Pure NAC + Glycine Powder Bluebird Pharmacy Supplementation with a combination of glycine and N acetylcysteine (precursors to glutathione) improved glutathione levels, oxidative stress, mitochondrial function, muscle strength, exercise capacity, cognition in older individuals. The supplement NAC is a great supplement. It's awesome stuff to support healthy lungs. NAC is a known mucolytic. That is a fancy term meaning breaking up mucus. Now, research does show that NAC Supplementing Glycine and N Acetylcysteine (GlyNAC) in Older Adults Benefits both Health Span and Lifespan USC Longevity Institute