The Most-Studied Testosterone Booster

The Most-Studied Testosterone Booster

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The Myth is Now Backed Up by Science

A new meta-study suggests that doctors may someday prescribe the herb, Eurycoma longifolia, to treat low testosterone. New info here.

Man, I love meta-studies.
Let me explain. In scientific research, there’s a credibility hierarchy. Down at the bottom, you’ve got case reports, opinion papers, letters to the editor, and probably miscellaneous Post-it Notes affixed to centrifuges. Just above them, you’ve got in vitro studies (those involving test tubes or Petri dishes) and animal studies.
I don’t mean to suggest that the above are crappola. It’s just that they inspire much less confidence than cross-sectional studies (where you collect data from many individuals from a single point in time), case-control studies (those that follow a group of subjects for a long period of time), and randomized control studies (where they divvy up participants into an experimental group or a control group).
None, however, inspire as much confidence as meta-studies, which are at the top of the heap – the grand poobah of scientific studies. They’re where they look at several clinical trials and merge the findings. And if these studies involve humans and they find some trends, they inspire a lot of confidence.
That’s why I’m so geeked out over this recently published meta-study on the effects of Eurycoma longifolia, aka Tongkat ali.
Here, I’ll just quote their conclusion so you can see why:

“This systematic review and meta-analysis of the literature supports the possible use of E. longifolia supplementation for enhancing testosterone production. Although more research is required before its use in clinical practice, this may represent a safe and promising therapeutic option, particularly for patients with hypogonadism.”

Yeah, that’s right – they’re suggesting that physicians may someday prescribe the mysterious herb to treat low testosterone.

The researchers, a group from South Africa, England, and the U.S., were aware of some of Eurycoma’s medical properties, such as improving athletic performance and increasing muscle mass while reducing fat. Likewise, they knew that the herb had long been used, at least in Malaysia, to treat male sexual dysfunction and infertility.
Based on these effects, their assumption was that Eurycoma did indeed raise testosterone levels, but they wanted proof. Hence their study. Their search of the databases rewarded them with 521 published articles involving the herb.
After ditching duplicates and those that involved animals, human females, in vitro studies, polyherbal formulations (those that tested the combined results of Eurycoma together with other herbs), and those that didn’t consider the herb’s effects on testosterone, they whittled it down to nine studies, five of which were highly regarded RCT studies (randomized control studies).
I know, you’re probably assuming these studies all involved decrepit old guys who had to have the Eurycoma snuck into them through laced prunes, but that wasn’t the case at all. While two of the studies used men between the ages of approximately 50 to 70 years old, three of them used men between the ages of 18 and 30, and another used men aged 40 to 59.
Seven of the studies reported that Eurycoma led to a significant increase in total testosterone levels, while two failed to show any improvement (one of these two stopped treatment after just three weeks, even though most experts suggest allowing at least four weeks for Eurycoma to take effect).
Some of the studies tracked other data in addition to total testosterone levels. Three reported a significant increase in free testosterone, too, while six found no concurrent rise in SHBG (steroid hormone binding globulins) levels. This is potentially important because SHBG, as the name implies, binds up testosterone, preventing it from doing the things you want it to.
Most of the studies used a dosage of 100 mg. to 200 mg. a day, although one used a hefty dose of 600 mg. a day, which resulted in increased testosterone levels in just 14 days instead of the usual three to four weeks seen with smaller doses.
Efficacy, however, relies on the concentration of various bioactive chemicals in Eurycoma, most of which lie in the roots of the plant. There’s a whole alphabet soup of them: quassinoids and quassinoid diterpenoids, canthin-6-one alkaloids, beta-carboline alkaloids, squalene derivatives, and triterpene-type tirucallane. It goes on and on, but it’s primarily the quassinoids that seem to have the greatest impact on testosterone levels.
These quassinoids are further classified as eurycomanones, eurycomanols, eurycomalactones, eurycolactones, eurycomanosol, and eurycomaosides, all of which are causing my spell check to stroke out.
Studies on these quassinoids in Eurycoma have shown ergogenic effects, including increased muscle size, strength, and endurance in cyclists. They also appear to have anti-estrogenic properties (thereby increasing testosterone levels further). Animal studies have shown that the herb causes a higher release of luteinizing hormone (LH) and follicle-stimulating hormone (FSH), both of which are intimately involved in coaxing the testicles to increase testosterone production.
“Bonus” effects include improved semen volume, semen motility, and erection hardness (the herb also inhibits something called rho kinases (ROCKs), which leads to stronger erections).
And lastly, the herb does something that might be hugely appealing to competitive athletes: Eurycoma administration doesn’t appear to affect the ratio between urinary testosterone glucuronide and epitestosterone glucuronide (T:E ratio), which is often used to determine testosterone doping in sports competitions.

Based on all the TV, internet, and radio ads for TRT, you’d think every other male in America is getting the needle, patch, or pellet, but that’s not the case. Current estimates are that only 10% of men with low testosterone (hypogonadism) are being treated with TRT.
This is largely because physicians still feel hinky about the treatment. It’s contraindicated in men who want to preserve fertility (TRT acts as a fairly effective male birth control unless other drugs are added into the mix), in addition to men with benign prostate hyperplasia (BPH) or prostate cancer, lower urinary tract symptoms, high PSA, obstructive sleep apnea, or a history of myocardial or cerebrovascular stroke.
Most of the Eurycoma studies, however, failed to show any significant side effects – no testicular shrinkage, no polycythemia (an increase in the number of red blood cells, possibly escalating the chances of stroke), no prostate enlargement, no sleep apnea, and no increases in liver enzymes (AST/ALT) that might indicate liver damage.
All this promising data led the researchers to hypothesize that Eurycoma longifolia might be used in clinical settings (e.g., doctor’s offices) as a possible treatment for hypogonadism, one that might have fewer side effects than conventional TRT.
Let’s be clear, though. No testosterone booster on the market will work as well as injecting testosterone cypionate or some other testosterone ester into your glute. Eurycoma longifolia, however, found in Biotest’s Alpha Male®, can be extremely effective in providing a modest boost in testosterone – enough to either bring you back up to normal or just give you a boost so that losing fat, building muscle, or making love is a little easier or more satisfying.
Each serving of Alpha Male® contains 100 mg. of Eurycoma longifolia extract (the recommended dosage is two servings a day), standardized to contain the highest amount possible of the two major, bio-active quassinoids, so you know you’re getting the good stuff.
Each serving of Alpha Male® also contains 20 mg. of forskolin carbonate and 500 mg. of Tribulus terrestris. This article is about Eurycoma, so I don’t want to sidetrack into discussions of these other herbs.
Suffice it to say, forskolin elevates levels of a cellular messenger known as cAMP, which also increases testosterone levels, and Tribulus terrestris is an herb that, among other things, enhances androgen receptor density in the brain and (possibly the muscles, too) so that any testosterone churned out, courtesy of Eurycoma and forskolin, has lot more spots in which to “park” and initiate their biochemical effects.
Together, the three compounds are the next best thing to an actual testosterone injection, at least for the hypogonadal male. Take 1-2 capsules in the morning on an empty stomach with 8 ounces of water. Repeat 6 to 8 hours later.
T Nation BiotestAlpha Male®
The Alpha Male formula boosts natural testosterone and energy with Malaysian Eurycoma longifolia and Bulgarian Tribulus terrestris.

Leisegang K et al. Eurycoma longifolia (Jack) Improves Serum Total Testosterone in Men: A Systematic Review and Meta-Analysis of Clinical Trials. Medicina (Kaunas). 2022 Aug 4;58(8):1047. PubMed.

I remember taking Eurycoma for a test drive years ago back when Tribex was the go-to T-booster from Biotest. It worked then, but I’m of course much happier with the Alpha Male formula these days.


Tribulus terrestris is an herb that, among other things, enhances androgen receptor density in the brain and (possibly the muscles, too)

Okay, that’s just darn cool info.


Well written (as usual), useful and on point. I concluded years ago that it worked, yes, a definite tingling down there. I just use the BulkSupplements Longjack Extract which makes it easy to do large doses–can’t beat the price.
It is sort of like “BASF” (regardless of where you get it) it doesn’t make T, it just makes the things that make T work better .

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