D-Aspartic Acid: Research · Nutrient Desk

Does it raise testosterone?

A systematic review found inconsistent human results. An early short study reported higher testosterone, but had important design and analysis weaknesses. Trials in resistance-trained men did not reproduce a consistent increase; one short trial found lower testosterone with 6 g daily. 1

Testosterone BalanceMixed

The evidence does not support a dependable testosterone-boosting effect in trained men. Early positive findings remain a research question for other populations, rather than proof that the same response can be expected. 1

Does it add to strength training?

In a 12-week randomized trial, 22 trained men were assigned to 6 g daily or placebo; 19 completed the study. Both groups trained four times weekly. Supplementation did not add gains in strength or muscle size and did not increase total or free testosterone. 2

Strength TrainingNot supported

For this training program and population, D-aspartic acid offered no additional strength benefit over placebo. 2

What about sperm quality?

A 2012 study followed 60 men with impaired semen parameters for 90 days of sodium D-aspartate. Sperm concentration and motility improved compared with their own starting measurements. There was no placebo group, so the study cannot isolate the supplement’s contribution. 3

Sperm MotilityToo little evidence

This is a preliminary fertility signal worth testing in controlled trials, not an established treatment effect. 3

Effects by health goal

Open an effect to see the studies behind its rating. Bars show the size of the effect; the letter grades the evidence.