D-Aspartic Acid
D-aspartic acid is the mirror-image form of the amino acid aspartic acid. It occurs naturally in nerve and hormone-producing tissue and is mostly studied for testosterone.
Also listed as D-AA, D-Aspartate, DAA
What it is studied for
The strongest rated effects first. Bars show the size of the effect, the letter grades the evidence, and each rating lists the studies behind it.
Why is this amino acid sold for hormones?
D-aspartic acid occurs naturally in the body, including nervous and reproductive tissues. Animal and cell experiments suggest involvement in hormone signaling and testosterone production. That biological role prompted human trials, but does not establish that swallowing extra amounts raises testosterone. 1
Why people take it
SuppCo community snapshot, 2026-09-28. Reasons for use are not evidence that it works.
Questions people ask
Is D-aspartic acid the same as L-aspartic acid?
They are differently arranged forms of the same amino acid. Findings about D-aspartic acid should not be transferred to L-aspartic acid supplements. 1
Was the longer training trial positive?
No additional strength or muscle-size benefit was found over placebo after 12 weeks. 2
Does better sperm motility prove better fertility?
The uncontrolled study cannot establish that D-aspartate caused improved fertility, even though semen measures improved. 3
Asparagine
Glutamic Acid