NAC and Glutathione Explained Simply

1. What Is NAC and Glutathione?

N-acetylcysteine, or NAC for short, is a sulfur-containing substance. It is a precursor of cysteine, a building block for proteins. Glutathione is a small protein made of three building blocks: glutamate, cysteine, and glycine. The body's cells produce this protein themselves. In medicine, NAC helps to loosen mucus. It is also used as an antidote when someone has taken too much paracetamol. Glutathione is mostly sold as a dietary supplement.

2. Where Is It Found, and What Is It Made From?

Glutathione is present in almost all cells of the body. It is especially abundant in the liver. NAC and glutathione are available as capsules, tablets, effervescent powder, and drinks. Some forms are nebulized or administered through a vein. NAC is produced artificially. Glutathione is also produced artificially or obtained with the help of microorganisms.

3. What Does NAC and Glutathione Do? What Research Shows

Oxidative Stress and Antioxidant Status

In harmful stress in the body, glutathione in the blood rose more strongly with NAC than in the comparison group in several good studies 2641. Other good studies found fewer breakdown products of damaged fats 303146 and a better defense against harmful stress in the blood 304152. However, some studies found no difference from the comparison group in glutathione or in the fat breakdown products 34353646. Most measurements are only blood or cell values and not a real improvement in disease.

Mental Health Conditions

In depression, a summary of several studies showed a small advantage over a sham medication 3. In delusions and thought disorders, another summary found no difference 4. In obsessive-compulsive disorder, an advantage appeared only with a treatment duration of five to eight weeks 10. In pathological hair pulling, NAC is considered well supported according to a summary of many studies 12. In stress disorders after terrible experiences, another summary found no difference 5. Almost always, NAC was given to swallow in addition to the usual treatment.

Addiction and Substance Use

For smoking cessation, NAC helped better than a sham medication 33. In adolescents, the general craving for alcohol was lower than under a sham medication 48. Compared with the medication fluoxetine, NAC lowered craving more strongly 29. In a small study, cocaine-dependent individuals under NAC sought further drugs less after a cocaine administration 50. For abstinence, mostly no difference from the sham medication was found 222328. One summary of many studies found less craving for the drug 13, another found no difference for alcohol craving 5. Almost always, NAC was given to swallow in addition to counseling or usual treatment.

Respiratory Tract and Lungs

In tuberculosis, lung function recovered somewhat better under NAC than with the usual treatment alone 26. In enlarged bronchi, NAC improved lung function and social well-being compared with a sham medication 49. In COVID-19, quality of life improved faster under NAC than under a sham medication 37. In another study, fewer affected individuals had to be hospitalized than with the usual treatment 1953. An NAC spray for inhalation lowered mortality in an open-label study 18. In the lung disease COPD, no difference was found for disease exacerbations and lung function 15, and in acute lung failure none for mortality 6. In lung scarring, NAC in addition to another medication brought no confirmed advantage 7.

Liver

Several studies found better liver values with NAC than in the comparison group 314047. In liver transplantations, NAC improved a liver value only when the donor organ had been stored cold for a long time; survival did not differ 20. Other studies found no difference from the comparison group in liver values 3436444551. A summary after liver operations found only a lower lactate value, but no difference in the course of the disease 8. The overall strength of evidence is low, the studies are small and very different.

Other Investigations

Summaries of several studies found lower mortality in COVID-19 2 and in heart procedures, there also less often kidney damage from contrast agents 1. In nerve damage from chemotherapy or diabetes, fewer symptoms appeared than in the comparison group 3932. In some poisonings, no difference in mortality appeared 303843. The strength of evidence is high, but the findings vary widely.

4. How Was NAC and Glutathione Taken in the Studies?

In the studies, NAC was swallowed, inhaled, given through a vein, or applied to the skin. Glutathione was swallowed, given in a special fat coating, or administered through a vein. Swallowing, inhalation, and administration through a vein were assessed separately. With ready-made mixtures with other active substances, it cannot be said which substance had an effect.

5. Is NAC and Glutathione Safe? Side Effects in the Studies

NAC was mostly well tolerated. Adverse effects occurred no more often than with a sham medication 1013232527. In individual studies, gastrointestinal complaints were more common than with the sham medication 2224. With administration through a vein, more allergy-like reactions were reported 42. Many findings concern only laboratory values and not a real improvement in disease. The studies are mostly small and short.

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