Diet & Fitness

NAC (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.¹ Oral NAC, 200 mg taken three times per day, is also effective and improved symptoms in people with bronchitis in double-blind research.^2,3 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.^4,5 However, NAC was ineffective in one study.⁶ Results may take six months. NAC does not appear to be effective for people with COPD who are taking inhaled steroid medications.⁷

 

NAC (N-acetyl cysteine) may improve the effects of nitroglycerin in people with angina.⁸ 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.⁹

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.

 

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).¹⁰ Cysteine is a sulfur-containing amino acid that stimulates healing of gastritis. In a preliminary trial, 1–4 grams per day of NAC (N-acetyl cysteine) given to people with atrophic gastritis for four weeks appeared to increase healing.¹¹Glutamine, another amino acid is a main energy source for cells in the stomach and supplementation may increase blood flow to this region.¹² Patients in surgical intensive care units often develop gastrointestinal problems related to a glutamine deficiency.¹³ When burn victims were supplemented with glutamine, they did not develop stress ulcers, even after several operations.¹⁴ 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,¹⁵ but research has yet to investigate the effects of arginine supplementation in people with gastritis.

 

A review of 39 clinical trials of NAC (N-acetyl cysteine) found that 400 to 600 mg per day was a safe and effective treatment for chronic bronchitis.¹⁶ 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.¹⁷ 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.¹⁸ In another double-blind study, people with chronic bronchitis who took NAC showed an improved ability to expectorate and a reduction in cough severity.¹⁹ These benefits may result from NAC’s capacity to reduce the viscosity (thickness) of sputum.²⁰

 

The amino acid NAC (N-acetyl cysteine) has been shown to inhibit the replication of HIV in test tube studies.²¹ 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.²²

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.²³

In a double-blind trial, supplementation with N-acetylcysteine (NAC) for 12 weeks improved symptoms of irritability in children with autism.²⁴ 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.²⁵ 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.²⁶ 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.

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).²⁷ Double-blind trials are needed to confirm this benefit.