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N-acetyl Cysteine – What’s It All About?

by Dr. Jason Barker April 20, 2020

N-acetyl Cysteine – What’s It All About?


N-Acetyl Cysteine (NAC) is a modified version of the amino acid cysteine, which is found readily throughout the body.  Its main job is to help restore levels of a very important antioxidant found within our cells, known as glutathione. Glutathione is used by our body to fight off the damage caused by reactive oxygen species, otherwise known as free radicals.

NAC Helps Thin Mucus

NAC has been used in medicine for several decades now, yet still remains relatively unknown. In conventional medicine, it’s been used as a mucolytic (mucus-thinner) in people with lung diseases like chronic bronchitis, emphysema, chronic obstructive pulmonary disorder, and cystic fibrosis.

All of these are inflammatory conditions wherein the linings of the respiratory tract end up producing mucus in excessive amounts. 

Mucus is a good thing, however.  It helps moisturize and protect the delicate tissues of our respiratory and gastrointestinal tracts and contains several immune system chemicals to help kill and trap viruses and bacteria.  

However, we when become ill we end up secreting a lot of it - you know this if you ever had a cold, sinus infection, bronchitis or other similar infection!

NAC & Acetaminophen Poisoning

It’s also the go-to remedy for acetaminophen poisoning – acetaminophen (Tylenol) is a popular over the counter pain reliever and fever reducer. Given its popularity, overdose is extremely common, whereby it destroys liver cells and is one of the most common causes of liver damage and failure.

NAC is one of the go-to emergency medications in known cases of acetaminophen poisoning. 

Even if you use acetaminophen it still damages the liver even at suggested doses - it won't hurt to take it whenever you use Tylenol or acetaminophen. Otherwise, here are some  safer pain relievers without liver damage as a side effect!

NAC - Great for Athletes

For athletes, NAC should be one of your go-to supplements, for a couple of reasons.

Cold Weather

NAC is a potent antioxidant that's partial to lung tissue (thus its use in a variety of lung diseases). If you’re an athlete with asthma, NAC can work to limit the inflammation and damage that occurs in delicate lung tissue as a result of asthma.

Ever go on a run or ride on a cold winter day and get that hacking, “smoker’s cough” after? That’s because you’re lungs are sensitive to cold air and are now inflamed. Taking NAC immediately before and after a cold weather bout of exercise will limit the inflammatory damage in your lungs. We take a single 500mg capsule about 30 minutes before a cold workout, and immediately after. 


Newer studies show a performance benefit from taking NAC.  A handful of smaller studies have shown improved antioxidant levels and decreased inflammation that lead to improved cycling performance (1) and limited fatigue (2,3).

Interestingly, the benefits of NAC in these studies were found in endurance exercise situations; other studies show that NAC may actually hamper muscle recovery in short term/explosive exercise (such as strength training).

This is due to blunting of antioxidant-induced muscle regeneration. In other words, some amounts of oxidation are critical to exercise recovery and muscle repair (4) (this is a relatively new finding that is being explored).

So, taking NAC for it's protective effects in endurance exercise is probably a good idea, but if your main focus is on short, explosive-type activities (sprinting, strength training, etc), then NAC may not benefit your performance.

Adding NAC to your regimen may be a good idea if you’re an athlete with asthma, cold-sensitive lungs, if you exercise in an urban area with poor air quality or you're primarily a cold-weather, high altitude athletes (altitude can also negatively affect lung tissue and inflammation.

NAC and Polycystic Ovarian Syndrome (PCOS)

Women with PCOS can benefit from the insulin-sensitizing effects of NAC - it's been shown to lower circulating levels of insulin and when elevated insulin levels are decreased, this can also significantly lower testosterone levels as well. 

Women with PCOS should consider incorporating NAC into their treatment regimen for this reasons and in addition for its antioxidant and anti-inflammatory effects.  Women taking NAC also have improved fertility rates. 

NAC and Alcohol Ingestion

Similar to acetaminophen, alcohol can easily overwhelm the anti-oxidation systems of the liver and rapidly deplete glutathione in the organ. Taking NAC prior to, and after alcohol ingestion can lessen the damaging effects of alcohol on the liver and may also lessen the notorious 'hangover' from alcohol ingestion.


N-acetyl cysteine is one of the few nutritional supplements with far-reaching benefits in the body and is one that we recommend almost everyone incorporate into their supplement regimens. 


1. Med Sci Sports Exerc. 2014 Jun;46(6):1114-23.

2. J Appl Physiol (1985). 2004 Oct;97(4):1477-85.

3. Int J Sport Nutr Exerc Metab. 2011 Dec;21(6):451-61.

4. Am J Clin Nutr. 2013 Jul;98(1):233-45.

5. Obstet Gynecol Int.  2015; 2015: 817849.

Dr. Jason Barker
Dr. Jason Barker

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