What is N-acetylcysteine (NAC)?

N-acetylcysteine is also known as acetylcysteine and consists of an important amino acid in the body called cysteine. N-acetylcysteine, commonly referred to as NAC, gets its name because it is an acetyl group attached to the amino group of the amino acid cysteine. NAC is an antioxidant that can be found in a variety of plants, particularly onions. N-acetylcysteine aids in the formation of the body’s most potent antioxidant, called glutathione (GSH). This is important because glutathione helps the body detoxify harmful chemicals that are ingested or chemicals that are naturally made within the body. Because of these detoxification properties, one of the main uses of NAC in the medical field is as an antidote for certain types of poisonings. This restoration process works by eliminating reactive oxygen species (ROS) that may be circulating in the blood stream. This process has many beneficial uses for our body’s systems.²

What are the uses of N-acetylcysteine?

Glutathione’s impact on reactive oxygen species is imperative to combat oxidative stress on cells. However, studies have shown that glutathione is poorly absorbed in the gastrointestinal tract, so people turn to NAC as a dietary supplement to get the antioxidant effects of glutathione.³

NAC is available in dietary supplements and as a generic drug. It has been used in medical settings since the 1960s and is on the World Health Organization’s List of 40 Essential Medicines. In the medical setting, NAC is well known for its use as an antidote for patients experiencing a Tylenol overdose. It may also commonly be used as a mucolytic agent to thin mucous secretions, especially for patients with chronic obstructive pulmonary disease (COPD) or other lung and airway disorders. For example, Mucomyst is a common brand of acetylcysteine used for the prevention of asthma attacks. Research has shown many other potential benefits of NAC that continue to be studied.

How is N-acetylcysteine supplied?

There are varying routes of administration that have been approved by the Food and Drug Administration (FDA), including injectable, intravenous, oral dissolving tablet, oral solution, and inhalation.² Many dietary and sports supplements claim the inclusion of NAC in their products and allege health benefits; however, the FDA does not regulate dietary or sports supplements to the same standards as food and drugs so the efficacy of the product is not always determined.¹

What are the takeaway points of N-acetylcysteine?

N-acetylcysteine has been proven to function as a mucolytic agent and as an antidote for Tylenol overdose. As a mucolytic (phlegm reducing) agent, NAC has a profound therapeutic effect on the respiratory tract, including sinus passages and lungs. There are many other potential benefits of NAC due to its antioxidant properties. While there have been a great deal of studies demonstrating the clinical utility of NAC, further clinical trials are needed to determine proper dosing, for specific conditions and in which populations.²

References:

1. Center for Food Safety and Applied Nutrition. Dietary Supplements. U.S. Food and Drug Administration. https://www.fda.gov/food/dietary-supplements. Published August 16, 2019. Accessed March 11, 2020.
2. Šalamon Š, Kramar B, Marolt TP, Poljšak B, Milisav I. Medical and Dietary Uses of N-Acetylcysteine. Antioxidants (Basel). 2019;8(5):111. Published 2019 Apr 28. doi:10.3390/antiox8050111
3. Schmitt B, Vicenzi M, Garrel C, Denis FM. Effects of N-acetylcysteine, oral glutathione (GSH) and a novel sublingual form of GSH on oxidative stress markers: A comparative crossover study. Redox Biol. 2015;6:198–205. doi:10.1016/j.redox.2015.07.012