NAC
The most proven way to boost glutathione — your body's master antioxidant. NAC protects your liver, clears your lungs, and fights the oxidative damage that drives aging. Used in hospitals for 60+ years.
NAC is a supplement form of the amino acid cysteine. Your body uses cysteine to make glutathione — the antioxidant that protects your liver, lungs, and every cell from oxidative damage. NAC has been used as a medicine since the 1960s and is one of the most well-studied supplements available.
Good for you if: You have elevated liver enzymes, live in a polluted city, drink alcohol regularly, want to boost your antioxidant capacity, or are recovering from illness.
Dive deeper into the researchWatch out for
- Do NOT take with nitroglycerin or nitrate heart medications — dangerous blood pressure drop
- Can cause nausea at higher doses, especially on an empty stomach
- Space 2+ hours away from iron, zinc, and copper supplements
What does NAC do?
Think of glutathione as your body's cleanup crew — it neutralizes toxins, processes medications, and repairs oxidative damage in every cell. The problem is your body can't absorb glutathione supplements very well. They get broken down in your gut before reaching your cells.
NAC solves this by giving your cells the raw material (cysteine) they need to make their own glutathione exactly where it's needed. It's the same molecule hospitals use as the antidote for paracetamol overdose — because it rapidly restores the glutathione your liver burns through when processing the drug.
Beyond glutathione, NAC also thins mucus in your airways (useful for respiratory conditions and pollution exposure), reduces inflammation by calming the NF-κB pathway, and directly scavenges free radicals on its own.
What can you expect?
- Better liver numbers — ALT and AST often drop within 8–12 weeks at 600 mg twice daily
- Clearer breathing — NAC thins mucus and protects airways, especially relevant if you live in a polluted city
- Less oxidative stress — measurable reduction in oxidative damage markers
- Better recovery — after illness, heavy exercise, or alcohol consumption
- Immune support — glutathione is essential for proper immune cell function
How to take it
600 mg once or twice daily on an empty stomach. For liver support or respiratory health, 600 mg twice daily is the most studied protocol.
Food reduces absorption by ~30%, so take between meals when possible. If it causes nausea, take with a small amount of food. Space 2+ hours away from mineral supplements (iron, zinc, copper) — NAC can bind to them.
Cycling: Some practitioners suggest 5 days on, 2 days off, but evidence for mandatory cycling is limited. NAC works by supplying a substrate, not by overriding natural pathways, so continuous use is generally fine.
NAC vs glutathione — which should you take?
| Option | Absorption | Cost | Verdict |
|---|---|---|---|
| NAC | Absorbs intact, fuels glutathione inside cells | Affordable | Best choice for most people |
| Regular glutathione | Broken down in gut before absorption | Moderate | Mostly ineffective orally |
| Liposomal glutathione | Good — lipid coating protects it | 5–10× more expensive | Good but costly |
Want to see if NAC is actually working for you?
eterni tracks your liver enzymes and oxidative markers before and after — so you can see the improvement in numbers.
Get early accessFrequently Asked Questions
What does NAC actually do for your liver?
NAC gives your liver the building block it needs to make glutathione — the main molecule your liver uses to neutralize toxins, process medications, and handle oxidative stress. It's literally the antidote hospitals use for paracetamol (acetaminophen) overdose. For everyday use, 600 mg twice daily has been shown to reduce liver enzymes (ALT, AST) in people with fatty liver disease within 8–12 weeks.
Should I take NAC or glutathione supplements?
NAC is usually the better choice. Regular glutathione supplements get broken down in your gut before they can be absorbed. NAC passes through intact, enters your cells, and gets converted into the cysteine your body needs to make its own glutathione right where it's needed. It's also much cheaper. Liposomal glutathione does absorb better, but costs 5–10× more than NAC.
How much NAC should I take?
600 mg once or twice daily for general antioxidant support. For liver health or respiratory support, 600 mg twice daily is the most studied dose. Take on an empty stomach for best absorption — food reduces it by about 30%. Space at least 2 hours away from iron, zinc, or copper supplements, as NAC can bind to minerals.
Does NAC have any dangerous interactions?
Yes — one critical one. NAC significantly amplifies the effect of nitroglycerin and other nitrate heart medications, which can cause dangerous drops in blood pressure. If you take any heart medication, talk to your cardiologist before starting NAC. It may also mildly enhance blood-thinning effects of warfarin. Otherwise, NAC has 60+ years of clinical safety data.
How it works in your body
NAC is deacetylated to cysteine inside your cells. Cysteine then combines with glutamate and glycine to form glutathione — a process that's rate-limited by cysteine availability. This is why NAC works: it removes the bottleneck in glutathione production.
NAC also has direct antioxidant activity — its thiol (–SH) group scavenges hydroxyl radicals and other reactive species independently of glutathione. It reduces inflammation by modulating NF-κB signaling, and its mucolytic action (breaking disulfide bonds in mucus) explains its respiratory benefits.
An emerging area of research is NAC's effect on the cystine/glutamate transporter (xCT), which is relevant to its potential applications in OCD, addiction, and mood disorders at higher doses (1,200–2,400 mg/day).
What the studies show
- Fatty liver (NAFLD): 600 mg twice daily reduces ALT and AST and improves hepatic steatosis scores in multiple RCTs — highly relevant given ~38% NAFLD prevalence in urban India
- Respiratory health: A Cochrane review of 30+ RCTs found 600–1,200 mg/day significantly reduces COPD exacerbations (NNT ~5) and days of illness in chronic bronchitis
- Pollution protection: Studies in high-pollution areas show NAC reduces oxidative DNA damage markers and inflammatory cytokines
- Paracetamol overdose: The gold standard treatment worldwide — NAC restores hepatic glutathione within hours
- Psychiatric applications: Emerging evidence for OCD, addiction, and depression at 1,200–2,400 mg/day — moderate quality
Side effects & safety
- GI effects — Nausea and stomach upset at higher doses, especially on an empty stomach. Starting at 600 mg and working up helps.
- Nitrate interaction (CRITICAL) — NAC potentiates nitroglycerin and isosorbide dinitrate, causing severe hypotension. Never combine these.
- Anticoagulant effect — Mild antiplatelet effects; use cautiously with warfarin.
- Mineral chelation — NAC's thiol group can bind to iron, zinc, and copper. Space supplements 2+ hours apart.
- Asthma caution — IV NAC can cause bronchospasm; oral form is generally safer but use with medical supervision if asthmatic.
NAC significantly potentiates nitrate medications (nitroglycerin, isosorbide dinitrate) used for angina and heart failure. This combination can cause severe, sudden drops in blood pressure. If you are on any cardiac medication, consult your cardiologist before taking NAC.
Which labs to check
- Liver enzymes (ALT, AST, GGT) — the primary markers for tracking NAC's liver benefits
- Glutathione (if available) — direct measurement of what NAC is boosting
- hsCRP — systemic inflammation marker that should improve with NAC
- Complete blood count — baseline immune function assessment
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