Found a study which seems to argue that D-serine and/or Glycine are competitive agonists with regards to another compound at the glycine binding site.
What other compound you ask? Believe it or not: Piracetam.A potentiation of response to glutamate and aspartate through the glycine site of the NMDA receptor by piracetam has been reported in a Russian study. Another study showed that piracetam and aniracetam at 100 PM do not affect MK-801 binding in the presence of NMDA and glycine. If piracetam acts on the glycine regulatory site of the NMDA receptor the presence of glycine could obscure the potentiating effect of piracetam.
In theory this doesn't make any sense. Glycine and/or D-serine are necessary co-agonists at the NMDA receptor site.
so does that mean it is beneficial or negative?
they say it would obscure the effect of piracetam.