Evidence Level
Strong
NAC is one of the most versatile and well-studied amino acid supplements. Its value derives primarily from being the most cost-effective oral glutathione precursor. Beyond liver and antioxidant support, an expanding body of literature supports NAC for psychiatric conditions (OCD, trichotillomania, addiction, bipolar depression), likely through glutamate modulation and oxidative stress reduction in the brain. Its mucolytic properties add respiratory health benefits. Despite low oral bioavailability (~6-10%), it effectively raises tissue glutathione levels.