GlyNAC (Glycine + N-Acetylcysteine)

GlyNAC scores 6.5–7.0/10, Worth trying, and is arguably the best-evidenced way to raise glutathione, while still carrying an honest asterisk about replication. The practical verdict is to treat it as a low-cost, high-safety experiment that is most likely to pay off in older adults, people with type 2 diabetes, or anyone with measured glutathione depletion. The effect sizes in the human trials, a 64 percent drop in insulin resistance and large gains in strength and mitochondrial function, are far beyond what most supplements deliver, and the precursor approach cleanly beats swallowing glutathione directly. The reason it lands in worth-trying rather than strong-recommend is that nearly all of that data comes from one laboratory in groups of a dozen people, and the single larger independent trial missed its primary endpoint. The score tier is justified by excellent safety and large demonstrated effects pulling up against concentrated, not-yet-replicated evidence and washout-dependent durability pulling down.

✅ Best for: Older adults, especially those over 65, who are the studied population and the most likely to be glutathione-depleted; people with type 2 diabetes or insulin resistance who will track HbA1c or HOMA-IR, the metabolic markers with the strongest signal; anyone with documented high oxidative-stress burden, the subset that benefited even in the independent Lizzo 2022 trial; biohackers who want the precursor route to glutathione rather than the poorly-absorbed direct form; and budget-conscious experimenters who value a cheap, very safe protocol they can run on themselves with a marker in hand.

❌ Avoid if: You expect a dramatic acute effect, because GlyNAC works gradually over weeks to months; you want a one-and-done fix, since benefits fade within about 12 weeks of stopping; you are a healthy, young, well-nourished person with normal glutathione, where human data is thin and the upside is smaller; you have asthma with a history of NAC-triggered bronchospasm, in which case introduce NAC cautiously and with clinician input; or you would rather wait for larger independent trials to confirm the single-lab outcomes before committing.