In several studies, Tribulus has demonstrated aphrodisiac properties that were originally thought to be the result of increased testosterone. This is mainly due to Tribulus being shown to increase levels of testosterone in certain animal studies. A 2005 study, published in the “Journal of Ethnopharamcology” found that 200mg daily (60% saponin content) had no effect on testosterone in healthy men. These results were replicated in a 2007 study in which 450mg of Tribulus extract daily failed to influence testosterone levels in male athletes. Even a 2012 study, this time testing the effects of 6g of Tribulus extract on infertile men, found a less than significant trend towards increased testosterone. Ultimately, the popularity of Tribulus as a testosterone booster seems unwarranted given than it has unreliably increased testosterone in rodents and has never been shown to significantly increase testosterone in humans, healthy or not. Tribulus may increase libido and sexual well-being, creating the illusion of increased testosterone, but the science is very clear: Tribulus does not increase testosterone in healthy humans.
Eurycoma Longifolia, also known as Tongkat Ali has been shown, in various studies, to increase testosterone in male rats, but there are currently not many human studies. A 2010 study published in the Asian Journal of Andrology found that supplementation with 200mg of an extract of Eurycoma Longifolia significantly improved various indications of male fertility (in humans), though the mechanism of action was unknown. Until just recently though, no study had been done with humans to test the effects this extract has specifically on testosterone. Rat studies would have been all we had to go on, and as we have mentioned in countless analyses, just because it works in rats doesn’t mean it works in humans. However, a 2012 study published in “Andrologia: Volume 44” (the same researchers from the above mentioned human study) found that men suffering from hypogonadism (diminishing functionality of the gonads) who were treated with a 200 mg daily dose of Eurycoma longifolia extract reached normal testosterone levels after a 30 day period. To be fair, at the start of the study about 35% of the men were showing normal testosterone levels, and at the end about 90% showed normal levels. Still, 35% to 90% is clearly statistically significant. That being said, there is just one more thing to take into account: the subjects in the study had abnormally low testosterone and were able to return to normal after supplementation. The present study does not show that males with normal testosterone can achieve abnormally high levels of testosterone via supplementation with Eurycoma longifolia. While a further study will be needed to confirm this effect, the facts certainly point to Eurycoma Longifolia as a possibly herbal testosterone optimizer.
AVENA SATIVA (OAT BRAN):
Avena Sativa, also known as the common oat, is claimed by supplement companies to boost free testosterone levels via blocking the action of sex hormone binding globulin (SHBG). SHBG, as the name implies, is a protein which binds to the circulating sex hormones in the blood, preventing them from entering into cells and carrying out their functions. It is generally believed that about 98% of our sex hormones are bound by SHBG, leaving about 2% to carry out their functions. This explains why supplement companies are so intent on finding a miracle SHBG blocker that could “free up” all that extra testosterone! SHBG in humans have been shown to be positively correlated with estradiol (estrogen) and negatively correlated with testosterone and insulin. Indeed, while SHBG technically binds both testosterone and estrogen, it appears to have a much stronger affinity for testosterone than estrogen (about 3 times greater), meaning lowering SHBG would raise testosterone relative to estrogen. Unfortunately, while claims by supplements companies that Avena Sativa effectively blocks SHBG levels are pervasive, the scientific evidence is entirely non-existent. It would appear that this is one ingredient that is completely based on hype, and while the concept is enticing, we cannot accept this ingredient as a valid addition to the formula.
BLACK COHOSH (CIMICIFUGA RACEMOSA):
Cimicifuga Racemosa has been marketed as a pro-estrogenic supplement (not towards bodybuilders/athletes), but in fact recent studies have revealed that the opposite may be true. A 2002 in vitro study published in the Journal of Steroid Biochemistry and Molecular Biology” found that CR extract possessed anti-estrogen properties. Furthermore, a 2002 study showed that CR extract further enhanced the anti-estrogenic effects of tamoxifen (Nolvadex) of women with breast cancer. However, the current evidence for CR as an estrogen blocker is solely based on an in vitro study and just one human study that tested it affect when combined with a prescription estrogen blocker. No studies have been done on male humans to test the effect of CR extract (alone) on estrogen so we cannot say for sure if it has this effect or not.
34-divanillyltetrahydrofuran is the “active ingredient” in Stinging Nettle extract, which you may have come across in several other supplements aimed at boosting testosterone levels. The story with Stinging Nettle, and therefore 34-divanillyltetrahydrofuran is essentially the same as Avena Sativa. It is claimed (by supplement companies) that 34-divanillyltetrahydrofuran binds to SHBG, preventing SHBG from binding to the sex hormones. The effect would be increased free testosterone (emphasis on “would be”). As of now, there are only in vitro studies to suggest this effect, and while these studies have shown promise, we simply cannot accept an in vitro study as fact and must view them as a basis for further in vivo studies.
Diindolylmethane (DIM) is a byproduct created during the digestion of Indole-3-Carbinol (found in vegetables such as Broccoli). Similarly to Cimicifuga Racemosa, Diindolylmethane (DIM) has been shown to inhibit estrogen in women with breast cancer, but DIM is tricky when it comes to its effects on estrogen. In low doses, DIM has been shown to act as an aromatase inhibitor (anti-estrogen). Aromatase is the enzyme responsible for the conversion of testosterone to estrogen. By blocking the action of this enzyme, less testosterone is converted into estrogen, and the result is increased levels of testosterone relative to estrogen. A 2011 study found that, when given to subjects at a dose of 300mg daily for 14 days, DIM produced anti-estrogenic effects. Under different circumstances however, DIM has shown the opposite, meaning it actually has the capacity to increase estrogen. So, rather than labeling DIM as pro-estrogen or anti-estrogen, it should be considered an estrogen modulator (meaning it has the ability to alter levels of estrogen one way or another). In order to understand how this actually works, we need to back up and clear a few things up. First, the term “estrogen” is actually an umbrella term for a family of compounds. The members of this family are all different, and therefore have different functions and effects in the body. The types body builders and cancer patients alike hate, reffered to as “bad estrogens”, are 16a-hydroxyestrogens and 4-hydroxyestrogens. When we use the term “good estrogen” we are referring to 2-hydroxyestrogens. DIM appears to increase the level of 2-hydroxyestrogens, relative to the other types which results in less of an “estrogen-like” effect, while still technically increasing overall estrogen.
Piperine is the active component of Black Pepper Extract. In several studies, black pepper extract, when combined with other supplements, has increased the absorption of those supplements (as measured by plasma levels). The active ingredient responsible for this increased bioavailability is known as Peperine. While we can’t say with any certainty that Peperine enhances the bioavailability of ALL other compounds, it does have a well-established track record when it comes to vitamins, minerals, and amino acids (including BCAAs).
Zinc is required for the conversion of cholesterol (and other lipids) into sex hormones, as well as the existence of androgen receptors, as evidenced in a 1996 study, in which rats fed a zinc deficient diet experienced a decrease in androgen receptor sites and an increase in estrogen receptor sites. So while Zinc deficiency can certainly result in low testosterone, there is no evidence indicating that supplemental Zinc can increase Testosterone above normal. In fact, there is only evidence to the contrary. A 2009 study, published in the “European Journal of Clinical Nutrition”, concluded that zinc (ZMA) supplementation had no influence on serum testosterone levels in non-zinc deficient men. A similar failure to influence testosterone via zinc supplementation was seen in a 2011 study, the subjects of which were trained cyclists who consumed sufficient dietary zinc. However, a 2005 study, the subjects of which were wrestlers, demonstrated that zinc supplementation was able to attenuate exercise-induced declines in testosterone levels. The evidence is quite clear: Zinc supplementation will not increase testosterone above baseline in healthy, non-zinc deficient humans, but can be effective for maintaining consistent testosterone levels.
THE BOTTOM LINE:
For all intents and purposes, Androbolix XL is exactly the same as Androbolix 300, and is not a particularly effective Testosterone booster. There may be certain ingredients that can optimize Testosterone in men with abnormally low Testosterone levels, but there are no ingredients that have been shown to outright increase Testosterone levels in already healthy men.
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