Tribulus Terrestris

I don't know where you got this information from, but it is full of hype.

Tribulus terrestris is a prostrate, matforming plant. Although it has been used by the Chinese for thousands of years, little was scientifically known about it until recently. Tribulus is said to increase testosterone levels by as much as 30%, especially when taken in conjunction with sopharma. The primary mechanism of action to explain this phenomenon is that tribulus stimulates the secretion of lutenizing hormone (LH) from the anterior pituitary gland. This in turn stimulates testosterone production, as well as growth hormone and estradiol. Therefore, tribulus can easily stimulate gynecomastia (gyno) and insulin resistance.

Tribulus was shown to raise testosterone in men and estradiol in women with a slight increase in testosterone in women as well.  Testosterone is an antagonist to estradiol, which means it can prevent gynecomastia.  In order to cause gynecomastia in men there would have to be an abnormally high level of aromatase, which converts the testosterone in to estrogen.

As far as insulin resistance this is also misleading.  Again testosterone and estrogen have different effects.  Testosterone increases muscle production and decreases body fat, which in turn DECREASES insulin resistance.  Estrogen can increase body fat and increase insulin resistance.

This is very negative for bodybuilders. In women, tribulus stimulates follicle-stimulating hormone (FSH) and estradiol, but not testosterone.

Actually it does increase testosterone in women, just to a much lesser extent than in men.

750-1200 mg/day dosages are not uncommon and is usually stacked with 100 mg/day of DHEA (discussed later)

DHEA should not be played with.

and 100 mg/day of androstenedione.

Same as above.  It should not be played with.

Although the rise in testosterone levels may sound attractive to many athletes, the side effects are much more dire than gynecomastia and insulin resistance. Tribulus Terrestris has been shown to dilate the coronary arteries (Wang, 1990)

LOL!!!!  Duh!!!!  Sterols relax blood vessels increasing blood flow including to the heart.  Improving blood flow to the heart is not a bad thing.  DECREASING blood flow to the heart is a bad thing, especially for athletes.  in fact, here is the study abstract:

http://www.ncbi.nlm.nih.gov/pubmed?term=406%20cases%20of%20angina%20pectoris%...

"Zhong Xi Yi Jie He Za Zhi. 1990 Feb;10(2):85-7, 68.

[406 cases of angina pectoris in coronary heart disease treated with saponin of Tribulus terrestris].

and has a diuretic effect (Arcasoy, 1998).

As do many other things including purified waters.  So what?  Not all diuretics are dangerous.  Watermelons are diuretic, should they be avoided?  How about bananas?  Parsley? Kiwis? Papaya?............

In both cases, this can put the athlete in a dangerous state.

Again, a lot of hype!!!

Bourke (1995) found that severe nervous and muscular locomotor disorders are directly associated with tribulus terrestris ingestion.

Pretty vague statement and again very misleading.  If you look up this actual study ("Locomotor effects in sheep of alkaloids identified in Australian Tribulus terrestris") you will find that first of all the claim is based on sheep studies, which does not correlate to humans.  Secondly the sheep were overdosed with synthetic alkaloids, harmane and norharmane, found in tribulus, not tribulus itself. The sheep were given the equivalent of 1.2kg of raw herb for every kg of body weight!!!  Based on that kind of reasoning we can conclude that all pharmaceutical drugs have a 100% mortality rate.  This is a great example of why we should actually look at studies being cited instead of relying on misleading opinion sites that fail to present their actual references for fear that someone will actually read the studies and see how they are trying to mislead people.

The production of bile stones is also greatly enhanced (Miles, 1994)

Again sheep studies:

http://www.ncbi.nlm.nih.gov/pubmed/7501366

http://www.ncbi.nlm.nih.gov/pubmed/7596574

due to hyperplasia of the bile ducts and diffuse swelling of hepatocytes (Tapia, 1994).

Yet another sheep study reporting the effects of sheep grazing on tribulus:

http://www.ncbi.nlm.nih.gov/pubmed/7975136

This also brings up another point.  The sheep are grazing on the whole plant.  But tribulus terrestris, also known as puncture vine or goat's head here locally,  uses the seed component in alternative medicine.  Different parts of a plant can have different properties.  Are tomato fruits deadly just because the leaves contain deadly solanine?

Gauthaman et al. (2005) suggests that tribulus stimulates androgen production,

Yes, that is what testosterone is.

an effect similar to that of prohormones and prosteroids. For more on prohormones, read The Truth About Prohormones. As noted above, tribulus increases the risk of developing gynecomastia.

And again very misleading as already addressed.

Jameel et al. (2004) confirms this by stating that the increased incidence of gynecomastia in young male athletes is a direct result of the increased use of steroids and tribulus terrestris.

Again, true gynecomastia is a result of elevated estrogen, not testosterone.  And in order to increase estrogen from testosterone the person would have to have abnormally high levels of aromatase in the first place.  Also note in the abstract that he was taking an herbal supplement containing tribulus:

http://www.ncbi.nlm.nih.gov/pubmed/15454201

Problem is that it does not say what else was in the tablet, nor any other factors such as his diet, was he really male, etc.  A person can have a male body and female chromosomes, or even ovaries within the body.  So the abstract left out a lot of important information and the author ran with it anyway since the goal was clearly to bash tribulus.

Other evidence suggests that the heavy diuretic effect of tribulus can cause kidney damage.

Again not true.  It is not even that strong of a diuretic to begin with.

Tribulus also contains a compound called saponin, which is a class of glucosides.

Saponins are not an individual compound, they are a group of compounds with various beneficial effects to the body depending on what they are bound with.  For example, steroidal saponins can not only reduce inflammation, but they also lower blood pressure.

Saponin derived from tribulus has been shown by Li et al. (2002) to elicit a hypoglycemic effect.

A mouse study, again not applicable to humans:

http://www.ncbi.nlm.nih.gov/pubmed?term=Li%202002%20tribulus

Serum glucose is significantly lowered with tribulus supplementation, which has negative effects on insulin sensitivity and central nervous system function (the CNS runs solely on blood glucose).

Again this is based on a mouse study.  But even at that the reduction was lower in healthy mice and higher in diabetic mice.  The saponins also lowered cholesterol and triglycerides, which is important especially for diabetics.  And the saponin increased SOD activity, which leads to reduced inflammation and increased immunity.  Again, especially important to diabetics.  So the author, who clearly does not understand medicine, took the abstract totally out of context to do a hatchet job on tribulus.

A result of prolonged tribulus supplementation may be diabetes.

ROTFLMAO!!!!!  How did he come up with that claim?!!!  Not one study he has presented even hints to that claim.

Further investigations by the same researchers found that tribulus lowers plasma HDL (“good” cholesterol)

Steroidal saponins are well known for lowering "dangerous" LDL cholesterol, not healthy HDL cholesterol.  No wonder he did not provide a reference to this claim.  Saponins are not even absorbed to lower cholesterol in the blood.  The way they work is that they bind to bile cholesterol when the bile enters the intestines forming an insoluble complex that is excreted instead of being reabsorbed as normal.  Steroidal saponins will also bind to dietary cholesterol

As a side note, steroidal saponins are also well known for destroying cancer cells and many pathogens by binding to and ripping out cholesterol from their membranes.  This is why jiaogulan (Gynostemma), which is the highest herbal source of sterols I have seen has a long history for the treatment of cancer.  It is the sterols bound to some saponins that bind and lower cholesterol.

levels and severely restricts gluconeogenesis activity in the liver.

This is believed to be how tribulus lowers glucose.  But according to the study the author presented the effect was not that strong since the drop was only really significant in diabetic mice, but not healthy mice.

Antonio et al. (2000) assessed the effect of tribulus supplementation (in high doses) on trained male athletes. Over the course of the investigation, there were no changes in body weight, percentage fat, total body water, dietary intake, or mood states in either group. Slight increases in muscle strength were found in the tribulus group compared to the placebo, but the results were not significant. Antonio and his associates concluded: “Supplementation with tribulus does not enhance body composition or exercise performance in resistance-trained males.”

LOL!!!  In "high doses"?  Again here is the study the author was referring to:

http://www.ncbi.nlm.nih.gov/pubmed?term=Antonio%202000%20tribulus

Note the participants were only given 3.21mg per kg of weight.  So a person that weighs 180 pounds (roughly 82kg would have only received around 263mg of tribulus daily.  Being that one capsule averages 500mg this means that this person would get less than a half a capsule daily of the herb when to see any results they would need at least 3 capsules 3 times daily!  So the participants were not give anywhere near high doses, they were given extremely low, ineffective doses.   

Based on the available evidence, tribulus terrestris is an extremely dangerous supplement and cannot be used in a safe manner. Its supplementation should be avoided by all athletes at all times.

Based on the evidence the author had no idea whatsoever what he was talking about and needs to learn how to do real research as well as how the body works.