GlyNAC for Health & Longevity - Quick Reference Sheet
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GlyNAC for Health & Longevity

Created on 09/13/2026 – Quick Reference based on Evidence Review created using AI4L / Opus 5 – Audit

Two inexpensive amino acids rebuild the body's main internal antioxidant, which falls with age. Walking speed and grip strength improved in older adults, holding only while use continues. Metabolic measures and blood pressure moved in one small controlled trial. Longer life shown only in mice. Gastrointestinal upset, evening drowsiness, and possible blunting of training adaptation are the trade-offs. (Full Review)

Protocol

Standard regimen
Roughly 7 g glycine + 9 g N-acetylcysteine daily (70 kg adult)
Glycine 1.33 mmol/kg and cysteine 0.81 mmol/kg daily, given as N-acetylcysteine
Split versus single dose
Two divided doses
Roughly 6-hour half-life and the powder volume argue against a single sitting
Best time of day
Morning and evening with meals
Food blunts nausea; the evening dose puts glycine's sleep-promoting effect to use
Time to effect
Physical function
12–24 weeks
Cognition and body composition needed the same 12–24 weeks in the trials
Systolic blood pressure
16 weeks
Moved toward the young-adult range in the placebo-controlled trial
Glutathione and oxidative-damage markers
Within 2 weeks
Benefits are maintenance-dependent and fade after withdrawal

Benefits

Contraindications
  • Active or progressing malignancy, or cancer treated within the past five years
  • Chronic kidney disease stage 4 or 5 (filtration below 30 mL/min/1.73 m², or creatinine above 1.5 mg/dL)
  • Liver disease: transaminases above twice normal, or cirrhosis Child-Pugh B or C
  • Poorly controlled asthma (forced expiratory volume in one second below 60% of predicted), or documented acetylcysteine-induced bronchospasm
  • Known hypersensitivity to acetylcysteine in any form
  • Pregnancy and breastfeeding
  • Concurrent clozapine
  • Adults under 40
    •
Key Interactions
  • Organic nitrates for angina (nitroglycerin, isosorbide dinitrate)
  • Blood-pressure medicines (lisinopril, losartan, amlodipine)
  • Carbamazepine
  • Anticoagulants and antiplatelets (warfarin, apixaban, aspirin)
  • Antipsychotics other than clozapine (risperidone, haloperidol)
  • Activated charcoal
  • Acetaminophen, also sold as paracetamol
  • Other antioxidant supplements (vitamin C, vitamin E, alpha-lipoic acid)
  • Blood-pressure-lowering supplements (beetroot, magnesium, omega-3)
  • Sedating supplements (melatonin, magnesium glycinate, valerian)
  • Trace-mineral supplements (zinc, copper, selenium)
  • Hormetic interventions (sauna, cold exposure, hyperbaric oxygen)
    •

Risk & Side Effects

  • High: Gastrointestinal intolerance from N-acetylcysteine
    •
  • Medium: Blunted muscle recovery and training adaptation
    •
  • Low: Anaphylactoid reactions to N-acetylcysteine; daytime drowsiness and lowered core body temperature from glycine; amino-acid and nitrogen load in impaired kidney or liver function
  • Speculative: Acceleration of existing tumour growth; long-term suppression of beneficial oxidative signalling

Monitoring

Marker Target Why
Serum creatinine and estimated glomerular filtration rate Creatinine 0.6–1.1 mg/dL; filtration rate above 80 mL/min/1.73 m² Kidney handling of a large nitrogen and sulfate load
Alanine aminotransferase and aspartate aminotransferase Both below 25 U/L Liver tolerance of sustained thiol loading
Fasting insulin 2–5 µIU/mL The metabolic endpoint that moved most
Fasting glucose 75–90 mg/dL Tracks the fat-versus-glucose burning shift
Glycated haemoglobin 4.8–5.3% Slow-moving confirmation that fasting changes are real
High-sensitivity C-reactive protein Below 0.8 mg/L The most contested claim; the validated way to test it personally
Homocysteine 6–8 µmol/L N-acetylcysteine lowers it; glycine loads the same methyl-group pathway
Seated systolic blood pressure 105–120 mmHg The one validated clinical surrogate the placebo-controlled trial moved
Whole-blood reduced glutathione, with the reduced-to-oxidised ratio No established target; track change from personal baseline The mechanism's proximate output; an independent trial failed to move it
4-metre gait speed Above 1.0 m/s, and rising from personal baseline Function, not biochemistry, is what the strongest evidence supports
Handgrip strength Above 27 kg (men) or 16 kg (women), and rising from personal baseline Cheap, reproducible proxy for the strength endpoint the trials used

Cadence: Creatinine and transaminases at baseline, 4 and 12 weeks, then every 3–6 months; metabolic and inflammatory markers, blood pressure and the two function measures at baseline, 12 and 24 weeks, then every 6–12 months

Qualitative Assessment

  • Sleep onset latency and subjective sleep depth, which glycine plausibly changes within days
  • Daytime energy and the sense of effort during routine stair climbing or walking
  • Cognitive clarity, word-finding and mental stamina in the late afternoon
  • Recovery soreness after resistance training, where blunting is the signal of interest
  • Gastrointestinal comfort, bloating and stool consistency during dose escalation
Not medical advice. Educational distillation of a single evidence review. Confirm any decision with a qualified clinician, especially in the presence of prescription drugs or chronic conditions.