Is taking GlyNAC better than taking NAC alone?

Theoretically, yes. Certain groups of people (such as older adults) can have both reduced glutathione levels and reduced cysteine and glycine levels.^[1] Although both glycine and cysteine can be produced by the body, their levels seem to be highly influenced by diet, and it’s possible that endogenous production of these amino acids may not be sufficient in people with higher demand (such as people with high levels of oxidative stress).^[2][3]