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“Does Nugenix Work”; does it boost testosterone

The latest “testosterone booster” to be touted in ads all over the Internet is called Nugenix. It’s manufactured for and marketed by GNC. The product’s marketers make the usual claims that are associated with all other ‘natural’ testosterone boosters, i.e.: Improved libido, more muscle mass, higher energy, better well-being… etc.

Sounds great, doesn’t it? But ‘does Nugenix work’; does it increase testosterone?

Nugenix-testosterone boosterWhile many of us in the muscle building world are familiar with the product’s ingredients and amplified claims that accompany them, those individuals in the market that this product’s advertising is targeting might not be quite as aware of the hype. Many are middle-aged to older men. They simply want to spike what they perceive as flagging energy and libido. A pill containing natural ingredients is the best way to do it. The appeal is simple: take the tablets, feel the energy and increased libido, watch the body fat go down, watch the muscles expand…  ‘Nirvana’; “who needs to work at this?”

That is… if Nugenix works. But does Nugenix work?

Let’s take an objective look at the ingredients to analyze that.

‘Does Nugenix Work?’ A look at the ingredients

Those asking the “does Nugenix work” question should first know what’s in the product and whether any of those individual ingredients have been shown to boost testosterone. The so-called main ingredient in Nugenix is listed as ‘Testofen™’, a proprietary extract from the Fenugreek plant. Along with this is the plant extract Tribulus Terrestris, an ingredient that’s long been hyped as a T-booster. The other ingredients listed are citrulline malate (an amino acid) along with 50 mg. of zinc and vitamins B6 and B12.

Obviously, the citrulline, zinc, and B-vitamin ingredients were merely included as support additives. They can be acquired in adequate amounts from either a well-balanced diet or a multi-vitamin/mineral supplement. Therefore, the claim of Nugenix being capable of raising natural testosterone is primarily based on the alleged power of ‘Testofen™’ and ‘Tribulus’ to spur more testosterone production.

I’ve already written my opinion of Tribulus right here, if you care to read it. If not, you can go with this summarization: both the objective and anecdotal evidence for that herb being effective at boosting testosterone in humans are not good.

This should raise good questions in the mind of any thinking person: If Testofen™ raises testosterone, why would Tribulus Terrestris need to be combined with it? Conversely, if Tribulus Terrestris ever had been effective, why would marketers need to jump on a newer claim of the same effects being derivable from the Fenugreek in Testofen™? This second question should be especially salient given that Tribulus Terrestris has been around as a supplement for a long time.

I often wonder stuff like that. The assumption we’re obviously supposed to buy into is that both these extracts have always done what’s claimed about them and that combining them makes them… well, reeeeally effective.

‘Does Nugenix Work’ translates to “Does Fenugreek Work”

With its supportive ingredients being unlikely to boost testosterone and the probable ineffectuality of Tribulus, Nugenix would need to rely on the Fenugreek extract to be effective. Thus, the question “does Nugenix work” is more a question of ‘does Fenugreek increase testosterone.’

There’s only one published study I’m aware of that claims a positive answer to that question. In fact, the study claims a finding of near doubling of ‘free testosterone’ – the bodily form of the hormone that will actually help build muscle, burn fat, and boost libido.  Only drawback – the study was not done independently; it was funded and performed by the company that trademarked and markets Testofen™. That makes objectivity a near impossibility.

BTW… ‘Free testosterone’ runs at about 2-3% of ‘total testosterone.’ So if you’ve got a test result for your ‘total T-levels’ being at, say… 500 ng./dL. , then your free testosterone would be (at best) around 15 ng./dL.

It so happens that the guys used in this study reportedly started with an average free testosterone level of 17.76. This was among 55 healthy male volunteer subjects ranging in age from 18-35. The said purpose of the eight-week study was to discover whether Testofen™ (fenugreek extract) safely increases free testosterone and/or decreases body fat. Of the subjects who completed the study, 29 received two doses of Testofen™ per day at 300 mg. per dose. The other 26 participants received a placebo.

What were the results? Huge Triceps

According to Gencor Pacific (the company behind the study – and product), not only did free T-levels almost double (98.81% increase), but body fat was also significantly reduced in the test group. This was purportedly indicated by a decrease in skinfold caliper measurement within these subjects without an accompanying drop in body weight.

Sounds great, doesn’t it? If you’d like to read the company’s PDF on the study, you can see it right here.

A 2009 study, however, showed a different result. This one, another double-blind test, was published here in the International Journal of Exercise Science and involved 45 male subjects, half of whom took 500 mg. of Fenugreek extract per day while the other half took a placebo for the eight week experiment. The subjects were all weight trained individuals and underwent a resistance training protocol during the study. This one showed no increase in testosterone (or any other tested hormone) and, in fact, only showed a slight decrease in DHT (dihydrotestosterone) in the group taking the fenugreek extract.

‘Does Nugenix Work’… and if so, how would it “work?”

If a product can naturally stimulate more testosterone production, there are a couple of ways by which it could work. That’s because male testosterone production happens through a loop feedback axis. When the hypothalamus in the brain detects blood testosterone levels as being too low, it sends a signal to the testes via lutienizing hormone (LH). It conversely reduces its output of LH when it gets readings that T-levels are adequate. If a substance could stimulate LH output, it could result in more testosterone. If a substance acts similarly to LH itself, thus directly stimulating the leydig cells in the testes, it could result in higher T-levels as well.

There’s an additional, indirect way that a substance could naturally raise testosterone levels. This would be by suppressing the antagonists of testosterone. There are two major ones to be aware of: estrogen and SHGB (Sex Hormone-Binding Globulin).  

Estrogen is created in the male body (in a form called ‘estradiol’) by way of an enzyme called aromatase. The aromatase converts some of the testosterone molecules into estradiol molecules. This is natural and normal as we guys designed to have some estrogen. When too much conversion takes place, however, estrogen can get too high and begin to fill the cell receptor sites where testosterone would otherwise reside. This can adversely affect testosterone levels because the estrogen filling these receptor sites often sends a ‘false signal’ to the hypothalamus – effectively convincing it that the sites possess testosterone and that T-levels are, therefore, adequate.

Bottom line: high estrogen equals lower testosterone. Thus, if a product can reduce estrogen directly, or it reduces aromatase, it could raise testosterone.


Sex Hormone-Binding Globulin (SHBG), on the other hand, is what directly controls how much ‘free testosterone’ is available. It is a glycoprotein that’s produced primarily in the liver and has 98% of ‘total testosterone’ “bound up” at any given time. Therefore, ‘free testosterone’ – which is the biologically active form that affects muscle, libido, body composition, energy levels, etc. – can be increased either directly or indirectly: It can be directly increased by reducing the amount of SHBG or it can be indirectly increased by raising the production of ‘total testosterone.’

BTW… higher estrogen levels have been shown to increase SHBG levels – another means by which excessive estrogen can lower testosterone.

Given those explanations, there are only a few ways in which Nugenix could work if the “does Nugenix work” question could be answered in the positive:

  • Directly stimulating the leydig cells to produce more testosterone
  • Stimulating more LH release which, in turn, stimulates the leydig cells
  • Reducing levels of estradiol in the body
  • Reducing SHBG levels in the body

Any one of these routes could lead to higher ‘free testosterone.’ If researchers had discovered their proprietary product could effectively double this small percentage of the hormone, you’d think they’d explain the means by which it occurred.

‘Does Nugenix Work’: Conclusion

Personally, if I were a betting man, I wouldn’t put a wager on Nugenix “working” to increase testosterone. And as recommendations go, I’d tell a guy wanting to raise his T-levels to shift his focus toward high workout intensity, reduced body fat, and better eating habits with an emphasis on more cruciferous vegetables.

However, I realize I’m a bit jaded in my long-ago experience in the dietary supplement-taking department.  Consequently, I’m open to any comments of anecdotal experience in using Nugenix; let us know what you think if you’ve used this product.

Your comments are appreciated.


Phil A

Hi Scott,

Thanks for the Nugenix article.

Would appreciate your opinion about IGF-1 aka Deer Velvet Antler Extract in boosting testosterone and muscle regenerative properties. Also T Bomb product from bodybuilding.com

From what I've heard about IGF-1 product is that it works better because it's not synthetic, like some products.

I'm mid 50's, was about 30 lbs overweight, lost a dozen so far and always played sports and was in shape, but never did the weights, didn't need to, but after the most recent 15 pounds, I started feeling bad, and diabetes runs in my family and was already diagnosed with low thyroid, on synthroid, but amount keeps getting higher and higher, so I quit because I felt the artificial thyroid hormone was suppressing my real thyroid production.

Another related question, was that you mentioned eating lots of 'cruciferous' vegetables, but they tend to work against the thyroid and I'm already low. I'm feeling better since I've been working out, eating better, but haven't had blood test to measure yet. Doesn't thyroid work together with other things to assist in increasing testosterone production?

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