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. This is very negative for bodybuilders.
In women, tribulus stimulates follicle-stimulating hormone (FSH) and estradiol, but not testosterone. 750-1200 mg/day dosages are not uncommon and is usually stacked with 100 mg/day of DHEA (discussed later) and 100 mg/day of androstenedione. 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) and has a diuretic effect (Arcasoy, 1998). In both cases, this can put the athlete in a dangerous state. Bourke (1995) found that severe nervous and muscular locomotor disorders are directly associated with tribulus terrestris ingestion. The production of bile stones is also greatly enhanced (Miles, 1994) due to hyperplasia of the bile ducts and diffuse swelling of hepatocytes (Tapia, 1994).
Gauthaman et al. (2005) suggests that tribulus stimulates androgen production, 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. 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. Other evidence suggests that the heavy diuretic effect of tribulus can cause kidney damage.
Tribulus also contains a compound called saponin, which is a class of glucosides. Saponin derived from tribulus has been shown by Li et al. (2002) to elicit a hypoglycemic effect. 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).
A result of prolonged tribulus supplementation may be diabetes. Further investigations by the same researchers found that tribulus lowers plasma HDL (?good? cholesterol) levels and severely restricts gluconeogenesis activity in the liver. 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.?
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."