D-Aspartic Acid

Last Updated: December 27 2022

D-aspartic acid is an amino acid synthesized in the body and obtained through protein-containing foods or a dietary supplement. It may play a role in reproductive function and fertility.

D-Aspartic Acid is most often used for

What is D-aspartic acid?

D-aspartic acid and L-aspartic acid are the two naturally occurring forms of the amino acid aspartic acid.[54] Both are synthesized in the human body, they are also obtained through the diet via any dietary protein source.[54][55] While L-aspartic acid is used as a protein building block, D-aspartic acid is not.[54] Instead, D-aspartic acid has direct effects on the central nervous system and endocrine tissues.[54][56][57] This is why D-aspartic acid is also sold as a dietary supplement.

What are D-aspartic acid’s main benefits?

Cell culture (in vitro) experiments and animal studies suggest D-aspartic acid may play a role in testosterone synthesis and male fertility.[57][56] While D-aspartic acid can increase plasma testosterone levels in male rodents, the evidence for this effect in humans is limited[58][33][57] and the effect of supplementation with D-aspartic acid on human fertility is unclear.[56][57]

Although there is little to no evidence that D-aspartic acid increases testosterone and growth hormone levels in humans, because these effects have been observed in rodents,[58][54] D-aspartic acid supplements are marketed to increase muscle mass and strength when combined with resistance training. However, the current evidence does not support such claims in humans.[59][33][60]

What are D-aspartic acid’s main drawbacks?

It’s important to note that rodent studies show that daily supplementation with D-aspartic acid does not cause toxicity.[61] Furthermore, human studies have not reported evidence of toxicity or serious side effects.[33][60][59] One resistance training study of 20 men with no health conditions did report irritability, nervousness, rapid heart rate, and headache in 2 participants receiving D-aspartic acid, but the same adverse effects were also reported by 1 participant in the placebo group.[59] In the absence of toxicity or serious side effects, the main drawback of supplementation with D-aspartic acid is the lack of evidence for a beneficial effect in humans.

How does D-aspartic acid work?

D-aspartic acid is present in neurons and synapses in the brain, has a similar structure to the neurotransmitter N-methyl-D-aspartate (NMDA), and can bind to NMDA receptors. Therefore, it acts as a neurotransmitter/neuromodulator.[54][56][62] For example, D-aspartic acid directly affects neuroendocrine function in the hypothalamus and pituitary gland in the brain, causing the secretion of several hormones, including gonadotropin-releasing hormone, prolactin, luteinizing hormone, and growth hormone.[54][56][62] Additionally, D-aspartic acid directly affects cells in the testes, causing testosterone secretion.[54][56][62] However, many of these actions have only been detected in cell culture (in vitro) and/or animal studies, so their biological relevance in humans is not completely understood.

What else is D-Aspartic Acid known as?
Note that D-Aspartic Acid is also known as:
  • D-AA
  • D-Aspartate
  • DAA
D-Aspartic Acid should not be confused with:
  • DL-Aspartate
  • Aspartate
Dosage information

The standard dose for D-aspartic acid is between 2,000 – 3,000mg.

D-AA is taken daily.

Different studies have used different supplementation protocols. One study used 3,000mg for 12 days, taken daily, followed by a week with no supplementation. A different study did not cycle D-AA, and used 2,000mg of continual daily supplementation with no harm. Further study is needed to determine whether D-AA should be cycled.

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