1. Essential for making the powerful antioxidant glutathione: NAC is valued primarily for its role in antioxidant production. Along with two other amino acids — glutamine and glycine — NAC is necessary to make and replenish glutathione. Glutathione is one of the body’s most important antioxidants. It’s essential for immune health and for fighting cellular damage.

2. Helps with detoxification to prevent or diminish kidney and liver damage: NAC plays an important role in the body’s detoxification process. It can help prevent side effects of drugs and environmental toxins. In fact, intravenous NAC is given to people with an acetaminophen overdose to prevent or reduce kidney and liver damage.

Thanks to its antioxidant and anti-inflammatory benefits, NAC also has applications for other liver diseases.

3. Helps relieve symptoms of respiratory conditions: NAC can relieve symptoms of respiratory conditions by acting as an antioxidant and expectorant, loosening mucus in the air passageways.

As an antioxidant, NAC helps replenish glutathione levels in the lungs and reduces inflammation in the bronchial tubes and lung tissue. People with chronic obstructive pulmonary disease (COPD) experience long-term oxidative damage and inflammation of lung tissue, which causes airways to constrict, leading to shortness of breath and coughing.

NAC supplements have been used to improve COPD symptoms, exacerbations, and lung decline. A review of multiple studies found that 600mg of NAC twice a day significantly improved lung function and symptoms in those with stable COPD and that higher doses were more effective than lower ones. Patients with chronic bronchitis can also benefit from NAC. Bronchitis occurs when the mucous membranes in the lungs’ bronchial passageways become inflamed, swell, and shut off airways to the lungs. By thinning mucus in the bronchial tubes and boosting glutathione levels, NAC may help decrease the severity and frequency of wheezing, coughing, and respiratory attacks.

In addition to relieving COPD and bronchitis, NAC may improve other lung and respiratory tract conditions — such as cystic fibrosis, asthma, and pulmonary fibrosis — as well as symptoms of nasal and sinus congestion due to allergies or infections.

4. Immune function: NAC and glutathione also benefit immune health. Research on certain diseases associated with NAC and glutathione deficiency suggests that supplementing with NAC might improve — and potentially restore — immune function. This factor has been studied most in people with HIV. In two studies, NAC supplementation resulted in a significant increase in immune function, with an almost complete restoration of natural killer cells.

High levels of NAC in the body may also suppress HIV-1 reproduction.

An in vitro study indicated that in other immune-compromised situations, such as the flu, NAC may hamper the virus’s ability to replicate. This could potentially reduce the symptoms and duration of the illness. Similarly, older test-tube studies have linked NAC to cancer cell death and blocked cancer cell replication.