NAC: The Most Useful Supplement You’ve Never Heard About

NAC sounds like it could be an acronym for some obscure scientific agency. Instead, it’s shorthand for one of the most important supplements that most people have never heard of—an all-natural super nutrient called N-acetylcysteine.

Thankfully, you don’t have to know how to pronounce this formidable-sounding name in order to benefit from this amino acid, which is useful as both an over the counter supplement and as a prescription drug that is used in hospitals every day.  

Why Virtually Every Hospital Stocks NAC

For more than thirty years, NAC has proven itself to be one of the safest, most effective, and versatile therapeutic agents available. Here are just a few of the ways this amazing compound is being used by the medical community:

  • NAC is widely used by hospitals as the antidote to treat acetaminophen toxicity. Acetaminophen, as you might be aware, is the active ingredient in Tylenol, and is also an ingredient in several prescription medications including Vicodin. Unfortunately, acetaminophen can poison the liver… a problem that sends over 78,000 people to the ER every year. Over 33,000 of these cases require hospitalization, and nearly 2,000 of these people die. NAC can save lives, and is used in hospitals to do just that.
  • NAC is used for its ability to thin the mucus. For this reason, both naturopathic physicians and conventional health practitioners prescribe it to treat respiratory conditions such as emphysema, COPD, bronchitis, pneumonia, sinusitis, and cystic fibrosis.
  • There is a growing body of evidence that NAC may be one of the best first lines of defense when it comes to treating many mental health disorders. There are several reasons why it is so promising. First, NAC is highly neuroprotective, because it is so effective in reducing inflammation and oxidative stress. Second, NAC is one of the few compounds that can cross the blood-brain barrier, which means it can help elevate glutathione levels in the cortex. Diminished levels of glutathione have been correlated with numerous mental health challenges including depression, obsessive-compulsive disorder, and addiction issues.
  • Studies show that NAC is very effective in warding off flus and colds and decreasing their symptoms. I frequently recommend it at the beginning of the flu season, and for those who struggle with catching every sickness that is going around.  

How NAC works

One of the main reasons why NAC is such a versatile compound is that it is a precursor (like a building block) for a vitally important antioxidant compound called Glutathione. Glutathione is a potent intracellular antioxidant that is used in many cellular processes, such as tissue rebuilding and repair, detoxification, and immune system regulation. Because NAC is a precursor to glutathione, consuming NAC will increase the levels of glutathione throughout the body.

Glutathione, the Mother of All Antioxidants

Glutathione’s capacity to fight inflammation and scavenge for free radicals is so impressive that it is often called “the mother of all antioxidants.” This effect has led to a new line of research that is investigating the use of NAC to counteract oxidative stress, which is known to damage cellular DNA and lead to the growth of cancer cells.

The most important clinical question that is arising from this research is whether NAC can slow or derail cancer growth. And recent findings, published in the journal Seminars in Oncology, are very encouraging, at least in terms of breast cancer.

As Professor Michael Lisanti, at the School of Environment and Life Sciences at the University of Salford in the UK explains, “Our idea was to repurpose an inexpensive FDA-approved drug [NAC], to examine if its antioxidant properties could target the feeding behavior of cancer cells.”

What Dr. Lisanti and his colleagues found is that NAC disrupted very particular biomarkers and proteins, which cancer cells need to aggressively divide and replicate. This is a pretty big deal because the researchers essentially found that NAC appears to “starve” tumor cells.

Results like this could be a huge step forward in the campaign against cancer. Needless to say, much more research is needed, but here are some other areas where studies are ongoing and NAC is demonstrating clinical benefits:

  • Improving energy
  • Boosting immunity
  • Mental sharpness (clearing up “brain fog”)
  • Increasing male fertility
  • Helping to regulate blood glucose levels
  • Supporting digestive health

Taking NAC

NAC is available in several different forms. In the hospital setting, it is used in IVs and as an inhalant… but the good news is that it is readily available as an oral supplement in a capsule that you can find over the counter in most health food stores, or the vitamin section of your local pharmacy.

I generally recommend that people take 1,800 milligrams (mg) per day in two or three divided dose of:

  • 600 mg 3X per day, or
  • 900 mg 2X per day

Unlike most nutritive supplements, NAC is best taken on an empty stomach (away from mealtimes).


Despite have a strong track record for safety and effectiveness as a therapeutic agent for many conditions, NAC is still far from being a household name (even in the medical community).

Glutathione deficiency is implicated in so many diseases, and the research is clear that boosting levels of this critical antioxidant can help prevent and repair cellular damage while improving cellular functioning, especially in the liver, the brain, and the immune system.   

That’s where NAC comes in. Dr. Kondala Atkuri of Stanford University puts it well when he writes, “NAC has been used successfully to treat glutathione deficiency in a wide range of infections, genetic defects and metabolic disorders.”

NAC’s credentials over the last 30 plus years are impressive enough, and new research continues to impress. For any of you who have ever been skeptical about the effectiveness of dietary supplements, the evidence on NAC will certainly change your mind.  

Be Well,

Dr. Josh