In this vid, I discuss the popular “Testosterone booster” supplement D-Aspartic Acid (DAA) and update my opinions of this general category of supplements. Note the 2015 study below  published  found at higher doses, it actually lowered testosterone. The 2016 study, found no impact on T levels, but improvements in strength on squats and a positive “trend” on the bench press.

Study mentioned in the vid:
D-Aspartic acid supplementation combined with 28 days of heavy resistance training has no effect on body composition, muscle strength, and serum hormones associated with the hypothalamo-pituitary-gonadal axis in resistance-trained men

This new study found no impact on T or body composition, but did find a statistically significant effect on strength. The study was short and given more time, it’s possible there would be improvements  in body comp (as being able to lift more weight in a given lift usually leads to positive changes in body comp) but it was a short lived and small study, so no real conclusions can be made from the results, other than DAA appears to have increased lifts in the short time period. It’s also possible, especially when viewing it in the larger picture of other studies, the DAA was not responsible for the effects found in the study and it was due to some confounding variables they didn’t account for.

Effect of Aspartate Supplementation on Athletic Performance and Testosterone Levels in Young Men

April 2016 The FASEB Journal vol. 30 no. 1 Supplement 898.12

D-aspartic acid has been suggested to enhance athletic performance by regulating the hypothalamus-pituitary-gonadal axis by increasing plasma testosterone. Aspartate supplementation may be useful to increase testosterone for individuals with low plasma testosterone due to aging and other conditions.

PURPOSE: To determine the effect of D-aspartic acid supplementation on athletic performance and testosterone production in young male athletes.

METHODS: After screening for ACSM low risk, 15 healthy male athletes (average age = 22y, body weight = 79.1 kg and body fat = 9.2%) were randomized to two groups for supplementation using a double blinded parallel arm experimental design. They ingested either 3 grams of d-aspartic acid (Aspartate, n=9) or a Placebo (n=6) for 14 days supplied in capsule form. Subjects recorded and replicated previous 3 day diets prior to testing. Physical assessments were performed prior to and after supplementation included a peak VO2 test by cycle ergometer, 1 maximal repetition bench press and 1 maximal repetition squat (average values ±SD before supplementation were 41.7 ±6.4 ml/kg/min, 117.9 ±11.1 kg and 151.7 ±19.0 kg, respectively).

RESULTS: The Aspartate group had a positive trend in performance during the 1 maximal repetition bench press by 3.5 ±6.8kg (average ±SEM, p=0.06) and a significant increase in the 1 maximal repetition squat by 8.5 ±10.5kg (average ±SEM, p=0.013). No change in performance measures were observed in the Placebo group. There was no change in testosterone levels in the control group: Pre-731.2± 70.4 ng/dL, Post-733.7± 77.8ng/dL (average±SEM) or in the experimental group: Pre-720.56±79.9ng/dL, Post-719.8±72.8ng/dL (average±SEM). Body composition did not change for either group.

CONCLUSION: D-aspartic acid supplementation may lead to improved acute skeletal muscle synthesis improving upper and lower body muscle performance. D-Aspartic Acid supplementation does not have a significant effect on testosterone levels and the time point observed.

Abstract HERE

2015 study and additional comments:

The criticism of some to prior studies was that it was possible higher doses were needed to impact T levels in younger resistance trained men. This study just out below found higher doses actually decreased testosterone! And the study was done on the appropriate population, resistance trained men, although they didn’t test the impact on TT and FT on strength or LBM as the prior study above did. The two studies combined however, do not paint a good picture for DAA in my view. This only lowers, my already low opinion of “T boosters” as a category of supplements…
Three and six grams supplementation of d-aspartic acid in resistance trained men
Journal of the International Society of Sports Nutrition 2015, 12:15
Although abundant research has investigated the hormonal effects of d-aspartic acid in rat models, to date there is limited research on humans. Previous research has demonstrated increased total testosterone levels in sedentary men and no significant changes in hormonal levels in resistance trained men. It was hypothesised that a higher dosage may be required for experienced lifters, thus this study investigated the effects of two different dosages of d-aspartic acid on basal hormonal levels in resistance trained men and explored responsiveness to d-aspartic acid based on initial testosterone levels.
Twenty-four males, with a minimum of two years’ experience in resistance training, (age, 24.5 ± 3.2 y; training experience, 3.4 ± 1.4 y; height, 178.5 ± 6.5 cm; weight, 84.7 ± 7.2 kg; bench press 1-RM, 105.3 ± 15.2 kg) were randomised into one of three groups: 6 g.d−1 plain flour (D0); 3 g.d−1 of d-aspartic acid (D3); and 6 g.d−1 of d-aspartic acid (D6). Participants performed a two-week washout period, training four days per week. This continued through the experimental period (14 days), with participants consuming the supplement in the morning. Serum was analysed for levels of testosterone, estradiol, sex hormone binding globulin, albumin and free testosterone was determined by calculation.
D-aspartic acid supplementation revealed no main effect for group in: estradiol; sex-hormone-binding-globulin; and albumin. Total testosterone was significantly reduced in D6 (P = 0.03). Analysis of free testosterone showed that D6 was significantly reduced as compared to D0 (P = 0.005), but not significantly different to D3. Analysis did not reveal any significant differences between D3 and D0. No significant correlation between initial total testosterone levels and responsiveness to d-aspartic acid was observed (r = 0.10, P = 0.70).
The present study demonstrated that a daily dose of six grams of d-aspartic acid decreased levels of total testosterone and free testosterone (D6), without any concurrent change in other hormones measured. Three grams of d-aspartic acid had no significant effect on either testosterone markers. It is currently unknown what effect this reduction in testosterone will have on strength and hypertrophy gains.
Full paper HERE

  1. steve 10 years ago

    Testosterone boosters for young men who are already blasting with testosterone? When the amount of testosterone has started to decrease( with aging) how does it shape up there? I would think that there would be more support for boosters then and a better chance for them to work. I would love to see some tests run on 50 + year olds:)

    • Liam 10 years ago

      Maybe that’s me…just hit 50…see my comment below…Liam

    • Author
      Will Brink 10 years ago

      Wish I had a good answer for you on that, but I don’t. Getting T levels up for say men over 40 with reduced T levels looking for in impact on say libido is a different issue than younger guys with high healthy T levels wanting to get bigger and stronger. There’s not a great deal of good data to support that either, and results tend to be all over the place as things like mood and libido are difficult to test objectively vs say if your muscle mass changes.
      I’d say it’s yet another area those companies looking to sell to that growing market (men over 40, 50, 60, etc) looking to improve libido and mood and such should fund real research to test their products for that use.

      • Dan Bialik 8 years ago

        I am 58 and taking 3 grams of DAA in the morning. Mostly trying to keep strength/muscle mass up. I have gained a few pounds. (could just be getting fat) 🙂 Will comment again in a few weeks.

    • Stu Phillips 10 years ago

      Lots of drugs work (Androgel, Axiron). You need a scrip, but under a physician’s care you’d be good to go. Beware though, these drugs do raise risk for heart disease and possible other reproductive tissue cancers (see the history of estrogen replacement in women for a clue where this might go).

  2. Liam 10 years ago

    Will, great article as usual. I’m on the fence so to speak about test boosters. My whole supplement outlook is “what” is it supposed to do, and “what” is it doing for me. Since starting on test boosters my progress T the gym has remained basically the same as without them. But, my sex drive is through the roof. My wife has never had a days peace as is. I feel like I’m back in high school. I have ruled out the placebo effect because all I was expecting was a gain/loss in the gym…but i suddenly realized ” me so horny”..go figure…best wishes, keep up the great advice,Liam

    • Author
      Will Brink 10 years ago

      If you feel it’s working in that area, all good. It may be acting through other mechanisms unrelated to T levels per se (see article linked in vid for more details on that) or could indeed placebo effects, or simply unrelated to the product, or something else, like a spiked product, etc.
      You can’t really rule out placebo any time you’re working with what’s subjective and anecdotal responses no matter how much we think otherwise.

  3. Jeffrey. Duplechain 10 years ago

    Is there anything out there that does boost testosterone levels safely?

    • Author
      Will Brink 10 years ago

      Read article linked in vid for more info

  4. brian 9 years ago

    Pat Arnold would disagree and I believe had done extensive ‘in house’ testing with labs before he went ahead and sold it. Correct me if I am wrong but I recall him saying even in the negative study (perhaps this one) there was still a significant boost in LH.
    Perhaps DAA only works for men with Low-T?

    • Author
      Will Brink 9 years ago

      I don’t think Pat would disagree, but you’ll have to ask him. I don’t know of any in house testing he did, but read article linked in vid for my take on “T Boosters” as a category for more info on that topic.
      Maybe DAA may work better for men with already low T, but we need more real data examining that one to make any solid conclusions there.

      • brian 9 years ago

        I have a hard time thinking Pat would sell Testo Force if he agreed with you on this. I don’t know him personally but he seems to be one of the few only selling what he believes in.

    • Gene 9 years ago

      The sample size was exceedingly small. N=8 per condition. Also , as others have said, this study was done on young, weight trained men. Why would one expect a significant boot in T from these individuals? Percent increase in any measure (in this case T) would be small if the intervention does not have a tremendous effect. Example: Almost impossible to increase IQ score on any IQ test for people over one standard deviation above the mean with training on cognitive skills. However, the increase is scores on IQ tests can be meaningful for individual at the mean or slightly below. One should not extrapolate the results of the above experiment to groups other than the groups that mirror the sample. Very dab scientific practice..

      • Author
        Will Brink 9 years ago

        The vast majority of users of these products are young guys with healthy T levels that want to make it higher to build muscle and increase strength. This and the prior study looked at the most applicable users of these products. Science plods along, and it’s possible that a group of researchers may decide to test the hypothesis that studies find it does not work as intended in young healthy resistance trained males, but might in older men with sub lower T levels, etc. As it stands now, there’s no particular reason to think it would prove effective in that latter population compared to the former, and similar essentially all the supps in this category, best avoided ’till legit research exists.

  5. DANIEL J 9 years ago

    Bd certifed/fellowship-trained orthopaedic surgeon/atty; trained/exercised, played competitive sports from grade school-college,military training/experience, etc.,etc. for approx 50 yrs…
    I think your site, along with the striking looking young woman’s seen here(whose name I don’t recall), provides excellent information. You are providing a great service.
    In my view, most(if not all…) of the supplement world is an ongoing fraudulent enterprise.
    Train hard, incorporate functional, multi-joint movements, rest/recover and eat properly=”the secret”……everything else is bullshit.

    • Author
      Will Brink 9 years ago

      There’s supplements worth using, many of which are covered here in articles and vds. Creatine for example is a no brainer. Yes, most look to magic pills and such vs. actually focusing on the real factors to success: good nutrition and smart training 🙂

  6. Chris 9 years ago

    Once again, thanks Will.
    What about the “combination” of ZMA? Does the same apply for this supplement. I notice that’s it’s oftend used and reccomended. Please assist?
    Keep the knowledge coming. PLEASE! Lot of wolves in sheep clothing out there.
    Chris D.

    • Joel 9 years ago


    • Author
      Will Brink 9 years ago

      Early studies suggested ZMA may help if you’re low in those minerals, later studies showed it didn’t help. I cover ZMA and many others in my Body Building Revealed Program and Sports Supplement Bible if interested in ZMA and most other supplements on the market.

  7. Kent Ingram 9 years ago

    Pardon me for being a little depressed, Will. I keep hoping a natural supplement will come along that will boost my T-levels, but none can make the muster, evidently. That leaves me, along with older guys like me, only one alternative, which is to spend money (if you have it) on a clinic that specializes in such things. Hopefully, any medical insurance one might have will cover at least a part of that treatment. If I sum up all your articles, I come to the conclusion that there’s no supplementation out there, presently, that can deliver on the promises of “natural” T-level boosting. I’m ambivalent about synthetic hormone replacement, but your studies have shown a reasonable safety record. Thanks for lifting the veil, once again!

  8. Glen Wheeler 9 years ago

    Great video.Thanks valuable to a 67 year old fitness buff.

  9. Joel 9 years ago

    Good work, Will…8 inches!

  10. Chas 9 years ago

    I’ve seen research over the years that shows that Aspartic Acid is a “excitatory neurotoxin” – thoughts?

  11. Roger 9 years ago

    Even though I was skeptical, I decided to try DAA since it was fairly inexpensive (I’m 49 years old). After 4 weeks of taking 3mg per day, I’ve noticed zero results. So I’d say that Will’s review is right on the money. But I’ll know for sure in a few days, as I had my annual physical a few days ago with a full panel of blood work taken. My testosterone level has been around 375 ng/ml the last few times I’ve had it checked over the past year, so I’ll know for sure if DAA had any effect whatsoever once the results from my latest test comes back next week. I’ll keep you posted…

  12. Author
    Will Brink 9 years ago

    See new study above folks!

  13. Peter 9 years ago

    Will, thanks for the information, and your honesty. There is just too much hype going on in this industry, and it’s nice to hear the truth. I always enjoy reading your articles.

  14. Matt 9 years ago

    Does it help ANYTHING in the aging male?

    • Author
      Will Brink 9 years ago

      Not that I’m aware of no.

  15. Robert Minshall 9 years ago

    I know you have endorsed and I use it quite a bit. Have you looked up D-aspartic acid on their site. It seems to contradict what this study found that you quoted above

    • Author
      Will Brink 9 years ago

      I don’t endorse per se, I endorse their Research Digest. That does mean I don’t like per se, but I don’ always agree with their assessment of some supplements. Finally, I don’t see how what’s on Examine contradicts what this recent, and the one before found. They made need to update their info to reflect this most recent study.

  16. Author
    Will Brink 8 years ago

    Multiple studies now find it’s not effective for increasing T period.

  17. gino v black 4 years ago

    will your right i used it for t wo months nothing happend & IAM STILL AS STRONG AS I WAS BEFORE I USEDE IT, YOU WRITE ARTICALS, THANKS

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