Nelson Vergel
Founder, ExcelMale.com
In a recently published placebo controlled study, D-ASP supplementation was found to be ineffective in up-regulating the activity of the hypothalamo-pituitary-gonadal axis and to have no anabolic or ergogenic effects in skeletal muscle.
http://www.nrjournal.com/article/S0271-5317(13)00173-5/abstract
However, d-Aspartic Acid was shown to work in a previous study (not placebo controlled) in Italy: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2774316/
Almost every supplement out there has contradictory data. This one is no different. It is very difficult to trust data when several studies show different and contradictory results. However, most research labs studying supplements do not have the large budgets that pharma has, so studies tend to be smaller and not as well controlled. Very few supplement studies are funded by the National Institute of Health in the US.
Since the FDA does not regulate supplements, most companies can make any claim as long as they say (usually in tiny words on the label): "This statement has not been reviewed by the FDA".