- 1. Introduction
- 2. Production of testosterone, GH and IGF-1 in males
- 3. Physiological role of DAA in males
- 4. Primary benefits of DAA supplementation in males
- 5. Possible side effects of DAA supplementation in males
- 6. Who should or should not consider using DAA
- 7. How to take DAA
- 8. Recommended Dosing
- 9. DAA FAQs
- About the role of DAA in normal testosterone production in males.
- What the primary benefits of DAA supplementation can be for males.
- Who should consider DAA supplementation.
- About the possible side effects associated with DAA usage.
- How to take DAA supplements.
D-aspartic acid (DAA) is an amino acid and is the enantiomer of L-aspartic acid (LAA), which is one of the 26 amino acids that make up proteins. DAA is found in the human body and various foods, but in much smaller amounts that its counterpart LAA; despite its scarceness, DAA appears to play a significant role in the neuroendocrine system of vertebrates, especially with regards to production of male sex hormones and growth factors.
Therefore, in recent years, supplementation with DAA has garnered interest for athletic performance enhancement. While DAA may certainly elevate endogenous production of hormones like testosterone, growth hormone (GH), and insulin-like growth factor 1 (IGF-1), don’t expect supplementation with this supplement to produce anabolic steroid-like results.
This isn’t to say you can’t benefit from DAA supplementation (otherwise this guide would be useless), but that anabolic androgenic steroids, when taken for performance and physique enhancement, are generally administered so as to elevate anabolic hormones to levels well beyond normal physiological ranges. DAA may certainly elevate your endogenous production of various anabolic hormones, but not to supraphysiological levels that would typically be achieved through administration of anabolic steroids.
Note: Aspartic acid and its conjugate base, aspartate, are biologically identical in many regards so the notation ”DAA” used herein refers to both moieties.
Production of testosterone, GH and IGF-1 in males
The primary male sex hormone produced by the testes is testosterone. The production of testosterone (and many other hormones) is controlled by an intricate feedback system between the hypothalamus, pituitary gland, the liver and testes.
When physiological concentrations of testosterone drop to low levels, the hypothalamus generates gonadotropin releasing hormone (GnRH) which is then detected by the pituitary gland which secretes luteinizing hormone (LH), a hormone which when detected by the testes stimulates the production of testosterone.
Moreover, GH and IGF-1 are also regulated by this same axis (i.e. the hypothalamus-pituitary-gonads pathway). When the hypothalamus produces growth hormone releasing hormone (GHRH) the pituitary releases GH in a pulsatile fashion. GH then goes on to signal the liver to produce IGF-1.
With this basic understanding of how these hormones are produced in males, let’s take a look at how DAA can impact their production.
Physiological role of DAA in males
Many animal studies have shown that DAA appears to act on the hypothalamus and stimulate the secretion of both GnRH and GHRH, therefore acting downstream to ultimately produce testosterone, GH, and IGF-1. [1,2,3]
Another curious finding is that DAA may actually also stimulate the production of thyroid hormones, specifically T4 and T3.  It is hypothesized that this occurs from the oxidation of DAA in the thyroid gland to hydrogen peroxide, an essential precursor for the iodination of tyrosyl moieties (which are necessary in the synthesis of thyroid hormones).
However, keep in mind that animal studies don’t necessarily translate completely to how compounds will act on humans. The unfortunate case for DAA is that human studies on DAA intervention remain scarce (and the one study cited herein appears to be underwhelming). 
This doesn’t mean that DAA is bunk though since that was a short-term study, utilized a minimal dose of DAA (3g per day) and had a rather small sample size.
Anecdotal evidence has been positive in many individuals who supplement with it so further studies will certainly be informative. It may just take a larger dose for certain individuals based on how they respond. Factors to consider that could alter the response to DAA include age, endocrine health, training status, diet, etc.
Primary benefits of DAA supplementation in males
At the time of composing this guide many of these benefits are based on anecdotes, animal studies, and suppositions. As noted earlier, the effects of DAA supplementation will be variable from one person to the next and experimentation with dose, frequency, and duration of use will likely be necessary.
- Elevates physiological levels of testosterone, growth hormone, and insulin-like growth factor 1—all of which have positive ramifications on athletic and sexual performance
- May act to increase thyroid hormone production (T4 and T3) via production of hydrogen peroxide from oxidation of DAA in the thyroid gland—elevating levels of thyroid hormones ultimately will increase metabolic rate
You may be thinking, “Only two bullet points of benefits?” But if you read into these benefits closely, you’ll realize that they’re significant, if not understated. Testosterone, GH and IGF-1 all have implications on speeding up recovery time from exhaustive resistance training, enhancing muscle growth, increasing work capacity, enhancing libido, and many other positive factors for the active individual.
Possible side effects of DAA supplementation in males
As was discussed in the preamble, the good thing about DAA is that it presents a natural route to increase endogenous production of the hormones discussed herein. This is to say that you’re avoiding use of potentially harmful pharmaceutical compounds like anabolic steroids and prohormones, which can significantly affect your endocrine system when taken in large doses and for excessive periods of time.
That being said, there are still a few side effects that could arise from the use of DAA since it may elevate levels of the aforementioned hormones and other metabolites:
- Increased dihydrotestosterone (DHT) levels which may cause hair loss and acne
- Increased estrogen levels (due to aromatization of testosterone) which may cause bloating, gynecomastia, prostate issues, and inhibit libido. However, it should be noted that elevated estrogen side effects will be rare, if nonexistent, if you’re cycling your use of DAA as is recommended in this guide
Who should or should not consider using DAA
Many individuals may stand to benefit from DAA supplementation, but there are a few exceptions in which it is likely best to avoid use.
Consider using DAA if you are:
- Male, over 21 years of age, and have low-to-normal testosterone levels
- Looking for a natural route to elevate endogenous anabolic hormone production
- Have low libido and/or feel like your ability to recover from training has been lacking
- NOTE: It is wise to have your testosterone levels overseen by a licensed medical physician prior to and throughout your time supplementing with DAA
Avoid using DAA if you are:
- Female (mainly due to uncertainty of its effects at the time of writing this)
- Under 21 years of age and/or have elevated testosterone levels (hypergonadism)
- Dealing with excess levels of DHT and/or estrogen
- Dealing with hyperthyroidism since this would likely exacerbate the issue
How to take DAA
- It is best to cycle your use of DAA in a 2-3 week “on” period followed by 1-2 weeks “off” and then repeating the cycle
- Take your dose of DAA daily, mixed in liquid (if powder form), and with or without food
- Split your dose into morning and evening doses if you are taking 5+ grams per day (see dosing recommendations below)
- Start with the lower limit of 3g per day and assess your tolerance/results after one cycle
- It is suggested that a maximum dose of DAA be limited to 20 grams per day (which is actually quite high for most individuals)
- Most individuals will see a good response with 5-10 grams per day 
Q: I’m under 21 years of age but still have low testosterone levels, can I take DAA?
A: Before jumping into DAA supplementation it will be prudent to see your primary care physician (and possibly an endocrinologist) about your concerns to rule out possible hypogonadism or other endocrine issues.
Q: Do I need to take an aromatase inhibitor (AI) while using DAA?
A: An AI is not needed, but if you’re experiencing side effects of excessive estrogen production you should consider either stopping the DAA and/or adding in an AI.
Q: Will DAA shut down my body’s natural hormone production?
A: No, DAA actually works by essentially augmenting your endocrine system’s natural production, not by synthetic elevation of those hormones from exogenous hormone administration.
1) D'Aniello, A. (2007). D-Aspartic acid: an endogenous amino acid with an important neuroendocrine role. Brain research reviews, 53(2), 215-234.
2) D’ANIELLO, A. et. al. (2000). Occurrence of D-aspartic acid and N-methyl-D-aspartic acid in rat neuroendocrine tissues and their role in the modulation of luteinizing hormone and growth hormone release. The FASEB Journal, 14(5), 699-714.
3) Di Fiore, M. M., Assisi, L., Botte, V., & D'Aniello, A. (1998). D-Aspartic acid is implicated in the control of testosterone production by the vertebrate gonad. Studies on the female green frog, Rana esculenta. Journal of endocrinology,157(2), 199-207.
4) Willoughby, D. S., & Leutholtz, B. (2013). 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. Nutrition Research, 33(10), 803-810.
5) Topo, E., Fisher, G., Sorricelli, A., Errico, F., Usiello, A., & D'Aniello, A. (2010). Thyroid Hormones and D‐Aspartic Acid, D‐Aspartate Oxidase, D‐Aspartate Racemase, H2O2, and ROS in Rats and Mice. Chemistry & biodiversity, 7(6), 1467-1478.