I posted this already in the "general" section, sorry. I figure it would do better in the science area.
The following is from howstuffworks.com and wikipedia. Ive been taking this stuff for about a month now, and I'm really not sure if it does what it claims.
"The athletic world touts tribulus terrestris as a natural alternative to artificial steroids. Some people believe using tribulus terrestris can affect the body's muscle composition and improve a person's success with bodybuilding. Tribulus terrestris may contribute to an athlete's improved performance and add to an athlete's muscle mass [source: Monson and Schoenstadt]."
"There are several claims circulating that say tribulus terrestris is both safe and effective in helping athletes build their muscles, and that it avoids all the negative side effects of using steroids. The theory is that there are three chemicals found within the plant that might help foster the growth of muscles and activate the production of testosterone. Those three phytochemicals, meaning chemicals found within a plant, are dioscin, protodioscin and diosgenin [source: Chinese Herbs]."
"It is important to remember that the scientific and medical communities have not yet verified any of the claims made about tribulus terrestris. All of the claims you hear about tribulus terrestris heightening the ability of cells and tissues to absorb the most protein and energy from food are generally speculations based on sparse studies [source: Chinese Herbs]."
Now I've seen some articles on BB.com state that this product is effective in increasing testosterone, but a number of places insist its just speculation and that there are no consistent studies that can prove these facts.
"Animal studies in rats, rabbits and primates have demonstrated that administration of Tribulus terrestris extract can produce statistically significant increases in levels of testosterone, dihydrotestosterone and dehydroepiandrosterone, and produces effects suggestive of aphrodisiac activity. On the other hand, one recent study found that T. terrestris caused no increase in testosterone or LH in young men, and another found that a commercial supplement containing androstenedione and herbal extracts, including T. terrestris, was no more effective at raising testosterone levels than androstenedione alone."