NAC: One of the Best Supplements

For immune function and detoxification, plus liver health, mental health, and general health

For a while now, the amino acid derivative n-acetyl-cysteine (“NAC”) has been one of my favorite supplements.  It’ll decongest you, cut your cold or flu by about half, raise the antioxidant status of your liver and lungs, protect your kidneys from chemical injury, support detoxification of everything from mercury to acetaminophen to alcohol, and protect your eyes from degenerative damage.

So, yes, I liked NAC.  I took NAC.  And I thought I knew all there was to know about NAC (well, within reason, of course…).

So I was puzzled when, a few months back, a customer asked me how much NAC to take for obsessive-compulsive disorder.  I said I had no idea (and, I’m ashamed to admit, just assumed the customer was confused).  A few weeks later, another customer asked about using NAC in a different behavioral disorder, bipolar depression.  Once again: no clue.  But this time I decided to look into it.  I got on PubMed to see what I could find perhaps a small, inconclusive trial with a couple of mice? and was absolutely blown away by all the research that had been published since last I checked, maybe five years ago.

There was a trial where NAC reduced the urge in compulsive gamblers.  There was a trial where it helped teenage girls who compulsively pulled their hair (trichotillomania).  There was a trial where it improved depressive symptoms in bipolar disorder.  There were a number of trials showing benefit in schizophrenia.

Stepping away from behavioral issues, there was a trial where NAC improved semen quality in infertile men, and another where it helped women with a history of pre-term births carry their pregnancies to term[1].  There was a trial where it helped heal the colon in ulcerative colitis, and another where it restored lung function in people who had been exposed to mustard gas (that last one: research out of Iran).  It also reduced a number of lung cancer risk factors in smokers.  It improved immune function in AIDS patients (in two trials).  It reduced blood vessel damage in type II diabetes.  It reduced symptoms of polycystic ovarian syndrome.

I could go on.

And this was solid research.  Everything I just listed was an in vivo human trial, all double-blind except the gambling.  When I opened up the search results to include animal trials, the studies skyrocketed into the hundreds.

Turned out, one of my favorite supplements was… even better than I had thought!  There are very few things out there that are good for just about everyone.  Fish oil.  Fiber.  Green tea.  Reishi mushroom.  Coenzyme Q10.  A handful of others.  I now feel comfortable adding NAC to this exclusive group.

So it’s time to take a closer look at NAC, not just what it does because all I’d do is give you a 10-page list but how it actually works.


NAC does two things, basically.  First or at least easiest to explain is thin mucous.  The drug “Mucomyst,” for example, is just NAC in a buffer solution, atomized and inhaled directly into the lungs[2].

In direct contact, NAC dissolves mucous in split-seconds.  NAC also thins mucous when taken orally[3], although it won’t be quite so quick or dramatic: results are usually noticeable in about an hour, and they focus on, but are not limited to, the airways.  NAC is equally effective for congestion caused by infection, allergies, or chronic illness; leading to coughing, mouth-breathing or snoring.  And just to be clear, NAC does not reduce the production of mucous, just thins out what you’ve already got.  You shouldn’t have to worry about NAC over-drying you.

The end result is more than just comfort.  Mucous that’s too viscous thick, boggy and clotty hinders everything from an effective immune response in the airways, to breathing, to conception itself.


The other thing NAC does is a little harder to explain.  NAC raises the levels of a compound called glutathione in the body.  Most everything NAC does other than decongesting you can be traced directly to increased glutathione levels[4].

So what’s glutathione, then?


Glutathione is an endogenous antioxidant, which is to say an antioxidant we produce inside the body (as opposed to exogenous antioxidants, which we get from outside the body, usually by eating them).

Both endogenous and exogenous antioxidants are, generally speaking, good for us.  They neutralize toxic free radicals, and protect our cells from chemical damage.  But while exogenous antioxidants tend to be “aimless floaters” they’ll neutralize toxins, but only when they bump into them, accidentally endogenous antioxidants are produced by the body for very specific purposes.  And while exogenous antioxidants are, to a certain degree, interchangeable for example, antioxidants from red wine can neutralize the same toxins as antioxidants from green tea endogenous antioxidants are produced to handle tasks that nothing else can handle.

And glutathione is arguably our most important endogenous antioxidant.

Glutathione is central to the most important detoxification pathway in the liver.  The importance of this cannot be overstated.  When people are wheeled into hospitals in the United States after an overdose of a liver-toxic drug like acetominophen, intraveinous NAC is given, and if it’s given quickly enough, its ability to restore hepatic glutathione saves their lives.

Glutathione helps the lungs, kidneys, and gut deal with toxins as well.  It’s involved throughout the body in something called the glutathione-metallothionein axis, which is our primary mechanism for detoxifying heavy metals like mercury.  It protects the walls of the gut from inflammatory and chemical damage.  It protects the delicate tissues inside the eyes from degradation induced by various toxins.

And please understand, the toxins I’m talking about aren’t necessarily the result of us being “poisoned,” either acutely, or by the insidious effects of pollution.  They’re an unavoidable part of everyday life.  We’re always exposed to things that aren’t good for us; many are even produced inside the body, as byproducts of sun exposure, exercise, and normal cellular metabolism.  Glutathione is crucial.

The Brain:

Glutathione is as important in the brain as it is in the rest of the body, where it once again protects the tissues from damage, and mops up damage that has already occurred.  But what I hadn’t understood until recently was how important glutathione and by extension, NAC could be, regardless of toxins.

Glutathione modulates activity of a neurotransmitter called glutamate.   Excess glutamate activity is involved in obsessive and compulsive behaviors, as well as the startle response in anxiety.  You might say that glutathione “lowers” glutamate, but that’s not entirely true.  Rather, glutathione helps take excess glutamate out of play quicker.

This might not be the entire explanation for the clinical results with NAC, but at least it’s a start.  And the results sure are impressive.  In addition to the human trials I already mentioned, there was a study with cocaine-addicted mice, who were able to stay off the drugs better when they were give NAC.  There was a study with heroin-addicted mice where their withdrawal from the drug was a lot less painful when they were pre-treated with NAC.  So far, I’ve gotten feedback from two people who’ve used NAC for compulsive disorders.  Both felt that a dose of 1,200-1,800 mg a day was starting to show highly significant results by the third month.  I’m eager to see how it works for more people.

Immune Function:

And finally, I should touch on NAC and immune function… or maybe I shouldn’t.  It’s kind of hard to explain all the complicated stuff going on.  Let’s just say that glutathione and thus, NAC helps the immune system function more efficiently on a number of levels.

Stepping out of the lab and into the clinic, we see NAC flat-out working.  In one trial, involving 262 senior citizens in 20 treatment centers throughout Italy, 600 mg of NAC daily for six months dramatically slashed the incidence of flu symptoms.  Both the NAC and the placebo group were equally likely to have been exposed to the flu.  But of those exposed, only 25% of the group receiving the NAC developed symptoms, vs. 79% in the placebo group.


A standard dose for just about any chronic purpose is 1,200-1,800 mg daily in divided doses.  For acute use fighting off a cold, or maybe you’ve just been breathing fumes all day long 3-5,000 mg a day would be appropriate.

[1] Implying, obviously, that NAC is safe during pregnancy.  It’s nice to have a cold’n’flu treatment that’s safe during pregnancy!  For what it’s worth, look also at the coconut derivative Monolaurin, especially for the flu.

[2] This makes NAC one of the rare substances that is available both as a “drug” and a “supplement” in the United States.  Fish oil, potassium, and vitamin D are others.  The regulatory distinctions between the two categories are at times arcane and at times silly.  Suffice it to say, it’s the same stuff either way.

[3] It would seem reasonable to worry about this, since mucous is what protects our stomachs against their own acid.  All I can say is, in the real world in both clinical trials and my own experience NAC doesn’t seem to create problems here.

[4] You can also buy glutathione supplements, but they tend to get digested, and are not absorbed intact.  For the most part, the best way to raise glutathione is to take things that raise glutathione, rather than take glutathione itself.

Other compounds that provide the building blocks for glutathione synthesis include alpha-lipoic acid, and sulfur-rich protein, most notably dairy whey.  Vitamin C and selenium catalyze glutathione synthesis.  The sleep hormone, melatonin, stimulates glutathione synthesis.  Most herbs that are protective of the lungs and liver can be shown to induce glutathione synthesis in those areas specifically.

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