OtherSupplementAmino acid

D-Aspartic Acid (DAA)

Also known as DAA · D-aspartate · Sodium D-aspartate

Written by enwyReviewed 5 Aug 20262 sources0 comments

D-aspartic acid is an amino acid that acts as a signalling molecule in the hypothalamus and testes, and it became a popular testosterone booster after an early positive human study. Follow-up trials, especially in resistance-trained men, largely failed to replicate a testosterone increase, and some found free testosterone actually fell at higher doses. The overall evidence is now mixed-to-negative.

01 Overview

D-aspartic acid stimulates release of LH and GnRH and is involved in testicular testosterone synthesis, which gave a plausible mechanism for the initial 2009 finding of raised testosterone in untrained men. However, a subsequent well-controlled trial in trained men found no benefit at 3 g/day and a decrease in testosterone at 6 g/day, undermining the earlier result.

Users take it as a cheap standalone booster or in stacks, though enthusiasm has faded as replication failed. It is generally well tolerated, with occasional irritability, headache or GI upset. Any benefit, if present, appears limited to untrained or low-testosterone individuals and is not reliable.

02 Mechanism

Amino acid that acts as a signalling molecule promoting hypothalamic GnRH and pituitary LH release and participates in testicular testosterone synthesis; net human effect is inconsistent.

03 Dosing

Tier	Dose	Route	Notes
Standard dose	2000–3000 mg/day	Oral	The 3 g/day dose used in the original positive study.
High dose (not advised)	3000–6000 mg/day	Oral	6 g/day was associated with reduced testosterone in trained men.

04 Effects

Effect	Magnitude	Evidence
Transient testosterone rise in untrained menAn early study reported a ~30-40% short-term rise in untrained men, but this has not reliably replicated.	small / unreliable	Disputed
No benefit (or decline) in trained menControlled trials in resistance-trained men show no increase, with a fall in testosterone at 6 g/day.	none to negative	Clinical

05 Side effects

Effect	Severity	Frequency	Evidence	Countermeasures
Irritability / mood changesSome users report irritability, anxiety or headaches.	Mild	Uncommon	Anecdotal
Possible testosterone suppression at high doseAt 6 g/day, one trial found reduced free and total testosterone.	Moderate	High-dose	Clinical

06 Legal status

United States

Dietary supplement

as of Jan 2026

United Kingdom

Food supplement

as of Jan 2026

07 References

The role and molecular mechanism of D-aspartic acid in the release and synthesis of LH and testosteroneReprod Biol Endocrinol, 2009

Three and six grams supplementation of D-aspartic acid in resistance trained menJ Int Soc Sports Nutr, 2015

08 Discussion0 comments

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This page is reference information, not medical advice. Doses and protocols are documented as they appear in the clinical literature and in practice — describing them is not a recommendation to use them. Countermeasures listed here are not a substitute for a physician. Legal status varies by jurisdiction and changes.