Cysteine / N-acetyl-cysteine (NAC)

N-Acetyl Cysteine (NAC) is the pre-acetylized form of the simple amino acid cysteine. It is a powerful antioxidant, a premier antitoxin and immune support substance, and is found naturally in foods. It is a precursor for glutathione, along with glutamine and glycine, an important antioxidant that protects cells against oxidative stress. In addition to maintaining intracellular glutathione levels, NAC supplementation has been shown to suppresses HIV replication, to be protective against cell damage caused by chemotherapy and radiation therapy, to be immune enhancing, to protect against toxins as acetamenaphen and other drugs, mercury, lead, and others, and is mucolytic, that is, it breaks up mucus seen in bronchopulmonary disease as cystic fibrosis, chronic bronchitis, asthma, and pneumonia.

NAC has all the properties of L-Cysteine but is more water soluble and said to be more bioavailable than L-Cysteine. It is known and marketed as an “anti-amalgam” medicine, because it helps remove mercury from the body. It also generally improves the body’s immune system, making it better able to fight off disease. It is freely available from health-food shops in many countries. NAC has neither a sedative or stimulant effect, and is a safe substance showing excellent tolerance in patients.


Cysteine / N-acetyl-cysteine (NAC) can help with the following


Parkinson's Disease / Risk

Both cysteine and NAC increase glutathione levels.


Allergic Rhinitis / Hay Fever

N-acetylcysteine is recommended at 200mg three times per day.

Environment / Toxicity  

Mercury Toxicity / Amalgam Illness

The ability of NAC to enhance methylmercury excretion when given orally, its relatively low toxicity, and its wide availability in the clinical setting indicate that it may be an ideal therapeutic agent for use in methylmercury poisoning. [Environ Health Perspectives, 1998, 106(5): pp.267-71] Earlier concerns over NAC causing mercury to accumulate in the brain and kidneys, as can occur with L-cysteine, now appear to be unfounded. The initial concerns were opinions only, based on L-cysteine research, not NAC research. Still, some clinicians feel that symptom worsening occurs with the use of large doses of NAC (over 300mg per day), especially if they already have elevated levels of L-cysteine. If L-cysteine levels are elevated, cystiene containing products like protein powders should be avoided.


Dupuytren's Contracture

Here is some information from this site:

In laboratory experiments NAC can slow down growth of Dupuytren cells (Juergen Kopp et al. “N-Acetyl-L-Cysteine abrogates fibrogenic properties of fibroblasts isolated from Dupuytren’s disease by blunting TGF-ß signalling” J. Cell. Mol. Med. 10 (2006) pp. 157-165, see also our page on NAC therapy. It is unclear to whether the laboratory concentration levels of NAC can be achieved in a real hand and to what extent lower concentrations would be beneficial. As far as we know there are no clinical results available about the effect of NAC on Dupuytren’s contracture (Dupuytren’s disease) or Ledderhose disease in real life. Therefore we, in cooperation with Dr. Charles Eaton of the Florida handcenter, collected reports from Dupuytren patients who are taking NAC or have taken NAC. Here are the results (data collection ended October 2007).

A total of 10 patients participated initially. Three patients stopped taking NAC (brand name e.g. ACC) after less than one month. Below are the reasons for stopping to take NAC:

– one patient because of continuing stomach problems after 1 week of NAC

– one patient because of permanent fatigue

– one patient for private reasons.

Patients’ details:

7 patients have taken NAC for more than 1 month. Below percentages refer to a total of 7. Please note that a total of 7 doesn’t provide very reliable statistics, the percentages are below thus not to be taken for granted. – All of those 7 patients were male.

Age: 42 – 60 (average = 51.5)

Stage of disease: all patients suffered from Dupuytrens, 43 % additionally from Ledderhose, 14 % also from Peyronie. Most patients had one or more surgeries already.

Dose: typically 600 mg NAC/day; 1 patient temporarily takes 1 g /day

Application period: 3 – 6 months.

Positive results:

– typically not much change in the first 2-3 months but situation stable

– after 3-5 months 86 % of the patients report that their nodules became somewhat softer

– one patient (14 %) reports that his Ledderhose nodules became softer after 3 months but that his Dupuytren cords kept growing slowly. Another patient reports of a growing cord after 5 months.

– one patient reports after 5 months that his Dupuytren nodule shrank to about 2/3 its initial size. Another patient reports after 3 months that his Dupuytren nodules became “somewhat smaller”.

– one patient reports that his grip improved after 4 months.


Taking NAC over 2+ months seems to soften nodules. Nodules seem to grow slower or might in favorable cases even shrink to some extent. Cords seem to continue growing but possibly slower. We have no reports what happens when taking NAC is discontinued.

A better controlled clinical research might make sense as next step. Dr. Eaton suggested that taking NAC orally might not be sufficient to achieve high concentration at the tumor itself. Other means of application might be more efficient and worth investigation.

Observed side effects:

One patient reported an initially aching stomach. See also above reasons for stopping to take NAC.

Organ Health  

COPD (Chronic Obstructive Pulmonary Disease)

Oxidative stress is closely linked to inflammation. The inflammatory process in patients with stable COPD is dominated by macrophages, CD8+ T-lymphocytes and neutrophils, and to a lesser extent mast cells, in the bronchial submucosa and alveoli 5. Increased production of mediators, such as interleukin (IL)-8, tumour necrosis factor- (TNF-) and leukotriene B4, which both attract inflammatory cells and increase oxidant production by these cells, has been found.

Attenuation of oxidative stress would be expected to result in reduced pulmonary damage and a decrease in local infections, contributing to attenuation of the progression of COPD. At present the only antioxidant widely available for the treatment of patients with COPD is N-acetylcysteine (NAC).

An open clinical trial including 1,392 patients demonstrated the efficacy of NAC at a dose of 600mg·day in reducing the viscosity of expectorations, promoting expectoration and reducing the severity of cough. After 2 months of treatment with NAC, the viscosity of expectorations improved in 80% of cases, the nature of the expectorations improved in 59%, difficulty in expectorating improved in 74% and the severity of cough improved in 71%. [J Int Med Res 1983;11:279–284]

Improvement in clinical symptoms as a result of treatment with NAC has been shown in a long-term double-blind trial with parallel groups conducted in several centres to which 744 patients with chronic bronchitis were recruited. Patients were randomly divided into two groups, one treated with NAC and the other with placebo. The results confirmed the efficacy of NAC regarding the parameters related to bronchial hypersecretion. [Eur J Respir Dis 1980;61: Suppl. 111, 93–108]



40 individuals with chronic posterior blepharitis were randomly assigned to receive standard therapy, either alone or in combination with oral NAC at 100mg tid for 8 weeks. The standard therapy was topical steroids and antibiotics, warm compresses to the eyelids twice a day, and the use of artificial tears. The group receiving NAC had a statistically significant improvement over the control group. These findings suggest that NAC could provide relief for individuals with this persistent and difficult-to-treat condition. [Cornea 2002;21: pp.164-8]


Kidney Failure

Oral treatment with acetylcysteine (400mg twice daily) reduced serum creatinine concentrations in a controlled study of 121 patients with chronic renal insufficiency. [J Am Coll Cardiol 2002;40(8): pp.1383-8]


May do some good
Likely to help



A nonessential amino acid but may be essential for individuals with certain diseases or nutritional concerns. Cysteine is a sulfur-bearing amino acid with antioxidant properties. It is important for keratin synthesis, a protein found in skin, hair and nails and is a component of coenzyme A and glutathione.


(N-acetyl-l-cysteine): A sulfur compound that is a precursor of glutathione.

Amino Acid

An organic acid containing nitrogen chemical building blocks that aid in the production of protein in the body. Eight of the twenty-two known amino acids are considered "essential," and must be obtained from dietary sources because the body can not synthesize them.


A chemical compound that slows or prevents oxygen from reacting with other compounds. Some antioxidants have been shown to have cancer-protecting potential because they neutralize free radicals. Examples include vitamins C and E, alpha lipoic acid, beta carotene, the minerals selenium, zinc, and germanium, superoxide dismutase (SOD), coenzyme Q10, catalase, and some amino acids, like cystiene. Other nutrient sources include grape seed extract, curcumin, gingko, green tea, olive leaf, policosanol and pycnogenol.


A natural sulfur-bearing peptide formed from the linking of three amino acids: glutamic acid, cysteine and glycine. Glutathione acts as an antioxidant and detoxicant and is involved with the selenium-containing enzyme glutathione peroxidase. Glutathione is also involved in amino acid transport across cell membranes.


A non-essential amino acid, glutamine is considered to be a brain fuel. Glutamine has been used therapeutically for alcoholism, mild depression and to reduce the craving for sweets. Glutamine is very important in the functioning of the metabolism and muscle maintenance. Glutamine supplementation can help prevent muscle and other tissue breakdown by providing the body with nitrogen and fuel.


The simplest amino acid which is a constituent of normal protein and an inhibitory neurotransmitter, used as a dietary supplement. A natural antacid and sweetener, it is involved in the syntheses of DNA, phospholipids and collagen.


Abbreviation for human immunodeficiency virus, a retrovirus associated with onset of advanced immunodeficiency syndrome (AIDS).


A treatment of disease by any chemicals. Used most often to refer to the chemical treatments used to combat cancer cells.


Agent breaking down or dissolving mucus.

Cystic Fibrosis

(CF) An incurable genetic disease involving a sticky buildup of mucus in the lungs (which makes breathing difficult and leads to infections), as well as pancreatic insufficiency (which leads to digestive problems). Symptoms include chronic cough producing thick mucus, excessive appetite combined with weight loss, intestinal disorders, salty sweat/skin and pneumonia. Lung-related problems are the most frequent cause of death. CF is a recessive disease, occurring only when a person inherits two mutated copies of the CF gene - one from each parent. Individuals with CF generally have a life expectancy of about 30 years.


Usually Chronic illness: Illness extending over a long period of time.


Inflammation of the mucous membrane of the bronchial tubes, frequently accompanied by cough, hypersecretion of mucus, and expectoration of sputum. Acute bronchitis is usually caused by an infectious agent and of short duration. Chronic bronchitis, generally the result of smoking, may also be known as Chronic Obstructive Pulmonary Disease (COPD) or Emphysema.


A lung disorder marked by attacks of breathing difficulty, wheezing, coughing, and thick mucus coming from the lungs. The episodes may be triggered by breathing foreign substances (allergens) or pollutants, infection, vigorous exercise, or emotional stress.

Immune System

A complex that protects the body from disease organisms and other foreign bodies. The system includes the humoral immune response and the cell-mediated response. The immune system also protects the body from invasion by making local barriers and inflammation.


Calming, quieting; drug that quiets nervous excitement.

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