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D-Aspartic Acid Benefits, Side Effects & Safety Information

Published: 13th May 2018. Last updated: 21th July 2019.

Shaun Ward MSc ANutr

Staff Writer


Introduction

D-aspartic acid, also commonly referred to as DAA, is one form of an amino acid called aspartic acid, with the other form being l-aspartic acid.

They are both have the same chemical formula, but their molecular structures are the reverse of one another.

D-aspartic acid is not an essential amino acid as it can be synthesized in the body from other substrates, however it still has many key functions such as for testosterone production.

This is why many supplement companies advertise d-aspartic acid as a “testosterone-booster”.

The Potential Benefits of D-Aspartic Acid

Below we've listed every potential benefit we've found with credible scientific backing:

It May Increase Hormone Levels

Studies on d-aspartic acid have demonstrated that it can increase the synthesis of testosterone by three main mechanisms:

  • Signaling for the transcription of a compound called StAR that can regulate androgen synthesis in leydig cells within the testes [1] [2].
  • Attaching to NMDA receptors in the testes, that have the ability to induce testosterone release via a synergist reaction with hCG [3].
  • Accumulating in the anterior pituitary gland in the brain, causing the secretion of gonadotropin releasing hormone, growth-hormone releasing hormone, and prolactin releasing factors) which subsequently release luteinizing hormone, growth hormone, and prolactin, respectively [4].

However, it is interesting to note that these changes only seem to occur in the short-term.

When d-aspartic acid is taken for prolonged periods there is not a sustained measurable increase in testosterone production, suggested to be due to an increase in the enzyme that degrades d-aspartic acid.

This would suggest a possible negative feedback loop to maintain a state of homeostasis. Current experts in the field theorize that this negative regulation occurs in those with healthy testosterone levels, but not in those with low testosterone.

Another interesting finding is that as a knock-on effect of increasing testosterone, it may also be involved with spermatogenesis (production of sperm) [5]. ~3 grams of d-aspartate per day for 3 months in men with abnormal semen profiles saw a 50-100% improvements in sperm motility and concentration and it was associated with higher fertility rates [6].

However, it is also important for people to understand that although d-aspartic acid may raise testosterone levels slightly under some circumstances, it can also upregulate the aromatase enzyme which increases the production of estrogen [7].

This is not necessarily a major problem, but some customer reviews have stated that they experienced symptoms of gynecomastia (development of male breast tissue) from d-aspartic acid supplementation.

It May Increase Brain Function

D-aspartic acid has multiple roles to play within brain metabolism, in particular how it can influence neurotransmitters - chemical messengers which transmit chemical signals throughout the body.

Specifically, d-aspartic acid can effectively act as an endogenous neurotransmitter, as well as stimulate neuronal transmission by acting on neurotransmitter receptors such as NMDA [8] [9].

For these reasons, when animals are supplemented with d-aspartic acid for just 2 weeks it is able to enhance their brain function and memory [10].

Preliminary evidence in human trials suggests that d-aspartic acid is a “cognitive enhancer”, and the enzyme that converts l-aspartate to d-aspartate, called aspartate racemase, is crucial for regulating neurogenesis in humans [11].

It May Improve Body Composition

Many athletes and fitness enthusiasts take d-aspartic acid to improve their appearance and physical performance. Unfortunately, no such evidence exists to support its use.

In healthy resistance trained adults, 4 weeks of supplementation with 3 grams of d-aspartic acid failed to significantly increase lean body mass or reduce fat mass [12].

Further, another 12 week trial on resistance-trained men also reported no change in muscle size or thickness with 6 grams per day of supplementation [13].

At this time it is not recommended to consume d-aspartic acid to improve body composition.

How To Take D-Aspartic Acid?

The standard dose for d-aspartic acid is between 2-3 grams per day, however no official effective dose has been stated.

Research is currently underway to assess whether d-aspartic acid should be cycled, as testosterone boosters taken for prolonged periods may interfere with natural hormone production.

If you want to supplement with d-aspartic acid, we recommend a standard dose for a maximum of 2 months, with a 1 month break before consuming it again.

D-Aspartic Acid Safety And Side Effects

Human studies at the recommended dose (~3 grams per day) do not highlight any negative health effects to be concerned with [14].

This is in accordance with animal studies, where 50mg per kg of bodyweight is said to be a healthy dose.

The only concerns with d-aspartic acid are at very high doses (>15 grams per day) as this is the point where markers of oxidative stress and cellular damage increase within the testes. At these high doses, testicular weight has shown to decrease by ~10% and oxidative markers increase by 25-75%.

Limited evidence also indicate that high doses may impair mitochondrial function and interfere with energy production [15].

Conclusion

D-aspartic acid is a non-essential amino acid that has metabolic roles in testosterone production.

Current evidence suggests that supplementing with d-aspartic acid can increase testosterone levels in men with clinically low testosterone, however not in healthy populations.

Preliminary studies do however show an interesting role for enhancing brain function and memory.

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