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AMINO ACIDS

N-Acetyl Cysteine (NAC)

Liver · antioxidant · respiratory

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Written to our editorial standards · reviewed against published research· Updated 2 Jun 2026
Last reviewed: May 30, 2026
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N-Acetyl Cysteine: Liver · antioxidant · respiratory. Precursor to glutathione, the body's master antioxidant. Supports liver detox, lung function, and recovery from oxidative stress. Standard dose 600 mg, taken in the morning, about $14/month. Evidence rating: strong evidence.

What is N-Acetyl Cysteine?

N-Acetyl Cysteine (NAC) is a stable, bioavailable form of the amino acid cysteine and the most-studied precursor to glutathione, the body's master antioxidant. By supporting glutathione production, NAC plays a central role in liver detoxification, lung mucus regulation, and protection against oxidative stress. With decades of clinical safety data, it is used by emergency departments to treat acetaminophen overdose. Daily supplementation may support respiratory health during cold and flu season, reduce oxidative damage from intense exercise, and help the liver process alcohol or environmental toxins. Most adults take 600-1,200 mg per day, ideally on an empty stomach.

WHY IT MATTERS

Precursor to glutathione, the body's master antioxidant. Supports liver detox, lung function, and recovery from oxidative stress.

Natural food sources

Where possible, get N-Acetyl Cysteine from whole foods first. Common dietary sources include:

Chicken & turkeyEggsYogurtGarlic & onionsLegumes

Where to buy

NOW Foods NAC 600mg
RECOMMENDED
NOW Foods, N-Acetyl Cysteine
600 mg · Morning · ~$14/month

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Best for your goal

Interactions

Other amino acids

L-Theanine (Suntheanine)
Calm focus · stress
Glycine
Sleep depth · core body temperature
Taurine
Heart · sleep · cellular hydration
Acetyl-L-Carnitine (ALCAR)
Brain energy · focus · fat metabolism

Common questions

What is N-Acetyl Cysteine?
N-Acetyl Cysteine (NAC) is a stable, bioavailable form of the amino acid cysteine and the most-studied precursor to glutathione, the body's master antioxidant. By supporting glutathione production, NAC plays a central role in liver detoxification, lung mucus regulation, and protection against oxidative stress. With decades of clinical safety data, it is used by emergency departments to treat acetaminophen overdose. Daily supplementation may support respiratory health during cold and flu season, reduce oxidative damage from intense exercise, and help the liver process alcohol or environmental toxins. Most adults take 600-1,200 mg per day, ideally on an empty stomach.
What is N-Acetyl Cysteine used for?
Liver · antioxidant · respiratory. Precursor to glutathione, the body's master antioxidant. Supports liver detox, lung function, and recovery from oxidative stress.
What is the standard dose of N-Acetyl Cysteine?
600 mg, typically taken in the morning. Approximate cost is $14 per month.
Who should avoid N-Acetyl Cysteine?
Use extra caution, and speak to a clinician first, if you are pregnant or nursing.
How strong is the evidence for N-Acetyl Cysteine?
Strong evidence for its primary uses. See the full study list on the research page.

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