N Acetyl Cysteine (Glutathione Precursor) Glutathione (GSH) and NAD are both critical for cellular health, energy, and repair. Yet, they function very differently in the body. The question I'm often asked is, "Which one do I need NAC Vs NAD: Understanding Their Key Differences And Benefits NAD+ vs Glutathione which one do you need? The answer: both. NAD+ fuels your cellssupporting energy, metabolism, and healthy aging. Glutathione protects your cellsreducing oxidative stress and supporting detoxification. They work together