N-Acetyl Cysteine

Also indexed as: Acetylcysteine, NAC

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NAC (N-acetyl cysteine) is an altered form of the amino acid cysteine, which is commonly found in food and synthesised by the body.

Where is it found?

Cysteine, the amino acid from which NAC is derived, is found in most high-protein foods. NAC is not found in the diet.

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NAC has been used in connection with the following conditions (refer to the individual health concern for complete information):

Science Ratings Health Concerns
3Stars

Bronchitis (chronic)

Chronic obstructive pulmonary disease (COPD)

Paracetamol poisoning
2Stars

Angina pectoris

Gastritis

Heart attack (IV immediately following a myocardial infarction)

HIV support

Prevention of kidney damage during coronary angiography

Unverricht-Lundborg disease
1Star

Pseudoporphyria
3Stars Reliable and relatively consistent scientific data showing a substantial health benefit.
2Stars Contradictory, insufficient, or preliminary studies suggesting a health benefit or minimal health benefit.
1Star For a herb, supported by traditional use but minimal or no scientific evidence. For a supplement, little scientific support and/or minimal health benefit.
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Who is likely to be deficient?

Deficiencies of NAC have not been defined and may not exist. Deficiencies of the related amino acidcysteine have been reported in HIV-infected patients.1

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How much is usually taken?

Healthy people do not need to supplement NAC. Optimal levels of supplementation remain unknown, though much of the research uses 250–1,500 mg per day.

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Are there any side effects or interactions?

One study reported that 19% of people taking NAC orally experienced nausea, vomiting, headache, dry mouth, dizziness, or abdominal pain.2 These symptoms have not been consistently reported by other researchers, however.

Although a great deal of research has shown that NAC has anti-oxidant activity, one small study found that daily amounts of 1.2 grams or more could lead to increased oxidative stress.3 Extremely large amounts of cysteine, the amino acid from which NAC is derived, may be toxic to nerve cells in rats.

NAC may increase urinary zinc excretion.4 Therefore, supplemental zinc and copper should be added when supplementing with NAC for extended periods.

Are there any drug interactions?
Certain medicines may interact with N-Acetyl Cysteine. Refer to drug interactions for a list of those medicines.

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References
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