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N-Acetyl Cysteine

Uses

NAC (N-acetyl cysteine) is an altered form of the amino acid cysteine, which is commonly found in food and synthesized by the body.

What Are Star Ratings?

This supplement has been used in connection with the following health conditions:

Used for Why
3 Stars
Bronchitis
400 to 600 mg daily
NAC, which appears to work by reducing the thickness of mucus, has been shown to be a safe and effective treatment for chronic bronchitis.

A review of 39 clinical trials of (N-acetyl cysteine) found that 400 to 600 mg per day was a safe and effective treatment for chronic bronchitis. NAC supplementation was found to reduce the number of aggravations of the illness in almost 50% of people taking the supplement, compared with only 31% of those taking placebo. Smokers have also been found to benefit from taking NAC. In addition to helping break up mucus, NAC may reduce the elevated bacterial counts that are often seen in the lungs of smokers with chronic bronchitis. In another double-blind study, people with chronic bronchitis who took NAC showed an improved ability to expectorate and a reduction in cough severity. These benefits may result from NAC’s capacity to reduce the viscosity (thickness) of sputum.

3 Stars
Chronic Obstructive Pulmonary Disease
200 mg three times daily
N-acetyl cysteine helps break down mucus and supplies antioxidant protection to lung tissue.

(N-acetyl cysteine) helps break down mucus. For that reason, inhaled NAC is used in hospitals to treat bronchitis. NAC may also protect lung tissue through its antioxidant activity. Oral NAC, 200 mg taken three times per day, is also effective and improved symptoms in people with bronchitis in double-blind research. In other double-blind studies, oral NAC in the amount of 600 mg twice a day for 1 year significantly decreased the number of disease exacerbations in patients with moderate-to-severe COPD. However, NAC was ineffective in one study. Results may take six months. NAC does not appear to be effective for people with COPD who are taking inhaled steroid medications.

2 Stars
Angina
600 mg three times daily (under medical supervision if taking nitroglycerin)
Under a doctor’s supervision, supplementing with NAC may improve the effects of nitroglycerin.

(N-acetyl cysteine) may improve the effects of nitroglycerin in people with angina. People with unstable angina who took 600 mg of NAC three times daily in combination with a nitroglycerin transdermal (skin) patch for four months had significantly lower rates of subsequent heart attacks than did people who used either therapy alone or placebo.

2 Stars
Autism
Use with a doctor’s supervision
A double-blind study found that supplementing with NAC for 12 weeks improved symptoms of irritability in children with autism.
In a double-blind trial, supplementation with N-acetylcysteine (NAC) for 12 weeks improved symptoms of irritability in children with autism. The amount of NAC used in the study was 900 mg per day for four weeks, then 900 mg twice a day for four weeks, then 900 mg three times per day for four weeks. Another double-blind study found an improvement in irritability using smaller amounts of NAC: 600 mg per day for children weighing less than 44 pounds and 900 mg per day for children weighing 44 pounds or more. However, in a third double-blind trial, NAC in an average amount of 56 mg per 2.2 pounds of body weight per day for 12 weeks was of no benefit in autistic children. Because the amounts of NAC used in these studies are relatively large and the long-term safety of this treatment has not been examined, NAC treatment of autistic children should be monitored by a doctor.
2 Stars
Gastritis
1 gram daily
In one study, people with atrophic gastritis given NAC saw increased healing.

Various amino acids have shown promise for people with gastritis. In a double-blind trial, taking 200 mg of cysteine four times daily provided significant benefit for people with bleeding gastritis caused by NSAIDs (such as aspirin). Cysteine is a sulfur-containing amino acid that stimulates healing of gastritis. In a preliminary trial, 1–4 grams per day of (N-acetyl cysteine) given to people with atrophic gastritis for four weeks appeared to increase healing.Glutamine, another amino acid is a main energy source for cells in the stomach and supplementation may increase blood flow to this region. Patients in surgical intensive care units often develop gastrointestinal problems related to a glutamine deficiency. When burn victims were supplemented with glutamine, they did not develop stress ulcers, even after several operations. Nevertheless, it remains unclear to what extent glutamine supplementation might prevent or help existing gastritis. Preliminary evidence suggests the amino acid arginine may both protect the stomach and increase its blood flow, but research has yet to investigate the effects of arginine supplementation in people with gastritis.

2 Stars
Heart Attack
Consult a qualified healthcare practitioner
In one study, NAC injections decreased the amount of tissue damage in people who had suffered a heart attack.
In one study, intravenous injections of NAC (N-acetyl cysteine) decreased the amount of tissue damage in people who had suffered a heart attack.[REF] Whether oral NAC would have the same effect is unknown.
2 Stars
HIV and AIDS Support
800 mg daily
Supplementing with NAC may slow the decline in immune function.

The amino acid (N-acetyl cysteine) has been shown to inhibit the replication of HIV in test tube studies. In a double-blind trial, supplementing with 800 mg per day of NAC slowed the rate of decline in immune function in people with HIV infection. NAC also promotes the synthesis of glutathione, a naturally-occurring antioxidant that is believed to be protective in people with HIV infection and AIDS.

2 Stars
Smoking Cessation
Refer to label instructions
N-Acetylcysteine (NAC) has been found to be beneficial in the treatment of various types of addiction, including tobacco addiction in one double-blind trial.
N-Acetylcysteine (NAC) has been found to be beneficial in the treatment of various types of addiction. In a double-blind trial, 34 people addicted to tobacco received 1,500 mg of NAC or a placebo twice a day for 12 weeks, in addition to behavioral therapy. The proportion of people who quit smoking was significantly higher in the NAC group than in the placebo group (47% vs. 21%).
2 Stars
Unverricht-Lundborg Disease
Requires a doctor's supervision
1 Star
Bipolar Disorder
Refer to label instructions
In a preliminary trial, depression in patients with bipolar disorder significantly improved after NAC treatment.
In a preliminary trial, depression in patients with bipolar disorder significantly improved after N-acetyl cysteine treatment (1,000 mg twice a day for eight weeks). Double-blind trials are needed to confirm this benefit.
1 Star
Lupus
600 mg three times per day
In a case report, a woman with kidney disease due to SLE (lupus nephritis) may have had an improvement in her kidney function due to treatment with N-acetylcysteine (NAC).
In a case report, a woman with kidney disease due to SLE (lupus nephritis) had an improvement in her kidney function and was able to taper off of her steroid medicine after starting treatment with N-acetylcysteine (NAC) in the amount of 600 mg 3 times per day. She continued NAC, and after a total of 13 months her disease was considered inactive.
1 Star
Neuropathy
1,200 mg daily
A small body of evidence suggests N-acetyl cysteine may help prevent neuropathy.
N-acetyl cysteine (NAC) is a precursor to one of the body’s most important antioxidants, glutathione. A small body of evidence suggests NAC may be helpful in preventing peripheral neuropathy. In a placebo-controlled trial with 90 participants with type 2 diabetes and neuropathy, adding 600 mg of NAC twice daily to usual pain medication for eight weeks led to reduced pain scores and better sleep. Another placebo-controlled trial that included 14 colon cancer patients found 1,200 mg daily of NAC reduced the incidence of oxiplatin-induced neuropathy after 12 chemotherapy cycles.

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