What are D-aspartic acid’s main drawbacks?

It’s important to note that rodent studies show that daily supplementation with D-aspartic acid does not cause toxicity.^[1] Furthermore, human studies have not reported evidence of toxicity or serious side effects.^[2][3][4] One resistance training study of 20 men with no health conditions did report irritability, nervousness, rapid heart rate, and headache in 2 participants receiving D-aspartic acid, but the same adverse effects were also reported by 1 participant in the placebo group.^[4] In the absence of toxicity or serious side effects, the main drawback of supplementation with D-aspartic acid is the lack of evidence for a beneficial effect in humans.