake, and mood states of subjects before and after 8 weeks of taking either a Tribulus extract or a placebo [6]. No significant change was found in any of these parameters after supplementation with Tribulus when compared with the placebo group.
The next study evaluated claims that LH and subsequently testosterone levels were increased above normal after ingesting Tribulus extracts [7]. Baseline levels of testosterone and its metabolites in urine and serum were established for all subjects. Participants were then fed a heaping gram of Tribulus daily for 4 weeks. Testosterone levels were checked routinely, and researchers found no significant increase in hormone levels beyond normal day to day variations. This research is the most significant and relevant to our discussion here today. It was conducted on humans and looked for the two variables we are most concerned with: increasing testosterone and, in turn, increasing exercise performance—and in both of these studies Tribulus failed to do either.
I just briefly want to discuss the Sopharma research. This research was not included in this review for several reasons. It has not been published in a reputable English language journal and subsequently peer reviewed; and, subsequent research has been unable to elicit the same results when conducted in a similar manner [7].
In my opinion Tribulus is not useful for increasing androgen levels in healthy males or improving exercise performance. There may be some effect on individuals with androgen deficiencies where Tribulus acts as a precursor to deficient DHEA, but at this time the only conclusion that can be definitively drawn about Tribulus is that it seems to be quite effective at making castrated rats horny [8].
Also Iv'e already posted this in a complete analysis of Over the Counter Testosterone boosters. Becuase these questions get asked so many times. Please use the seacrh function I don't hagve the time to re post over and over again. |