Product Information

Synonyms: NAC

Keywords: cardiovascular, bronchitis, emphysema, aging, diabetes, depression, asthma, fatigue, neuropathy, HIV, hepatitis, Alzheimer’s, memory, hearing


N-acetylcysteine (NAC) is a substance which is converted in the body to the amino acid L-cysteine. For reasons that are poorly understood, L-cysteine itself is neurotoxic when taken as a supplement; this toxicity is avoided by using NAC instead.1

L-cysteine, like the other standard amino acids, is a building block for the production of countless proteins needed by the body: enzymes, structural proteins, signalling molecules and their receptors, and a number of small polypeptide molecules with specialized functions. One such polypeptide is the tripeptide called ‘glutathione’ (GSH), a very important antioxidant that protects cells from being damaged or killed by certain metabolic byproducts.2

While NAC supplementation undoubtedly provides the body with all the benefits that derive from L-cysteine, the principal reason it is used as a supplement is to raise glutathione levels.


A good review of NAC and its medical applications is the one by Thorne Research3. Since NAC is a precursor for the body’s production of glutathione, Wikipedia’s article on glutathione2 is relevant for understanding why NAC has such a broad range of actions. The review by Arakawa and Ito4, of NAC’s value in preventing or treating neurodegenerative diseases, also makes good reading. A technically written review of what is known about NAC’s mechanisms of action is found in the article by Zafarullah, et al.5

What we can’t tell you

In the U.S. and some other industrialized countries, government agencies like the U.S. Food and Drug Administration have adopted censorship as a method for intensifying their control over the supplement industry and its customers. Thus, FDA regulations prohibit us from telling you that any of our products are effective as medical treatments, even if they are, in fact, effective.

Accordingly, we will limit our discussion of N-acetylcysteine to a brief summary of relevant research, and let you draw your own conclusions about what medical conditions it may be effective in treating.

NAC’s remarkable biological benefits

NAC is one of the most studied of all supplements. Interest in it began during the 1960s when it was found to be useful as a ‘mucolytic’ agent — i.e., it lowers the viscosity of mucus in the respiratory tract, assisting people with cystic fibrosis and other pulmonary ailments.6 In the early 1990s medical researchers took a strong interest in it as an anti-HIV treatment,7 and it has been in the spotlight ever since.

The list of medical applications of NAC is a very long one, as can be seen from the outline that follows.

Pulmonary and respiratory ailments:

  • acute respiratory distress syndrome (ARDS)8
  • asthma9
  • bronchitis10
  • emphysema
  • Chronic Obstructive Pulmonary Disease (COPD)11,12,10,13,14,15
  • ideopulmonary fibrosis16,17,18,19
  • cystic fibrosis6,20

Accelerated aging:

  • diabetes-related or Alzheimer’s-related tissue aging21
  • mitochondrial aging22

Neurodegenerative diseases:4,23

  • Amyotrophic Lateral Sclerosis (ALS)24
  • multiple sclerosis25
  • Alzheimer’s26,27,28,29
  • diabetic neuropathy30
  • diabetic retinopathy31
  • amlyoid-related brain cell loss
  • adrenoleukodystrophy32

Other neurological conditions:

  • bipolar disorder33
  • depression33
  • autism33
  • attention deficit hyperactivity disorder33
  • memory loss27
  • hearing loss34
  • chronic fatigue syndrome35
  • pain36
  • brain damage from stroke37
  • myclonus epilepsy38

Muscle-degenerative conditions:

  • Duchenne muscular dystrophy39
  • age-related muscle loss40


  • oxidation-related cancer41
  • anti-angiogenesis therapy42
  • prostate cancer43
  • tobacco-related lung cancer44
  • chemotherapy damage to lungs45

Cardiovascular ailments:

  • atherosclerosis46
  • high homocysteine levels47
  • artery damage from tobacco smoke48
  • blood clots49
  • impaired heart function after heart attack50
  • sclerodermic Raynaud’s phenomenon51
  • kidney-related cardiovascular disease52


Immune system problems:

  • immune suppression58
  • Sjögren’s syndrome59
  • systemic inflammation


  • malaria60
  • HIV7
  • influenza61
  • hepatitis C62,63
  • ulcers due to Helicobacter pylori64
  • bacterial infections with systemic inflammation65
  • sepsis66,67


  • acetaminophen (Tylenol®) overdoses68
  • mushroom poisoning69
  • zinc-related neurotoxicity70

Other applications:

  • diabetes71,21
  • cysteine/glutathione deficiency72
  • muscle fatigue73,74
  • non-alcholic fatty liver disease75,76,77
  • sickle cell disease78

These are far too many applications to discuss in detail, so let us just look at one of them, as an example of the medical power of this supplement: the prevention of vascular damage caused by dietary AGEs — chemicals created in food by cooking.

NAC interferes with cardiovascular damage

Whenever food is cooked, some of the sugars in the food are converted into substances called ‘AGEs’ (Advanced Glycation Endproducts).79 These are inflammatory chemicals that, when consumed, cause damage to the walls of arteries and veins, as well as accelerated aging in other tissues in the body. The body actually produces its own AGEs, but usually in smaller amounts than are found in the diet. Diabetics, however, often have higher levels of sugar in their blood, and so AGEs are produced in larger amounts in these people. The total AGE burden is therefore much higher in diabetics.

In an important 2004 paper, researchers at Mount Sinai School of Medicine showed that diabetics experience substantially less damage to arteries when their consumption of AGEs is reduced.21 The research also showed that NAC interferes with a key process through which AGEs produce inflammation and tissue damage. Interestingly, this research project was motivated by the idea that atherosclerosis can be prevented by reducing dietary AGEs, not the idea that NAC can be used to counteract the effects of high AGE consumption. Yet NAC did, in fact, prevent AGEs from damaging vascular cells.

This is just one example of NAC’s far-ranging effects on harmful processes taking place in the body. NAC is an inexpensive supplement that is safe and easy to obtain — so it would be foolish not to take advantage of it.


Are N-acetylcysteine supplements useful for the conditions and purposes mentioned above? We aren’t allowed to tell you, so you should take a look at some of the references cited here, and then decide for yourself.

30510 600 mg 120 capsules 1-3 capsules $17.45
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Pronunciation: acetyl a·sēʹ·təl, cysteine sısʹ·te·ēn

— RM

Last modified 2010.08.30