N-Acetylcysteine may help protect the liver from non-alcoholic fatty liver disease, alcohol damage, and other conditions.
N-acetylcysteine (NAC) is a natural compound with multiple health applications. NAC has been suggested to support liver health through:
- Antioxidant activity. NAC helps produce the antioxidant glutathione, which plays a key role in protecting the liver from damage.
N-Acetylcysteine (NAC) is a natural compound that turns into the amino acid L-cysteine when ingested. In turn, L-cysteine helps produce glutathione (GSH) – one of the body’s main antioxidants.
Clinicians often use NAC for conditions where the body’s GSH levels are low or depleted, such as immune system concerns, lung, heart, and liver conditions. For example, NAC is extensively used to protect the liver from damage caused by acetaminophen (Tylenol) overdose, and is utilized for liver transplants. 1
As a dietary supplement, NAC is used to support the immune system, clear mucus, and help with OCD, anxiety, Alzheimer’s and other cognitive issues. Some people also take it before alcohol consumption to help protect the liver, and for other liver concerns such as non-alcoholic fatty liver and hepatitis C.
How N-Acetylcysteine Might Help With Liver Health
Oxidative stress caused by free radicals is known to play a critical role in virtually all liver conditions and injuries.2 N-Acetylcysteine is a precursor to glutathione (GSH) – one of the body’s main antioxidants – which is particularly important in protecting the liver. NAC helps maintain optimal GSH levels in liver cells. 3
N-Acetylcysteine Uses & Benefits for Liver Health
Some people take N-acetylcysteine to help with chronic liver conditions such as non-alcoholic fatty liver and hepatitis C. In addition to this, NAC can also be taken prior to alcohol consumption to help protect the liver from damage. However, it should be noted that taking NAC during or after drinking can actually have the opposite effect, worsening the effects of alcohol.
There are several human studies highlighting the liver benefits of NAC, particularly in the context of non-alcoholic fatty liver. In addition, animal studies support NAC’s ability to protect the liver from alcohol and other toxins, as well as chronic liver conditions. Taken together, this evidence supports the use of NAC for liver health.
Animal and isolated cell culture studies of NAC report multiple liver-protective effects. Specific findings indicate that N-acetylcysteine:
- Slows the progression of nonalcoholic steatohepatitis (NASH) in rats 5
- Protects against liver damage and injury in rats 6 7
- Protects the liver against alcohol damage 8
Human studies of N-acetylcysteine suggest that it protects against non-alcoholic fatty liver disease and other types of liver damage such as acute liver failure.
This study examined the effects of N-acetylcysteine (NAC) on non-alcoholic fatty liver disease. A total of 30 people with non-alcoholic fatty liver were given vitamin C (1000 mg) or N-acetylcysteine (600 mg) twice daily for 3 months. Only the NAC group experienced a significant reduction in alanine aminotransfrase (ALT) enzyme levels, indicating improved liver function.
- The researchers concluded that “N-acetylcysteine can improve liver function in patients with non-alcoholic fatty liver disease.” 9
This randomized study evaluated the effects of N-acetylcysteine (NAC) on non-alcoholic steatohepatitis (NASH). A total of 35 patients were divided into two groups: control (no treatment) or NAC (600 mg) daily for 4 weeks. Although both groups experienced an improvement in ALT levels – an enzyme marker of liver function – only the NAC group had additional decreases of the AST and GGT liver enzymes.
- The researchers concluded that “improvements in biochemical parameters in patients with NASH was not interpreted as the therapeutic effect of the drug.” 10
This study examined the benefits of N-acetylcysteine (NAC) for non-alcoholic steatohepatitis (NASH) in combination with the medication metformin. Twenty participants were given NAC (1200 mg) and metformin (850-1000 mg) daily for 12 months. The combination treatment improved various markers of NASH, including levels of liver enzymes and liver steatosis (fat accumulation) and fibrosis.
- The researchers concluded that “…NAC in combination with MTF appears to ameliorate several aspects of NASH, including fibrosis.” 11
This study examined the benefits of N-acetylcysteine (NAC) in protecting against acute liver failure. Seven patients with acute liver failure were given NAC, with 4 experiencing full recovery.
- The researchers concluded that “…N-acetylcysteine administration should be considered in all patients with acute liver failure.” 12
Dosage for Liver Health
- Most successful studies use 600 – 1200 mg dosages of N-acetylcysteine
- Standalone NAC supplements typically provide 1200 mg dosages
- N-acetylcysteine is typically sold as a powder, by itself or in capsules.
Supplements in Review Recommendation
- N-Acetylcysteine, 1200 mg for liver health.
We recommend giving NAC a try for liver health. Although more clinical research is needed, current evidence suggests that N-acetylcysteine may help keep liver enzymes in healthy levels and protect the liver from alcohol and chronic disorders.
The most common dosage is 1200 mg. Most human studies – and supplements – use 1200 mg dosages of N-acetylcysteine.
- Smilkstein MJ et al. Efficacy of oral N-acetylcysteine in the treatment of acetaminophen overdose. Analysis of the national multicenter study (1976 to 1985). N Engl J Med. 1988 Dec 15;319(24):1557-62. ↩
- Halina Cichoż-Lach and Agata Michalak. Oxidative stress as a crucial factor in liver diseases. World J Gastroenterol. 2014 Jul 7; 20(25): 8082–8091. ↩
- Duangporn Thong-Ngam et al. N-acetylcysteine attenuates oxidative stress and liver pathology in rats with non-alcoholic steatohepatitis. World J Gastroenterol. 2007 Oct 14; 13(38): 5127–5132. ↩
- JohnSlattery et al. Clinical trials of N-acetylcysteine in psychiatry and neurology: A systematic review. Elsevier Neuroscience & Biobehavioral Reviews Volume 55, August 2015, Pages 294-321. ↩
- Baumgardner JN et al. N-acetylcysteine attenuates progression of liver pathology in a rat model of nonalcoholic steatohepatitis. J Nutr. 2008 Oct;138(10):1872-9. ↩
- Cetinkaya A et al. N-acetylcysteine ameliorates methotrexate-induced oxidative liver damage in rats. Med Sci Monit. 2006 Aug;12(8):BR274-8. ↩
- Norifumi Kawada et al. Effect of antioxidants, resveratrol, quercetin, and N‐acetylcysteine, on the functions of cultured rat hepatic stellate cells and kupffer cells. Hepatology. 1998 May;27(5):1265-74. ↩
- D. S. JayaJ. AugustineV. P. Menon. Protective role of N-acetylcysteine against alcohol and paracetamol induced toxicity. Indian Journal of Clinical BiochemistryDecember 1994, Volume 9, Issue 2, pp 64–71. ↩
- Manouchehr Khoshbaten et al. N-Acetylcysteine Improves Liver Function in Patients with Non-Alcoholic Fatty Liver Disease. Hepat Mon. 2010 Winter; 10(1): 12–16. ↩
- Pamuk GE and Sonsuz A. N-acetylcysteine in the treatment of non-alcoholic steatohepatitis. J Gastroenterol Hepatol. 2003 Oct;18(10):1220-1. ↩
- de Oliveira CP et al. Combination of N-acetylcysteine and metformin improves histological steatosis and fibrosis in patients with non-alcoholic steatohepatitis. Hepatol Res. 2008;38(2):159-65. ↩
- Ben-Ari Z et al. N-acetylcysteine in acute hepatic failure (non-paracetamol-induced). Hepatogastroenterology. 2000 May-Jun;47(33):786-9. ↩