D-Aspartic Acid

Last Updated: July 22, 2023

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.[1] Both are synthesized in the human body, they are also obtained through the diet via any dietary protein source.[1][2] While L-aspartic acid is used as a protein building block, D-aspartic acid is not.[1] Instead, D-aspartic acid has direct effects on the central nervous system and endocrine tissues.[1][3][4] 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.[4][3] While D-aspartic acid can increase plasma testosterone levels in male rodents, the evidence for this effect in humans is limited[5][6][4] and the effect of supplementation with D-aspartic acid on human fertility is unclear.[3][4]

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,[5] [1] 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.[7][6][8] In fact, the small number of human trials that do exist have actually found small reductions in testosterone.

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.[9] Furthermore, human studies have not reported evidence of toxicity or serious side effects.[6][8][7] 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.[7] 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.[1][3][10] 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.[1][3][10] Additionally, D-aspartic acid directly affects cells in the testes, causing testosterone secretion.[1][3][10] 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 are other names for D-Aspartic Acid?
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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  1. ^D'Aniello AD-Aspartic acid: an endogenous amino acid with an important neuroendocrine roleBrain Res Rev.(2007 Feb)
  2. ^Ohide H, Miyoshi Y, Maruyama R, Hamase K, Konno RD-Amino acid metabolism in mammals: biosynthesis, degradation and analytical aspects of the metabolic study.J Chromatogr B Analyt Technol Biomed Life Sci.(2011-Nov-01)
  3. ^Usiello A, Di Fiore MM, De Rosa A, Falvo S, Errico F, Santillo A, Nuzzo T, Chieffi Baccari GNew Evidence on the Role of D-Aspartate Metabolism in Regulating Brain and Endocrine System Physiology: From Preclinical Observations to Clinical Applications.Int J Mol Sci.(2020-Nov-18)
  4. ^Di Fiore MM, Boni R, Santillo A, Falvo S, Gallo A, Esposito S, Baccari GCD-Aspartic Acid in Vertebrate Reproduction: Animal Models and Experimental Designs.Biomolecules.(2019-Sep-03)
  5. ^Roshanzamir F, Safavi SMThe putative effects of D-Aspartic acid on blood testosterone levels: A systematic review.Int J Reprod Biomed.(2017-Jan)
  6. ^Melville GW, Siegler JC, Marshall PWMThe effects of d-aspartic acid supplementation in resistance-trained men over a three month training period: A randomised controlled trialPLoS One.(2017 Aug 25)
  7. ^Willoughby DS, Leutholtz BD-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 menNutr Res.(2013 Oct)
  8. ^Melville GW, Siegler JC, Marshall PWThree and six grams supplementation of d-aspartic acid in resistance trained menJ Int Soc Sports Nutr.(2015 Apr 1)
  9. ^Schieber A, Brückner H, Rupp-Classen M, Specht W, Nowitzki-Grimm S, Classen HGEvaluation of D-amino acid levels in rat by gas chromatography-selected ion monitoring mass spectrometry: no evidence for subacute toxicity of orally fed D-proline and D-aspartic acid.J Chromatogr B Biomed Sci Appl.(1997-Mar-28)
  10. ^Ota N, Shi T, Sweedler JVD-Aspartate acts as a signaling molecule in nervous and neuroendocrine systems.Amino Acids.(2012-Nov)
  11. ^Ebben M, Lequerica A, Spielman AEffects of pyridoxine on dreaming: a preliminary studyPercept Mot Skills.(2002 Feb)
  12. ^De Souza MC, Walker AF, Robinson PA, Bolland KA synergistic effect of a daily supplement for 1 month of 200 mg magnesium plus 50 mg vitamin B6 for the relief of anxiety-related premenstrual symptoms: a randomized, double-blind, crossover studyJ Womens Health Gend Based Med.(2000 Mar)
Examine Database References
  1. Lean Mass - Darryn S. Willoughby, Brian Leutholtzd-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 menNutrition Research.()
  2. Testosterone - Melville GW, Siegler JC, Marshall PWThree and six grams supplementation of d-aspartic acid in resistance trained menJ Int Soc Sports Nutr.(2015 Apr 1)
  3. Testosterone - mma D’Aniello, Salvatore Ronsini, Tiziana Notari, Natascia Grieco, Vincenzo Infante, Nicola D’Angel, Fara Mascia, Maria Maddalena Di Fiore, George Fisher, Antimo D’AnielloD-Aspartate, a Key Element for the Improvement of Sperm QualityMedicine and Healthcare.()
  4. Testosterone - Topo E, Soricelli A, D'Aniello A, Ronsini S, D'Aniello GThe role and molecular mechanism of D-aspartic acid in the release and synthesis of LH and testosterone in humans and ratsReprod Biol Endocrinol.(2009 Oct 27)