Glycine and aging: Evidence and mechanisms.

From this article:

• The restriction of calories, branched-chain amino acids, and methionine have all been shown to extend lifespan in model organisms. Recently, glycine was found to boost longevity in genetically heterogenous mice. This simple amino acid similarly extends lifespan in rats and improves health in mammalian models of age-related disease. … Glycine is abundant in collagen, a building block for glutathione, a precursor to creatine, and an acceptor for the enzyme glycine N-methyltransferase (GNMT). ….
• Taken all together, existing evidence suggests that glycine prolongs life by mimicking methionine restriction and activating autophagy.

More recent post explaining the Anti-aging mechanism in depth

I’m taking 5 grams glycine daily, half in the morning with NAC, half an hour before bed.