Glycine + NAC (GlyNAC)

Overview

GlyNAC is the combined oral supplementation of the two rate-limiting amino acid precursors of glutathione (GSH): glycine and N-acetylcysteine (a stable, absorbable form of cysteine). Glutathione is the body's principal intracellular antioxidant, and its concentration declines markedly with age — a deficit that GlyNAC has been shown in human trials to correct.

Natural sources

Synthesized from dietary glycine (gelatin, bone broth, collagen) and cysteine (whey, eggs, poultry)
Sold as a combined GlyNAC supplement or as separate glycine + NAC powders/capsules

Common forms

Combined GlyNAC capsules
Glycine powder + NAC capsules taken together
Free-form L-glycine + N-acetyl-L-cysteine

Mechanism of action

Provides both rate-limiting substrates for de novo glutathione synthesis. NAC delivers cysteine for the γ-glutamylcysteine synthetase step; glycine completes the tripeptide via glutathione synthetase. Restoring GSH lowers oxidative stress, improves mitochondrial fatty-acid oxidation, normalizes insulin signaling, and reduces inflammatory cytokines (IL-6, TNF-α).

Pathways

· Glutathione (GSH) de novo synthesis
· Mitochondrial fatty-acid β-oxidation
· Redox / Nrf2 antioxidant response
· Insulin signaling and glucose disposal
· Cellular senescence and genomic damage markers

Enzymes

· γ-Glutamylcysteine synthetase (GCL)
· Glutathione synthetase
· Glutathione peroxidase

Effects on the body

Increases

Red blood cell and intracellular glutathione

Decreases

Oxidative stress markers (8-OHdG, F2-isoprostanes, MDA)

Supports

Mitochondrial fatty-acid oxidation and ATP output

Decreases

Inflammatory cytokines (IL-6, TNF-α, hsCRP)

Supports

Insulin sensitivity and fasting glucose

Decreases

Genomic damage and senescence markers

Organ system effects

Liver

Restores hepatic glutathione; supports phase-II detoxification and protects against oxidative liver injury.

Skeletal Muscle

Improves mitochondrial function, grip strength, and gait speed in older adults.

Brain & CNS

Lowers oxidative stress and neuroinflammation; preliminary data in Alzheimer's pilots show cognitive benefit.

Cardiovascular

Improves endothelial function and lowers systolic blood pressure in older adults.

Evidence-based benefits

Restores glutathione to youthful levels in older adults

Moderate evidence

Improves mitochondrial function and physical performance (grip strength, gait speed)

Moderate evidence

Lowers oxidative stress, inflammation, and insulin resistance markers

Moderate evidence

Improves cognition in pilot Alzheimer's disease trials

Limited evidence

Improves metabolic parameters and inflammation in HIV patients

Moderate evidence

Potential side effects

Common

· Mild GI upset (bloating, loose stools)
· Sulfur-like odor from NAC
· Transient headache at higher doses

Rare

· Skin rash
· Nausea

Serious

· Rare bronchospasm with NAC in asthmatics (more relevant to inhaled NAC)

Drug interactions

Nitroglycerin / nitrates

NAC potentiates vasodilation and may cause hypotension/headache.

moderate

Activated charcoal

Reduces NAC absorption — separate by ≥2 h.

moderate

Antihypertensives

Additive lowering of blood pressure possible.

minor

Supplement interactions

Pairs well with

Magnesium glycinate
Additional glycine delivery and improved sleep quality during the protocol.
B-complex (B6, B12, folate)
Supports methionine/transsulfuration cycle that feeds cysteine availability.
CoQ10 or PQQ
Complementary mitochondrial support alongside GSH restoration.

Avoid combining with

Cisplatin and certain chemotherapy
Antioxidants may blunt cytotoxic efficacy — coordinate with oncologist.

Dosing & bioavailability

Typical dose

Glycine 100 mg/kg/day + NAC 100 mg/kg/day, split into two daily doses with meals (≈7 g of each for a 70 kg adult)

Study range

Baylor trials used 100 mg/kg/day of each for 16–24 weeks; pilot AD trial used the same dose for 24 weeks

Upper safe limit

Not formally established; doses up to 100 mg/kg of each were well tolerated in trials up to 24 weeks

Best form

Pharmaceutical-grade L-glycine powder + N-acetyl-L-cysteine capsules or a combined GlyNAC product

Timing

Split AM and PM with food to minimize GI effects

With food?

With meals (improves tolerance)

Where to buy

Affiliate links — we may earn a commission at no extra cost to you. Amazon code supplementsch-20 is auto-applied at checkout. We don't endorse specific brands; verify third-party testing (USP, NSF, Informed Sport) before purchase.

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GlyNAC supplementation in older adults — 16-week RCT

Kumar P, Liu C, Hsu JW, Chacko S, Minard C, Jahoor F, Sekhar RV

24 older adults vs 12 younger controls receiving 100 mg/kg/day each of glycine and NAC for 16 weeks.

Key findings

Corrected glutathione deficiency, lowered oxidative stress and inflammation, improved mitochondrial function, insulin resistance, endothelial function, gait speed, strength, and cognition.

Open study

RCTNutrients · 2022

GlyNAC improves multiple defects in aging — 24-week RCT

Kumar P, Osahon OW, Sekhar RV

24-week follow-up extending the 16-week protocol in older adults.

Key findings

Sustained gains in GSH, mitochondrial fuel oxidation, insulin sensitivity, cognition, gait speed, and reductions in inflammation and genomic damage.

Open study

CohortAntioxidants (Basel) · 2023

GlyNAC in Alzheimer's disease — open-label pilot

Sekhar RV, et al.

Open-label pilot in early-stage AD patients receiving GlyNAC for 24 weeks.

Key findings

Improvements in cognition, gait speed, oxidative stress and inflammation markers; supports a larger RCT.

Open study

RCTAm J Physiol Endocrinol Metab · 2014

GlyNAC corrects glutathione deficiency in HIV

Nguyen D, Hsu JW, Jahoor F, Sekhar RV

Adults with HIV given glycine + cysteine precursors.

Key findings

Restored GSH, improved insulin sensitivity, mitochondrial fuel oxidation, and lowered oxidative stress.

Open study

Systematic reviewPubMed (NLM) · 1970

PubMed: Glycine + NAC (GlyNAC) — Restores glutathione to youthful levels in older adults

Live PubMed search

Live results for "Glycine + NAC (GlyNAC) Restores glutathione to youthful levels in older adults" across the PubMed/MEDLINE peer-reviewed index.

Key findings

Opens current human and preclinical literature matching Glycine + NAC (GlyNAC) and "Restores glutathione to youthful levels in older adults". Filter by RCT, meta-analysis, or year on the results page.

Open study

Systematic reviewPubMed (NLM) · 1970

PubMed: Glycine + NAC (GlyNAC) — Improves mitochondrial function and physical performance

Live PubMed search

Live results for "Glycine + NAC (GlyNAC) Improves mitochondrial function and physical performance" across the PubMed/MEDLINE peer-reviewed index.

Key findings

Opens current human and preclinical literature matching Glycine + NAC (GlyNAC) and "Improves mitochondrial function and physical performance". Filter by RCT, meta-analysis, or year on the results page.

Open study

Systematic reviewPubMed (NLM) · 1970

PubMed: Glycine + NAC (GlyNAC) — Lowers oxidative stress, inflammation, and insulin resistance markers

Live PubMed search

Live results for "Glycine + NAC (GlyNAC) Lowers oxidative stress, inflammation, and insulin resistance markers" across the PubMed/MEDLINE peer-reviewed index.

Key findings

Opens current human and preclinical literature matching Glycine + NAC (GlyNAC) and "Lowers oxidative stress, inflammation, and insulin resistance markers". Filter by RCT, meta-analysis, or year on the results page.

Open study

Systematic reviewPubMed (NLM) · 1970

PubMed: Glycine + NAC (GlyNAC) — Improves cognition in pilot Alzheimer's disease trials

Live PubMed search

Live results for "Glycine + NAC (GlyNAC) Improves cognition in pilot Alzheimer's disease trials" across the PubMed/MEDLINE peer-reviewed index.

Key findings

Opens current human and preclinical literature matching Glycine + NAC (GlyNAC) and "Improves cognition in pilot Alzheimer's disease trials". Filter by RCT, meta-analysis, or year on the results page.

Open study

Systematic reviewPubMed (NLM) · 1970

PubMed: Glycine + NAC (GlyNAC) — randomized controlled trial

Live PubMed search

Live results for "Glycine + NAC (GlyNAC) randomized controlled trial" across the PubMed/MEDLINE peer-reviewed index.

Key findings

Opens current human and preclinical literature matching Glycine + NAC (GlyNAC) and "randomized controlled trial". Filter by RCT, meta-analysis, or year on the results page.

Open study

Systematic reviewPubMed (NLM) · 1970

PubMed: Glycine + NAC (GlyNAC) — meta-analysis

Live PubMed search

Live results for "Glycine + NAC (GlyNAC) meta-analysis" across the PubMed/MEDLINE peer-reviewed index.

Key findings

Opens current human and preclinical literature matching Glycine + NAC (GlyNAC) and "meta-analysis". Filter by RCT, meta-analysis, or year on the results page.

Open study

Systematic reviewPubMed (NLM) · 1970

PubMed: Glycine + NAC (GlyNAC) — pharmacokinetics

Live PubMed search

Live results for "Glycine + NAC (GlyNAC) pharmacokinetics" across the PubMed/MEDLINE peer-reviewed index.

Key findings

Opens current human and preclinical literature matching Glycine + NAC (GlyNAC) and "pharmacokinetics". Filter by RCT, meta-analysis, or year on the results page.

Open study

Systematic reviewPubMed (NLM) · 1970

PubMed: Glycine + NAC (GlyNAC) — safety adverse events

Live PubMed search

Live results for "Glycine + NAC (GlyNAC) safety adverse events" across the PubMed/MEDLINE peer-reviewed index.

Key findings

Opens current human and preclinical literature matching Glycine + NAC (GlyNAC) and "safety adverse events". Filter by RCT, meta-analysis, or year on the results page.

Open study

Systematic reviewPubMed (NLM) · 1970

PubMed: Glycine + NAC (GlyNAC) — dose response

Live PubMed search

Live results for "Glycine + NAC (GlyNAC) dose response" across the PubMed/MEDLINE peer-reviewed index.

Key findings

Opens current human and preclinical literature matching Glycine + NAC (GlyNAC) and "dose response". Filter by RCT, meta-analysis, or year on the results page.

Open study

Systematic reviewGoogle Scholar · 1970

Google Scholar: Glycine + NAC (GlyNAC) — clinical evidence

Live Scholar search

Cross-database citation index for Glycine + NAC (GlyNAC) as it relates to "clinical evidence".

Key findings

Includes preprints, theses, and journal articles. Useful for tracking citation counts and follow-on work.

Open study

Educational use only. This profile is not medical advice. Consult a qualified healthcare professional before starting any supplement, especially if you take prescription medication or have a chronic condition.

Overview

Mechanism of action

Effects on the body

Organ system effects

Evidence-based benefits

Potential side effects

Drug interactions

Supplement interactions

Dosing & bioavailability

Where to buy

Community discussion