Evidence comparison

NAC (N-Acetylcysteine) vs Glycine

How they actually compare on the evidence — trial volume, literature, mechanism, and our honest confidence grade. Higher counts reflect research attention, not proof of superiority.

Western · Antioxidant

NAC (N-Acetylcysteine)

80Confidence

Extensive human-trial evidence

RCTs: 933
Meta: 377
Trials: 1

Key active: N-acetylcysteine — glutathione precursor

Medical-grade compound; GlyNAC RCT in older adults; aging-specific trials ongoing

NAC replenishes cysteine, the rate-limiting substrate for glutathione synthesis. Glutathione declines ~50% by age 65. The GlyNAC protocol (glycine + NAC, 2021 Baylor RCT) corrected glutathione deficiency alongside mitochondrial dysfunction, insulin resistance, and oxidative stress in older adults. NAC is FDA-approved for acetaminophen overdose and mucolytic use.

Full NAC (N-Acetylcysteine) evidence →

Western · Amino Acid

Glycine

74Confidence

Extensive human-trial evidence

RCTs: 1,722
Meta: 399
Trials: 4

Key active: Glycine (conditionally essential amino acid)

Strong NIH preclinical lifespan data; GlyNAC human RCT; direct aging trials limited

Glycine is rate-limiting for glutathione synthesis alongside cysteine, and is required for collagen and creatine biosynthesis. It also suppresses mTORC1 via its sensor GCN2. Glycine supplementation extended median lifespan in mice by 28–31% (NIH ITP). The GlyNAC combination (2021 Baylor RCT) corrected multiple aging hallmarks in older adults.

Full Glycine evidence →

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Commission research

Informational only — not medical advice or a recommendation to take either. Trial and literature counts are registry/database matches and include endpoints beyond longevity. See each ingredient page for sources.