Doctors in every emergency department in America know the name N-acetyl cysteine (NAC). This chemical derivative of cysteine, an amino acid, is administered more than 55,000 times a year as an antidote for an overdose of acetaminophen (Tylenol).
NAC is a lifesaver because it generates high levels of glutathione, a potent antioxidant that powers liver detoxification. (It’s the liver toxicity caused by overdoses of acetaminophen that sends so many Americans to the ER every year.) But NAC does much more than protect the liver.
By increasing levels of the antioxidant glutathione, NAC helps protect every cell in the body from free radicals. These renegade molecules are sparked by many causes, including processed foods and air pollution. In turn, free radicals cause cellular oxidation, a kind of internal rust that is linked to heart disease, cancer, arthritis, diabetes, Alzheimer’s disease, and many other chronic illnesses.
Pulmonologists routinely recommend NAC for patients with COPD because it makes mucus less viscous, more free-flowing, and more easily discharged.
In a meta-analysis of 15 studies published in the Annals of Palliative Medicine in June 2021, researchers reported that supplementing the diet with NAC improved symptoms in acute flares of COPD and improved lung capacity.
By reducing airway inflammation and thinning mucus, it can also improve asthma symptoms, according to researchers from the University of California, Davis. Further, the Mt. Sinai Medical System in New York recommends the supplement for some people with sinus infections.
While the science is evolving and not definitive, there are now more than a dozen scientific papers on the use of NAC in COVID-19.
In one of the most recent, published in the journal Infectious Diseases, researchers looked at 82 patients with COVID-19 who were hospitalized with pneumonia. Half of the patients took a daily dose of 600 milligrams (mg) of NAC, and half took a placebo. NAC was safe, and it appeared to significantly reduce the rate of respiratory failure leading to mechanical ventilation and significantly reduce the number of deaths.
NAC protects and strengthens the immune system in many ways:
A study published in the highly regarded European Respiratory Journal found that people taking NAC had less risk of getting sick when exposed to the flu virus than people who didn’t take the supplement.
NAC has a variety of heart-healthy benefits:
When scientists gave NAC to laboratory mice bred to develop dementia, it reversed memory loss, improved cognition, reduced the loss of neurons, and slowed the progression of Alzheimer’s disease, according to a study published in Brain Sciences. Successful treatment in laboratory animals does not always translate to success in humans, so much more research is needed before NAC is recommended for cognition.
There is human research on NAC and Parkinson’s disease (PD), though. Scientists reported in Clinical Pharmacology & Therapeutics that NAC appears to reduce PD symptoms by acting on the dopaminergic system.
In a meta-analysis published in The Australian and New Zealand Journal of Psychiatry, researchers reported that eight to 12 weeks of NAC supplementation significantly improved a range of symptoms and behaviors in people with autism spectrum disorder, including hyperactivity, irritability, and social awareness.
A team of researchers from Yale University reported that it appears to reduce the symptoms of obsessive-compulsive disorder.
Other research suggests that it has benefits for people with attention deficit hyperactivity disorder, depression, anxiety, and more.
Its possible mechanisms of action include the regulation of neurotransmitters (brain chemicals that control cognition and emotion), and reduction of oxidation and inflammation in brain cells.
A typical preventive or therapeutic daily dose of NAC is 1,200 to 1,800 mg taken in divided doses. Taking 600 mg two or three times daily or 900 mg twice daily keeps blood levels of glutathione steady and improves tolerability.
While NAC is safe at this dosage, some people experience stomach discomfort, akin to heartburn. If that happens, reduce the dose.
