N-acetylcysteineNAC
N-acetylcysteine is a stable form of the amino acid cysteine and a direct precursor of glutathione, the body’s most important antioxidant.
300 mg a day.
What it is
It has a long history as a medicine (a mucolytic and an antidote for paracetamol poisoning), and it is studied as a supplement for its antioxidant and insulin-sensitising action.
What it is used for
The quiz suggests it when your answers justify it. It usually appears with these goals:
What the evidence says
Early data in people or, mostly, from the laboratory. It only appears at the advanced level, and we say so.
A precursor of glutathione, the cell’s main antioxidant. In healthy people, the evidence is limited.
| Year | What was studied | What was found | Source |
|---|---|---|---|
| 2020 | Oxidative stress and inflammation | Meta-analysis of 28 trials: NAC lowered malondialdehyde (a marker of oxidative damage), IL-8 and homocysteine. It did not change CRP, and the effect on TNF-α and IL-6 only appeared when the analysis was repeated excluding some studies. | Faghfouri et al.European Journal of Pharmacology |
| 2023 | Glutathione in older people (combined with glycine) | Small trial: 24 older people for 16 weeks with glycine + NAC (GlyNAC) at per-kilo doses far higher than a supplement’s. It corrected glutathione deficiency and improved markers of oxidative stress, inflammation and physical function. It is the combination, not NAC alone. | Kumar et al.Journals of Gerontology: Series A |
What to look for on the label
- A supplement dose: 300 mg.
- In some EU countries it is considered a medicine.
Precautions
- If you have asthma or take nitroglycerin or anticoagulants, ask first.
Where to find it
Products whose label meets what this profile asks for: form, dose per serving and nothing that contradicts it. Three at most: quality of the active comes first and, among the best, we look for one option in each price range. We choose by composition, not by who pays. The shops are European or ship to Europe.
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HSNShips from SpainEssential Series
NAC 300 mg
300 mg per capsule
For the reference dose1 capsuleView at HSN (opens in a new tab)Meets the criteria. Adds selenium and vitamins E and B2.
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HSNShips from SpainRaw Series
NAC powder
Pure N-acetylcysteine
For the reference dose300 mg (half a scoop)View at HSN (opens in a new tab)Meets the criteria.
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iHerbShips from the US, VAT includedNOW Foods
NAC powder
Pure N-acetylcysteine, no excipients
For the reference dose300 mg (1/8 of a level teaspoon)View at iHerb (opens in a new tab)Meets the criteria.
We link to the shop; we do not sell anything. Today we earn no commission on any link. If we ever do, the link will say so and the selection will not change: the label decides. Labels checked on 2 November 2026; check the one on the pack before you buy. All these shops deliver to the EU; some of their pages open in Spanish. How we are funded.
Nearby in the library
Is it for you?
The quiz decides from your answers, not from a profile.
Profile reviewed on 3 November 2026. Sources: EFSA, Regulation (EU) 432/2012 and published studies. Image: Chemical apparatus. Engraving by J. Pass, 1801. Wellcome Collection, public domain.
General information based on published scientific evidence and EU law. Food supplements should not be used as a substitute for a varied, balanced diet and a healthy lifestyle, and are not intended to diagnose, treat or prevent any disease.
Do not exceed the daily dose stated on each product. If you take medication, have a medical condition or have any doubts, ask your doctor or pharmacist.