This interesting nutrient is made from the amino acid cysteine joined to an acetyl group. Acetylcysteine, also spelled as N-Acetyl-L-Cysteine, is a strong antioxidant. It donates the amino acid cysteine to help form the antioxidant glutathione. Glutathione is a powerful antioxidant normally found in the body. the proper dosage for long term health is not known but would be about one 500 mg capsule twice a week. You can use this supplement at a 500 mg dosage daily if you take a week off every other week. As with many supplements we don't know the effects when taken for several months or years. Therefore, taking breaks is a good idea.

N Acetyl Cysteine pill supplement

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An excellent review article in the April 1998 issue of Alternative Medicine Reviews summarizes the known effects of acetylcysteine. The author writes, “N-acetylcysteine is an excellent source of sulfhydryl groups, and is converted in the body into metabolites capable of stimulating glutathione synthesis, promoting detoxification, and acting directly as a free radical scavenger. Administration of acetylcysteine has historically been as a mucolytic [mucus dissolving] agent in a variety of respiratory illnesses; however, it appears to also have beneficial effects in conditions characterized by decreased glutathione or oxidative stress, such as HIV infection, cancer, heart disease, and cigarette smoking.” For more details, see acetylcysteine information.

Side effects of acetylcysteine
Other than large doses causing nausea, acetylcysteine is a safe nutrient. Some people have nausea for a few minutes within an hour of taking three 600 mg pills on an empty stomach.

How often to take a N-acetylcysteine supplement
Acetyl-L-Cysteine is a potent antioxidant. So potent that it is used in hospitals by the intravenous route to protect the liver from Tylenol (acetaminophen) overdose. Acetylcysteine can be used a few times a week. If you take daily acetaminophen for arthritis pain or other reasons, discuss with your doctor whether acetylcysteine could be helpful to you. Acetylcysteine can be taken together with other antioxidants such as vitamins C and E, and alpha lipoic acid, however you would need to lower your dose of the other antioxidants. For long term use, 3 times a week is appropriate.

Acetylcysteine Recommendations
Acetylcysteine is sold in dosages ranging from 250 to 600 mg. Acetylcysteine can help form the powerful antioxidant glutathione but the formation of glutathione synthesis is under feedback control. Administration of acetylcysteine with the resulting increase in glutathione levels may cause a feedback inhibition in glutathione synthesis. Thus, it may be best to take acetylcysteine every other day. The use of acetylcysteine certainly should be considered as an additional supplement in protecting various cells from damage in the elderly and those with Parkinson’s disease. If you are planning to use acetylcysteine along with other antioxidants, limit your daily dosage to 100 to 500 mg and don’t take it all the time. Acetylcysteine could protect the liver of those who take acetaminophen on a regular basis.
   Acetylcysteine is a good supplement to use to prevent Tylenol toxicity.

Acetylcysteine and prolonged physical activity
N-acetylcysteine enhances muscle cysteine and glutathione availability and attenuates fatigue during prolonged exercise in endurance-trained individuals.
Medved I.  Victoria University of Technology, Melbourne, Victoria, Australia.
J Appl Physiol. 2004 Jun 11
The production of reactive oxygen species in skeletal muscle is linked with muscle fatigue. This study investigated the effects of the antioxidant compound N-acetylcysteine on muscle cysteine, cystine and glutathione, and on time to fatigue during prolonged, submaximal exercise in endurance athletes. Eight males completed a double-blind, crossover study, receiving acetylcysteine or placebo before and during cycling for 45 min at 71%VO2peak, then to fatigue at 92%VO2peak. Acetylcysteine was intravenously infused at 125 mg.kg(-1).h(-1) for 15 min, then 25 mg.kg(-1).h(-1) for 20 min prior to and throughout exercise. Arterialized venous blood was analyzed for acetylcysteine, glutathione status and cysteine concentration. A vastus lateralis biopsy was taken pre-infusion, at 45 min exercise and fatigue and analysed for acetylcysteine, total glutathione (TGSH), reduced glutathione (GSH) cysteine and cystine. Time to fatigue at 92%VO2peak was reproducible in preliminary trials (CV 5.6+/-0.6%) and with acetylcysteine was enhanced by 26.3+/-9.1% (acetylcysteine 6.4+/-0.6 vs CON 5.3+/-0.7 min, P<0.05). Acetylcysteine increased muscle total and reduced NAC at both 45 min and fatigue (P<0.005). Muscle cysteine and cystine were unchanged during CON, but were elevated above pre-infusion levels with acetylcysteine. Muscle TGSH declined (P<0.05) and muscle GSH tended to decline (P=0.06) during exercise. Both were greater with acetylcysteine (P<0.05). Neither exercise nor NAC affected whole blood TGSH. Whilst blood GSH was decreased and calculated oxidised glutathione (cGSSG) increased with exercise (P<0.05), both were unaffected by NAC. In conclusion, acetylcysteine improved performance in well-trained individuals, with enhanced muscle cysteine and GSH availability a likely mechanism.

N Acetylcysteine and cocaine dependence
An open-label trial of N-acetylcysteine for the treatment of cocaine dependence: A pilot study.
Prog Neuropsychopharmacol Biol Psychiatry. 2006 Nov 16; Center for Drug and Alcohol Programs, Department of Psychiatry and Behavioral Sciences, Medical University of South Carolina, 67 President Street, Charleston, SC 29425,
Recent preclinical studies implicate N-acetylcysteine, a cysteine prodrug, as a potential medication for preventing relapse to cocaine use; however, little is known about the safety and tolerability of acetylcysteine in cocaine-dependent subjects in an outpatient setting. This pilot study examines the safety and tolerability of 3 doses of N-acetylcysteine for the treatment of cocaine dependence. Twenty three treatment-seeking cocaine-dependent patients participated in a 4-week medication trial and received N-acetylcysteine at doses of 1200 mg/day, 2400 mg/day or 3600 mg/day. Results suggested that the three doses were well tolerated. Overall, the retention rates appeared to favor higher doses of N-acetylcysteine (2400 mg/day and 3600 mg/day). The majority of subjects who completed the study (n=16) either terminated use of cocaine completely or significantly reduced their use of cocaine during treatment. Overall the findings suggest that it is feasible to treat cocaine-dependent treatment seekers with N-acetylcysteine on an outpatient basis.

Acetylcysteine pill questions
Q. Supplement like N-acetylcysteine pill as a precursor of glutathione, is an excellent antioxidant. My question is how much of the recommended dose is actually absorbed and forwarded to the liver (1st pass due to oral ingestion?) This is also a question about any other supplement, which, unlike pharmaceutical drugs, is not characterized by half life, absorption capability, protein binding percentage, etc. I am a lecturer at the University of Johannesburg in South Africa.
   A. Research with natural supplements is so early that we don't have enough data to answer these types of questions with any confidence.

Q. Which is preferable, Acetyl-l-Carnitine or n-acetylcysteine?
   A. Both are good antioxidants and small amounts of each could be helpful.

Q. Please let me know if you have had any feedbacks regarding vision problems as a result of n-acetylcysteine NAC supplement ingestion. Since a year ago I have temporary obstructed vision in my left eye. For a long time I had no idea why a fog like film would appear over night and then diminish over a period of about 6 to 8 weeks. I used to blame unknown ingredients in restaurant foods , but about a month ago I took n-acetylcysteine NAC to help relieve me of chest irritation and the next day the vision in my left eye went from relatively clear to virtually blind (only light, dark and faint colors visible). A check of several supplements by Pure Encapsulations which I have taken regularly showed small amounts of NAC n-acetylcysteine in their ingredients. This may explain the "unknown" causes of the temporary incidents of blindness. My eye doctors at Kaiser, Maui and at the Hawaii Eye Center in Honolulu insist the phenomenon is a "mature cataract" and recommend lens replacement. My concern is that the obstructing layer may not be in the lens but perhaps between the cornea and the lens, therefore rendering lens replacement useless in this particular case. My opinion is reinforced by the fact that by avoiding any supplements containing NAC n-acetylcysteine or other chelating ingredients the obstruction tends to clear up over time.
   A. We have not heard of any vision problems related to n-acetylcysteine NAC supplement use.

Q. Which is better to whiten olive skin? N-acetyl cysteine or plain glutathione? Should I take a combination of both?
   A. We are not aware of any research that shows skin pigmentation is decreased by taking oral n acetyl cysteine, oral glutathione pills, or applying such creams.

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