NAC

N-acetylcysteine (NAC) is a modified form of the amino acid cysteine. It has been used in medicine for over 50 years, primarily as an antidote for acetaminophen (paracetamol) overdose, where it is FDA-approved and life-saving when administered promptly.

NAC works primarily by replenishing glutathione, the body's most important antioxidant and detoxification compound. Glutathione neutralizes free radicals and binds to toxins for elimination. Unlike oral glutathione, which is poorly absorbed, NAC effectively raises glutathione levels when taken orally.

Beyond its emergency medical use, NAC has been studied for numerous conditions. It acts as a mucolytic (breaks down mucus) and is used for chronic respiratory conditions like COPD and bronchitis. It has shown promise in psychiatric conditions including OCD, bipolar disorder, and addiction. It also has emerging applications in metabolic syndrome, PCOS, and fertility.

NAC has excellent bioavailability and safety. Side effects are generally mild and primarily gastrointestinal. However, high doses can have a distinct sulfur/rotten egg smell and taste due to the cysteine content.

The compound gained significant public attention in 2020 when the FDA attempted to reclassify it as a drug rather than a dietary supplement due to its drug approval history, though it remains available as a supplement.

NAC exerts its effects through multiple mechanisms:

1. Glutathione Precursor: NAC is efficiently absorbed and metabolized to cysteine, which is the rate-limiting precursor for glutathione synthesis. By providing cysteine, NAC restores and maintains glutathione levels depleted by oxidative stress, toxins, or acetaminophen overdose.

2. Mucolytic Action: NAC breaks disulfide bonds in mucus glycoproteins, reducing mucus viscosity and making it easier to clear from airways. This is particularly useful in chronic bronchitis and COPD.

3. Glutamate Modulation: NAC appears to modulate glutamate in the brain, potentially through the cystine-glutamate antiporter. This may explain its effects on compulsive and addictive behaviors, as glutamate dysregulation is implicated in these conditions.

4. Anti-inflammatory Effects: NAC can reduce inflammatory cytokine production and NF-κB activation, contributing to its benefits in inflammatory conditions.

5. Direct Antioxidant: NAC itself has direct antioxidant properties, scavenging free radicals independent of its role in glutathione synthesis.

6. Chelating Agent: NAC can bind to heavy metals, potentially aiding in their elimination from the body.

7. Mitochondrial Support: By reducing oxidative stress, NAC may protect mitochondrial function and support cellular energy production.

NAC is not found in foods; it is a modified amino acid produced synthetically. Cysteine is found in protein-rich foods but in lower bioavailable forms.

No established RDA. Doses vary by indication: 600-1800 mg daily for respiratory conditions; 1200-2400 mg for psychiatric conditions; 6000+ mg for acetaminophen overdose (medical supervision).

NAC is available as oral capsules/tablets and effervescent tablets. Oral bioavailability is approximately 4-10% but sufficient to raise glutathione levels.