N-acetyl-L-cysteine

N-acetyl-L-cysteine (NAC) is a modified form of the amino acid cysteine and serves as a precursor to glutathione, the body's primary intracellular antioxidant. It exerts multiple biological effects, including potent mucolytic, antioxidant, and anti-inflammatory actions. NAC has well-established use in acetaminophen (paracetamol) overdose by replenishing hepatic glutathione stores and detoxifying reactive metabolites [3]. Beyond this, emerging evidence supports its role in modulating oxidative stress and inflammation in respiratory conditions such as chronic obstructive pulmonary disease, acute lung injury, and even in viral infections like COVID-19, where redox imbalance contributes to tissue damage [4][7]. NAC also shows promise in psychiatric and neurological conditions, including obsessive-compulsive disorder (OCD), where it modulates glutamatergic neurotransmission via the cystine-glutamate antiporter [6]. Additionally, preclinical and clinical studies suggest protective effects against pesticide-induced toxicity and endometriosis by reducing cellular proliferation and promoting a less inflammatory phenotype, without adverse effects on fertility [2][5]. Despite its widespread use, the natural occurrence of NAC in dietary sources such as Allium species remains controversial and unproven [1].