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NAC N-acetyl cysteine

In the family of sulphur-containing amino acids derived from plants of the Allium family, N-acetyl cysteine (NAC) is a powerful antioxidant and anti-inflammatory nutrient that supports the health of the immune system, liver, lungs, reproductive, gastrointestinal and neurological health. NAC is the chemical precursor to a very important antioxidant: glutathione.

Healing actions


Studies have demonstrated the anti-inflammatory activity of NAC. Reducing the inflammation cascades triggered by nuclear factor NF-кB and tumour necrosis factor TNF-α, it reduces crucial proinflammatory cytokines such as interleukins IL-6 and IL-1β, the cytokines involved in inflammatory responses, including septic shock.

Antioxidant and chemical detoxification

NAC neutralises a range of free radicals directly as well as by forming glutathione. It neutralises lipid peroxidation, the mechanism for cell injury in acute or chronic pesticide poisoning, thus having the potential to reduce toxicity induced by pesticides.

NAC helps support and heal organ failure of liver and kidneys due to cell damage by oxidative stress induced by organophosphates or carbamate pesticide injury.

Respiratory and antiviral

The clinical use of NAC was first reported in the 1960s when, due to its powerful mucolytic (ie mucus-dissolving) activity, it effectively treated patients with cystic fibrosis.

This mucolytic activity makes NAC effective in early stages of acute lung infections where it reduces respiratory mucus and inflammation by increasing glutathione levels, as well as being used successfully long term to relieve the symptoms of chronic bronchitis.

NAC has potent antiviral effects against HIV and hepatitis C and a range of respiratory viruses, including against COVID-19. In one recent study on 19,208 hospitalised patients with COVID, 2071 were treated with high-dose NAC, particularly those with a higher baseline risk, that is older patients, those with increased comorbidities etc. While their medical treatments remained the same, those taking NAC had significantly lower mortality rates than the other patients.


NAC is used in patients with chronic pulmonary diseases, including tuberculosis. Both in vitro and mouse studies showed that NAC had potent antimycobacterial effects and could limit Mycobacterium tuberculosis infections both through its direct antimicrobial activity and by suppressing oxidation caused by the infection.


Many of today’s neurodegenerative diseases are thought to have causal factors in environmental chemicals generating inflammation and oxidation. NAC strengthens the blood–brain barrier against inflammatory and oxidative compounds that contribute to amyloid beta protein accumulating in the brain, thereby reducing the risk for Alzheimer’s disease. NAC strengthens the blood–brain barrier but also crosses it, thereby reducing inflammation locally as well.

Research has shown a role for NAC in improving the symptoms of depression, anxiety, PTSD, schizophrenia, bipolar disorder, Parkinson’s disease, OCD in children and in adults and as an adjunctive treatment to reduce irritability in autism.


Research on a group of women with PCOS (polycystic ovary syndrome) showed that treatment by it increased glutathione levels, vitamin A, beta-carotene, vitamin E and total antioxidant
status. In conjunction, lipid peroxidation, luteinising hormone, testosterone, insulin, IL-1 and homocysteine were decreased. These results showed the positive impact NAC had on reducing oxidation and therefore symptoms in PCOS.

Taking NAC

Doses prescribed are between 500 and 1800mg per day depending on the type of health problem and whether it is acute or chronic. It is better taken with vitamin C to prevent kidney stones, particularly if taking it long term.

Drug interactions

A common drug prescribed for autoimmune rheumatoid arthritis and psoriasis has potential toxicity to the liver, lungs and kidneys. Research has indicated that it may help protect these organs during administration.

Cautions and contraindications

N-acetyl cysteine is considered a well-tolerated and safe medication that has been used worldwide for several decades with few recorded adverse side effects. Rarely, high doses may trigger digestive symptoms in those sensitive to sulphur.

Article featured in WellBeing 208

Dr Karen Bridgman

Dr Karen Bridgman

Karen Bridgman is a holistic practitioner at Lotus Health and Lotus Dental in Neutral Bay.

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