Last verified: 17 days ago
Aspartic Acid
Also known as: L-aspartic acid, D-aspartic acid, D-Asp, aspartate, aminosuccinic acid
Evidence under review. — Not yet rated
Amino acid found in food and the body. Limited evidence supports modest testosterone and sperm benefits in infertile men.
-
What it does
Aspartic acid is a non-essential amino acid naturally produced by the body and found in protein-rich foods. The D-form (D-aspartic acid) has been studied in men with idiopathic infertility, where...
-
Evidence quality
Evidence base hasn't been formally rated yet. See research below.
-
Clinical dose
No established dose
-
Found in
Naked Nutrition Grass Fed Whey Protein Powder, TestoPrime, Fairwaymarket and 5 more
What the Science Says
Aspartic acid is a non-essential amino acid naturally produced by the body and found in protein-rich foods. The D-form (D-aspartic acid) has been studied in men with idiopathic infertility, where one clinical trial found that 2660 mg daily (combined with ubiquinol and zinc) improved progressive sperm motility and raised total testosterone levels over 3 months. It also appears as a metabolic biomarker in conditions like hypertension, and its metabolite N-acetyl-aspartic acid is relevant to rare neurological diseases, though these are observational findings rather than evidence of supplementation benefit.
What It Doesn't Do
Not proven to boost testosterone in healthy men with normal levels. No evidence it builds muscle or improves athletic performance on its own. The infertility study combined it with zinc and CoQ10, so aspartic acid alone gets no solo credit. Don't expect it to fix fertility problems without medical evaluation.
Evidence-Based Benefits
May improve sperm motility and testosterone in infertile men when combined with zinc and CoQ10.
Weak EvidenceEffective at: 2660 mg/day (combined formula)
Supporting studies (click to view on PubMed):
Aspartic acid-rich soy hydrolysate peptides may enhance iron absorption in adolescent girls with low iron stores.
Weak EvidenceEffective at: No established dose
Supporting studies (click to view on PubMed):
Absorption & Bioavailability
Unknown — no pharmacokinetic data provided in the available studies. As a free amino acid it is generally expected to be absorbed, but absorption data specific to supplemental aspartic acid was not reported in the provided papers.
Red Flags to Watch For
- The only clinical trial on D-aspartic acid for infertility combined it with zinc and ubiquinol — impossible to isolate aspartic acid's individual contribution
- No dose-ranging studies provided; the 2660 mg dose used in the trial is not validated as optimal or safe long-term
- Aspartame (an artificial sweetener) metabolizes into aspartic acid; long-term high-dose aspartame consumption has been linked to epigenetic changes in rat studies — relevance to supplemental aspartic acid is unclear
- Many products in the NIH DSLD database contain aspartic acid, but widespread commercial use does not equal proven efficacy
Products Containing Aspartic Acid
See how Aspartic Acid is used in these analyzed products:
Naked Nutrition Grass Fed Whey Protein Powder
Supplement
TestoPrime
Supplement
Fairwaymarket
Supplement
Elm & Rye Vegan Protein Blend
Supplement
Nitric Boost Ultra
Supplement
Optimum Nutrition 100% Gold Standard Whey
Supplement
Naked Goat Whey Protein Powder
Supplement
Everyday Dose
Supplement
Frequently Asked Questions
What does Aspartic Acid do?
Amino acid found in food and the body. Limited evidence supports modest testosterone and sperm benefits in infertile men.
What is the effective dose of Aspartic Acid?
No established dose
Is Aspartic Acid safe?
The only clinical trial on D-aspartic acid for infertility combined it with zinc and ubiquinol — impossible to isolate aspartic acid's individual contribution
What doesn't Aspartic Acid do?
Not proven to boost testosterone in healthy men with normal levels.
Research Sources
- PubMed
- NIH DSLD
This information is for educational purposes only and is not medical advice. Always consult a healthcare professional before starting any supplement regimen. Last updated: 2026-05-25