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Ingredients

D-Aspartic Acid

D-Aspartic acid supplementation

Snapshot

IndicationsContraindications
  • Blood testosterone levels in men1
  • Resistance training outcomes2–5
  • Semen parameters6
  • Pregnancy or nursing7
  • Under 18 years7

D-aspartic acid is the D-form of aspartic acid, an endogenous amino acid found in neuroendocrine tissue that participates in hormone release along the hypothalamic-pituitary-gonadal axis8. It is taken as a testosterone booster, mainly by male athletes and lifters seeking muscle and strength gains, and by men with fertility concerns.

Human research is limited to about six small trials, mostly in resistance-trained men with hormone outcomes, plus one in male infertility. A systematic review found exogenous D-aspartic acid raised testosterone in male animals, while human results were inconsistent and the studies few and of poor quality1. A 2025 randomized placebo-controlled trial tested D-aspartic acid combined with ubiquinol and zinc on semen parameters in idiopathic male infertility. Products are sold as powders and capsules, with many thousands of products listing D-aspartic acid; see Form comparison.

Cautions come mainly from labeling. Health Canada lists a practitioner consultation before use in pregnancy or breastfeeding9, and some United States labels advise against use in pregnancy, nursing, or under age 187.

Last updated October 17, 2026. Read how we make monographs.

In the full monograph

28 sources, 17 studies

  • When to useThe situations practitioners use it for, each with the reason and the study behind it.
  • SafetyWho should avoid it, who needs extra care, and the side effects reported in studies.
  • InteractionsThe medicines and supplements it interacts with, the effect of each, and what labeling says to watch.
  • Protocol notesThe doses used in studies, how and when they were taken, and how the forms on the market compare.
  • How it worksWhat it is and how it works in the body, in plain terms.
  • Published studiesThe studies behind each use, popular claims checked against them, and trials still under way.
  • Word of mouthWhat patients and practitioners report online, kept separate from the clinical evidence.
  • Clinical perspectiveA closing read of where the evidence is solid, where it is thin, and what has not been studied.
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Sources

  1. 1The putative effects of D-Aspartic acid on blood testosterone levels: A systematic review.pubmed.ncbi.nlm.nih.govRoshanzamir, Safavi · International journal of reproductive biomedicine · 2017 · Pubmed
  2. 2D-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.pubmed.ncbi.nlm.nih.govWilloughby, Leutholtz · Nutrition research (New York, N.Y.) · 2013 · Pubmed
  3. 3The effects of d-aspartic acid supplementation in resistance-trained men over a three month training period: A randomised controlled trial.pubmed.ncbi.nlm.nih.govMelville, Siegler, Marshall · PloS one · 2017 · Pubmed
  4. 4Short-Term d-Aspartic Acid Supplementation Does Not Affect Serum Biomarkers Associated With the Hypothalamic-Pituitary-Gonadal Axis in Male Climbers.pubmed.ncbi.nlm.nih.govCrewther, Witek, Draga et al. · International journal of sport nutrition and exercise metabolism · 2019 · Pubmed
  5. 5The Effects of Six-Gram D-Aspartic Acid Supplementation on the Testosterone, Cortisol, and Hematological Responses of Male Boxers Subjected to 11 Days of Nocturnal Exposure to Normobaric Hypoxia.pubmed.ncbi.nlm.nih.govPłoszczyca, Czuba, Zakrzeska et al. · Nutrients · 2023 · Pubmed
  6. 6Evaluation of in vivo supplementation of 2660 mg D-aspartic acid and 200 mg ubiquinol and 10 mg zinc on different semen parameters in idiopathic male infertility: a randomized double blind placebo controlled study.pubmed.ncbi.nlm.nih.govGamalEl Din, A M, Elkhiat et al. · Archivio italiano di urologia, andrologia : organo ufficiale [di] Societa italiana di ecografia urologica e nefrologica · 2025 · Pubmed
  7. 7US product labelsdsld.od.nih.govWarnings printed on US dietary supplement labels with this ingredient, from the NIH Office of Dietary Supplements' Dietary Supplement Label Database (DSLD). Manufacturers' precautions, not evidence of harm
  8. 8D-Aspartic acid: an endogenous amino acid with an important neuroendocrine role.pubmed.ncbi.nlm.nih.govD'Aniello · Brain research reviews · 2007 · Pubmed
  9. 9Health Canadahealth-products.canada.caLabel statements and adult daily amounts Health Canada authorized on licensed natural health products with this ingredient alone, from the Licensed Natural Health Products Database. Contains information licensed under the Open Government Licence – Canada