Ahhh, testosterone. It’s the hormone that makes dudes dudes. And if a dude with low testosterone levels can raise the available levels of this important hormone in his body he can expect such benefits as “improvement in libido and sexual function, bone density, muscle mass, body composition, mood, erythropoiesis, cognition, quality of life and cardiovascular disease.” (Bassil)

I was pointed to a supplement which aims to help men do just that: raise testosterone, naturally. It’s called T+ and it’s brought to you by Onnit. I’ve heard that it’s being promoted by some people affiliated with the UFC but I didn’t look into it. To be honest, I wanted to know as little as possible about the marketing behind the product so I could give an objective review of the ingredients.

Disclaimer: I have not tried this product, nor will I. For those of you who will say I can’t possibly review a product without trying it you might as well leave right now. This is not a review of my experience with the product (even if it was, my experience may or may not lend you useful information) but instead a review of the evidence in support of the ingredients and a discussion of how the product might work and on whom.

The short answer for those who don’t want to read all the mumbo jumbo: This product may help raise testosterone levels in hypogonadal men (low testosterone) but probably won’t do much for men with healthy testosterone levels. It more likely will increase sex drive (mental) unrelated to a rise in testosterone levels, which is a great benefit if you need it. It may also increase sperm count and sperm motility, increasing fertility. Cool if you need it, possibly very not cool if you don’t.

Label Candy

As you’ll see below in the Performance Blend section, supplement companies often group ingredients together and give the blend a name, so they don’t have to list how much of each ingredient is in the product, only the amount of the entire blend. This might be an attempt to keep their recipe a secret, but mostly it just hides the uselessness of the ingredients due to the quantities used in the product. I call this label candy. They put a bunch of words on the label to make unsuspecting and uneducated buyers (not meant as a put-down) think the product is kick-ass when most of those ingredients aren’t in the product in amounts that make them effective.

T+ by Onnit: The ingredients and the evidence for them

This product consists of three main blends, two of which I’ll be discussing.

Onnit Testo Blend (3.525 grams)

Magnesium aspartic acid, mucuna, Longjack Root, Nettle Root.

Magnesium aspartic acid

There are two papers given in support of the use of magnesium aspartic acid. Cinar et al investigated the effects of exhaustive exercise and magnesium supplementation on testosterone levels. Subjects were assigned to one of three groups: sedentary + 10mg/kg magnesium, active + 10mg/kg magnesium, active with no supplement for weeks duration. Activity was 90-120 minutes of tae kwon do 5 days/week. A rise was seen in each group in free and total testosterone from before exhaustive exercise to after, as well as from before supplementation to after. A larger increase in each was seen in the exercise + no supplement group as compared to the sedentary + supplement group, not surprisingly. The only conclusion I can draw from this research is that exhaustive exercise raises free and total testosterone more effectively than magnesium aspartic acid. Interestingly, the authors focus on the fact that group 2 (exercise + supplement) had the highest levels of testosterone at the end and that they saw the highest increase in total testosterone as a result of exhaustion, rather than pointing out that similar increases were seen in group 3 (exercise + no supplement) and in fact group 3 had a larger increase in FREE testosterone after exhaustion.

Topo et al gave men 3.12g/day of sodium D-aspartate for 12 days and measured the response of leutinizing hormone* (LH) and testosterone.  Both LH and testosterone increased significantly in 20 out of 23 subjects after 12 days. Cool! FYI, T levels rose from 4.5 to 6.4 ng/ml (450 to 640 ng/dl – more common units) which is nothing to scoff at. Nothing at which to scoff? Meh, grammar… What’s interesting is that they noted this response in 20/23 subjects. I’d love to know why it didn’t work in the other 3 subjects.

*leutinizing hormone is secreted by the anterior pituitary gland and stimulates testosterone production in the testes.

Mucuna Pruriens

Shukla et al investigated the effects of M Pruriens (5g/day) on infertile men and found an increase in LH, FSH, T and decreases in prolactin and FSH. The rises in testosterone were on the order of 100-150 ng/dl of the means. I must reiterate, this effect is seen in infertile, hypogonadal men.

So far, the research is telling us we need between .75 grams (assumed by 10 mg/kg body weight) and 3.12 grams per day of Magnesium aspartic acid, and 5 grams of M Pruriens per day, to achieve desired effects. We’re already over our 3.525 grams of the blend.

Nettle Root

There are two papers listed in support of this ingredient. One is a paper by Lopatkin, et al describing the benefits of plant compounds on lower urinary tract infections and their association with BPH (benign prostatic hypertrophy). Not one mention is made in regards to sex hormone binding globulin (SHBG) in the entire paper, which is why this ingredient is included in T+.  The authors of this paper refer us to others’ work for the mechanism of action, but I’m unable to get full text of the referenced article. In the UTI trial, a blend is used which includes 120 mg urtica root extract (nettle). I’ll give the benefit of the doubt here and say that nettle root’s effects on BPH are through, at least in part, binding to SHBG.

I also was unable to access the 2nd study referenced on the Onnit website for nettle root, but found other work by the same group of German scientists. It seems there is some plausible evidence for the action of nettle root binding to SHBG. (Schottner)

Longjack Root

Tambi, et al investigated the effects of 200 mg eurycoma longifolia in late-onset hypogonadal men in 2011. Of 320, only 76 men completed the treatment and follow-ups and only these men were included in the data analysis. This is strange, since reasons for the others’ departure are not given – one could assume regular attrition or a lack of adherence due to poor response to the supplement. In the 76 men who completed the protocol, testosterone rose from mean 5.66 to 8.31 nmol/L, which is statistically significant but leaves them still on the lower end of the recommended range.

Ismail et al, in 2012, studied 300mg eurycoma longifolia’s effects in healthy men on testosterone, IGF-1, SHBG, DHEAS levels as well as a host of sexual performance/libido questionnaire answers, physical fitness and body fat changes. No changes were seen in any of the hormones, physical fitness tests or in body fat %. Whoops! The questionnaires did show some positive outcomes in libido, sexual interest, and erectile function. Cool! But keep in mind this is not from a boost in testosterone.

As you can see, the amount in the blend (3.525 grams) falls short of being able to include each ingredient in the quantities found in the evidence. This doesn’t mean Onnit hasn’t done a ton of R&D and found lesser levels of these ingredients to be effective, especially in combination, but no mention of such is made on their website.

Omni Performo Blend (1.7 grams)

BCAA, beta-alanine, glutamine


Branched-chain amino acids are well-supported for their ameliorating effects on exercise-induced muscle soreness – at a dose of about 5g/day or 5g/exercise session. Onnit T+ has a whopping 750 mg of BCAA. You’ll have to forgive my skepticism, but I doubt this will result in a noticeable effect in the user. In case you don’t understand why, 750 mg is equal to 0.75 grams – as compared to the 5g effective dose mentioned above. FYI, I’m refraining from using the f-word and lots of LOLs right now. The paper referenced in support of BCAA is a short review – each study within uses at least 3 grams of BCAA to achieve its desired effect. (Da Luz)

Let’s back up. The Omni Performo Blend totals 1700 mg, or 1.7 grams. It includes beta-alanine, BCAA, and glutamine, in that order. In a proprietary blend, the ingredients are announced on the label in order of their weight, highest to lowest. Can you see what I’m saying?


The paper used in support of beta-alanine – which has enough support in certain cases – focuses solely on its effect to improve punch force and frequency in an amateur boxing match. If they’re going after the fighting market, this makes sense, right? Sure, except that researchers used 1.5g dose… 4 times/day. Whoops. That’s 6 grams of beta-alanine to achieve the desired effect in the paper and somewhere between .75 and .95 grams in the supplement. (1.7 g in the blend minus .75 g of BCAA and leaving wiggle room for glutamine) I’m showing some serious self-control here, people. No f-bombs or anything signifying my outrage. (


The makers of T+ don’t bother listing any references for glutamine, but I found one from 2011. In this study, glutamine was responsible for attenuating muscle soreness and maintaining peak torque values during knee extension exercise after an exhaustive eccentric exercise bout. (Street) Great! So, how much did the researchers use? .3g/kg, or an average of about 25 grams per participant per day. LOL! I guess there isn’t that much in the Performo blend…

Wrap it up!

Okay, there is also a blend geared toward counter-acting estrogen, but I’m not going to go into that. For one, I don’t have the energy for it right now. The other reason being that estrogen isn’t the worst thing ever so I’m not sure blocking its creation is even a good thing – this is very situation/patient specific. So, I’m skipping that part of the supplement and I feel okay about it, since I think we learned enough about the product already.

To anyone who may want to try this product, I highly encourage you to get before and after blood tests done. First, your initial blood work might reveal that a product like this is unnecessary for you and second, you will know for sure what affects the product has on your actual hormone levels. Measure LH, FSH, T, Free T, SHBG and maybe prolactin. I use LabsMD.com to order blood work and have had nothing but good experiences thus far.

All-in-all, I don’t think this is a bad product – at least at its core. I think the psychological affects of increased libido and sexual interest as well as possible physiological effects, depending on your starting point, of raised testosterone and other hormonal effects are important and could benefit the end-user. But again, for majority of healthy men the rise in testosterone is unlikely based on the evidence. What bothers me most is the performance blend and it bothers me enough to turn me off to the product. If I were looking to boost T or to increase libido I would look at some of the active ingredients by themselves and choose the ones with the best evidence. This would most likely be much more cost effective as well.

As always, intelligent comments and questions (maybe even a critique) are always welcomed.


Bassil, N., Alkaade, S., & Morley, J. E. (2009). The benefits and risks of testosterone replacement therapy: a review. Therapeutics and clinical risk management, 5(3), 427–48. Retrieved from http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=2701485&tool=pmcentrez&rendertype=abstract

Cinar, V., Polat, Y., Baltaci, A. K., & Mogulkoc, R. (2011). Effects of magnesium supplementation on testosterone levels of athletes and sedentary subjects at rest and after exhaustion. Biological trace element research, 140(1), 18–23. doi:10.1007/s12011-010-8676-3

Da Luz, C. R., Nicastro, H., Zanchi, N. E., Chaves, D. F., & Lancha, A. H. (2011). Potential therapeutic effects of branched-chain amino acids supplementation on resistance exercise-based muscle damage in humans. Journal of the International Society of Sports Nutrition, 8(1), 23. doi:10.1186/1550-2783-8-23

Donovan, T., et al., beta-alanine improves punch force and frequency in amateur boxers during a simulated contest.International journal of sport nutrition and exercise metabolism, 2012. 22(5): p. 331-7.

Ismail, S. B., Wan Mohammad, W. M. Z., George, A., Nik Hussain, N. H., Musthapa Kamal, Z. M., & Liske, E. (2012). Randomized Clinical Trial on the Use of PHYSTA Freeze-Dried Water Extract of Eurycoma longifolia for the Improvement of Quality of Life and Sexual Well-Being in Men. Evidence-based complementary and alternative medicine : eCAM, 2012, 429268. doi:10.1155/2012/429268

Lopatkin, N., Sivkov, a, Walther, C., Schläfke, S., Medvedev, a, Avdeichuk, J., Golubev, G., et al. (2005). Long-term efficacy and safety of a combination of sabal and urtica extract for lower urinary tract symptoms–a placebo-controlled, double-blind, multicenter trial. World journal of urology, 23(2), 139–46. doi:10.1007/s00345-005-0501-9

Schöttner, M., Spiteller, G., & Gansser, D. (1998). Lignans interfering with 5 alpha-dihydrotestosterone binding to human sex hormone-binding globulin. Journal of natural products, 61(1), 119–21. doi:10.1021/np9701743

Shukla, K. K., Mahdi, A. A., Ahmad, M. K., Shankhwar, S. N., Rajender, S., & Jaiswar, S. P. (2009). Mucuna pruriens improves male fertility by its action on the hypothalamus-pituitary-gonadal axis. Fertility and sterility, 92(6), 1934–40. doi:10.1016/j.fertnstert.2008.09.045

Street, B., Byrne, C., & Eston, R. (2011). Glutamine Supplementation in Recovery From Eccentric Exercise Attenuates Strength Loss and Muscle Soreness. Journal of Exercise Science & Fitness, 9(2), 116–122. doi:10.1016/S1728-869X(12)60007-0

Tambi, M. I. B. M., Imran, M. K., & Henkel, R. R. (2012). Standardised water-soluble extract of Eurycoma longifolia, Tongkat ali, as testosterone booster for managing men with late-onset hypogonadism? Andrologia, 44 Suppl 1, 226–30. doi:10.1111/j.1439-0272.2011.01168.x

Topo, E., Soricelli, A., D’Aniello, A., Ronsini, S., & D’Aniello, G. (2009). The role and molecular mechanism of D-aspartic acid in the release and synthesis of LH and testosterone in humans and rats. Reproductive biology and endocrinology : RB&E, 7, 120. doi:10.1186/1477-7827-7-120

An all-natural testosterone booster?
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