GlyNAC — glycine plus N-acetylcysteine — reversed multiple hallmarks of aging in humans in a landmark Baylor trial. Pure Encapsulations NAC + Glycine Powder is the most convenient way to implement the protocol without swallowing 20+ capsules a day.
In 2021, a clinical trial from Baylor College of Medicine published in *Nature Communications* changed how longevity researchers think about two cheap, widely available amino acids. The trial supplemented older adults (average age 70) with glycine plus N-acetylcysteine — GlyNAC — for 24 weeks and measured a remarkable list of outcomes.
Compared to placebo, GlyNAC corrected glutathione deficiency, reduced oxidative stress, improved mitochondrial function, enhanced physical strength and cognition, lowered inflammatory markers (including IL-6 and TNF-α), improved insulin resistance, and reversed multiple molecular hallmarks of aging. The effect sizes were large enough to prompt follow-up trials and intense interest from the longevity community.
The challenge: the clinical trial used high doses — 100 mg/kg/day of glycine and 100 mg/kg/day of NAC — translating to roughly 7–8 grams of each for a 75 kg adult per day. Taking that from capsules requires 30–40 large capsules daily. Pure Encapsulations NAC + Glycine Powder solves this problem: a single scoop in water or a smoothie delivers a meaningful dose of both compounds in a clean, hypoallergenic formulation.
Glutathione — the body's master antioxidant — requires three amino acid building blocks: cysteine, glutamate, and glycine. In older adults, glutathione levels fall by 50–60% compared to young adults, primarily because:
1. Cysteine availability is rate-limiting (NAC donates cysteine, bypassing this bottleneck)
2. Glycine availability is co-limiting in aging tissue — glycine is produced endogenously but production capacity declines with age, and dietary intake rarely compensates
Supplementing NAC alone partially restores glutathione but is limited by glycine availability. Supplementing glycine alone is limited by cysteine. The combination restores both limiting substrates simultaneously and produces glutathione repletion that neither compound achieves individually — hence the clinical effect of the combination rather than either component in isolation.
Beyond glutathione synthesis, glycine has independent longevity effects: it is the primary substrate for collagen synthesis, suppresses mTORC1 (complementing fasting and rapamycin protocols), and improves sleep quality through glycine receptor activity in the brainstem. A separate 2019 meta-analysis of glycine supplementation for sleep found consistent improvements in subjective sleep quality at 3–5 g/day.
For the full intervention evidence, see the GlyNAC / NAC intervention page.
Pure Encapsulations is a physician-grade supplement brand known for:
The NAC + Glycine Powder specifically provides approximately 1,800 mg of NAC and 1,800 mg of glycine per scoop in a peach-ginger flavored powder that dissolves readily in 8–12 oz of water. The flavor is mild and easy to drink — an important practical consideration when you are taking this daily.
For reference, the Baylor RCT dose was substantially higher (100 mg/kg/day of each). At 3,600 mg/day of each compound, Pure Encapsulations' 1,800 mg per scoop is sub-Baylor. Two scoops per day (3,600 mg each of NAC and glycine) would approach the effective trial dose without approaching any safety concerns.
Dose escalation (recommended):
Timing: Take in the morning with breakfast or post-workout. NAC can occasionally cause nausea on an empty stomach, particularly at higher doses — taking it with food eliminates this for most people.
Duration: The 24-week Baylor trial saw progressive improvements throughout. Plan for a minimum 12-week commitment; most mechanistic changes (glutathione levels, oxidative stress markers) peak around 16–20 weeks.
Monitoring: If you want objective data, you can test:
The Baylor trial enrolled adults 71–80 years old with age-related decline. The most dramatic effects appear in:
Younger adults (40–65) can still benefit but the effect sizes are likely smaller because baseline glutathione depletion is less severe.
Both glycine and NAC have excellent safety records across decades of clinical use:
The one practical concern: high-dose NAC can chelate copper. If you are taking GlyNAC long-term at 2+ scoops per day, consider monitoring copper and ceruloplasmin annually or supplementing with a small amount of copper (1–2 mg/day).
GlyNAC fits naturally into most longevity protocols:
With NMN/NAD+ precursors: Complementary — glutathione and NAD+ are the two major redox buffers declining with age. GlyNAC addresses the glutathione side; NMN addresses the NAD+ side. No known negative interaction.
With Zone 2 exercise: Exercise acutely depletes glutathione through oxidative stress. GlyNAC replenishes it — the combination is synergistic for long-term antioxidant capacity.
With caloric restriction / fasting: Glycine suppresses mTOR, complementing fasting's mTOR inhibition. NAC supports liver detoxification pathways stressed during extended fasting. The combination is well-supported theoretically.
With rapamycin: Rapamycin inhibits mTOR; glycine modestly suppresses mTOR. No evidence of problematic interaction; theoretically additive for mTOR inhibition.
Why powder instead of capsules? At the Baylor trial dose (100 mg/kg/day of each), you would need roughly 16–20 NAC capsules and 10–12 glycine capsules daily. Powder is the only practical format for high-dose GlyNAC.
Can I mix this with creatine? Yes. The peach-ginger flavor mixes well with unflavored creatine monohydrate. Adding creatine further supports the muscle and cognitive benefits of the protocol.
Does NAC cause cancer concern? Early pre-clinical studies raised questions about NAC's role in certain cancer contexts (a 2019 *Nature Medicine* study showed NAC promoted metastasis in mouse melanoma). This remains unresolved in humans, and the clinical evidence base for NAC in humans does not show increased cancer risk. Adults with active cancer should discuss NAC supplementation with their oncologist before starting.
How does this compare to liposomal glutathione? Liposomal glutathione supplements glutathione directly but bypasses the natural regulation of intracellular glutathione synthesis. GlyNAC restores the body's endogenous production machinery, which many researchers consider more physiologically appropriate.