© 1991-2014 Jerry Emanuelson


N-Acetyl-Cysteine (NAC) is an important life extension supplement.  It is an acetylated form of the amino acid cysteine.  NAC is a potent antioxidant.

  • NAC is used by the body to make glutathione peroxidase, one of the body's most important naturally occurring antioxidants.  NAC raises glutathione levels better than taking supplemental glutathione.

  • NAC is an excellent mucolytic agent.  It keeps the membranes of the respiratory system moist, thereby lessening the irritation of dry air, dust, and pollutants.  It also helps the immune system to do its job properly in the respiratory tract.  NAC is available as a prescription drug for this purpose, but you can buy NAC in a health food store for far less money.

  • The cysteine in NAC is an essential component in hair and nails.  Some people find that it enhances nail growth and makes nails less brittle.

  • NAC helps to prevent damage by aldehydes, which are breakdown products of alcohol [and of the small, but potentially harmful, amounts of methanol produced by aspartame (Nutrasweet)].

  • NAC can help to prevent damage to the liver caused from overuse of acetaminophen (Tylenol).  NAC is the standard treatment for acetaminophen overdose.  It is prudent to take NAC whenever one uses acetaminophen.  (Acetaminophen is known as paracetamol outside the United States.)

  • NAC increases blood levels of erythropoietin, a hormone that stimulates red blood cell production.  Taking NAC, along with fairly large oral doses of folic acid and vitamin B12 (about 5 mg. per day of each), may increase hemoglobin levels and bring mild cases of anemia into the normal range.  Increasing hemoglobin levels also requires an adequate production of testosterone and adequate amounts of iron (although too much iron is dangerous).

  • NAC is a chelator of heavy metals.  In other words, NAC binds to toxic heavy metals such as mercury and lead, and removes them from the body.  This is a slow process, but most chelating agents, such as EDTA, must be given intravenously.  NAC is one of the most effective oral chelating agents.  Taken regularly over a period of time, NAC will remove many toxic heavy metals from the body.  Toxic metals can accumulate in the body over time from many sources such as drinking water and possibly even from tooth fillings made of silver-mercury amalgam.  These heavy metals catalyze free-radical reactions.  (Free-radical reactions are the dangerous chemical reactions that are prevented by antioxidants.)  When certain heavy metals catalyze these free-radical reactions, they initiate free-radical reactions without being used up during the reaction.  So these heavy metals continue to cause free radical damage as long as they are present in the body.

It is recommended that persons taking the amino acid cysteine take at least three times as much vitamin C as cysteine to prevent the possibility of oxidized cysteine forming kidney stones.  N-Acetyl-Cysteine is much more stable and resistant to being oxidized to an insoluble form.  Nevertheless, it is wise to take at least as much vitamin C as N-Acetyl-Cysteine.  (Diabetics should consult their physician before using N-Acetyl-Cysteine, since it may have an insulin-blocking effect.)

Typical supplemental doses of N-Acetyl-Cysteine are 500-1500 mg. per day.


Kelly, G.S.  Clinical Applications of N-Acetylcysteine.  Alternative Medicine Review.  April 1998. Volume 3. Issue 2. pp. 114-127.

Millea, P.J.  N-Acetylcysteine:  Multiple Clinical Applications.  American Family Physician.  August 1 2009. Volume 80. Issue 3. pp. 265-269.

Suziki, K.  Anti-oxidants for therapeutic use:  why are only a few drugs in clinical use?  Advanced Drug Delivery Reviews.  April 28 2009. Volume 61. Issue 4. pp. 287-289.

Baker, W.L., and others.  Use of N-acetylcysteine to reduce post-cardiothoracic surgery complications:  a meta-analysis.  European Journal of Cardio-Thoracic Surgery.  March, 2009. Volume 35. Issue 3. pp. 521-527.

Dodd, S., and others.  N-acetylcysteine for antioxidant therapy:  pharmacology and clinical utility.  Expert Opinion on Biological Therapy.  December 2008. Volume 8. Issue 12. pp. 1955-1962.

Heard, K.J.  Acetylcysteine for Acetaminophen Poisoning.  New England Journal of Medicine.  July 17, 2008. Volume 359. Issue 3. pp. 285-292.

Hildebrandt, W., and others.  Effect of N-acetyl-cysteine on the hypoxic ventilatory response and erythropoietin production: linkage between plasma thiol redox state and O2 chemosensitivity.  Blood Journal.  March 1, 2002. Volume 99. Issue 5. pp. 1552-1555.

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