NAC is a supplement that increases levels of a potent antioxidant called glutathione. It’s used for boosting immune function, improving mental wellbeing, and fighting inflammation in the body.
Because of its potential for systemic effects on your body, NAC sees a broad range of uses among enthusiasts for long-term health supplementation.
From anti-aging stacks to supplementation strategies for improving mental health, NAC is a mainstay for many different supplement plans.
Want to incorporate NAC into your own health regimen? Here’s everything our research team found when looking into the evidence behind the benefits of NAC.
1. NAC works by boosting glutathione levels
NAC supports lung function, immune function, and mental health, likely by increasing your body’s levels of glutathione, a strong antioxidant that your body produces using NAC as a precursor.
The antioxidant strength of glutathione is likely one major reason for the wide ranges of uses for NAC.
2. NAC can reduce the severity of viral infections like the flu
Research on NAC was initially grounded in its use to treat acute lung injuries by leveraging its antioxidant properties, but researchers soon expanded the range of their research to look at how NAC might improve other lung-related problems, such as infection by the flu virus (which thrives in the lungs).
Researchers in Italy published the results of an experiment in the International Journal of Immunopathology and Pharmacology in 2009 that examined how flu virus affected a mouse model (1).
The researchers exposed two groups of mice to flu virus, and one of them was also regularly supplemented with NAC. Three days later, the mice that had received NAC supplement fared far better; significantly fewer had succumbed to the flu virus.
3. NAC could help prevent infections
A clinical trial in elderly patients used NAC to attempt to prevent infection with the flu virus, and found good results.
According to a review by Paul J Millea in the journal Complementary and Alternative Medicine, the researchers found that, compared to a placebo, only 29% of the patients receiving NAC got infected with the flu during the flu season, compared to 51% of those receiving the placebo (2).
Blood testing revealed that a similar proportion of both groups were exposed to the flu virus, indicating that many of the patients who received NAC got over the virus and developed immunity without any symptoms. The same benefits may extend to other respiratory infections, such as the common cold.
4. NAC can reduce addiction cravings for cocaine and cannabis
One of the first areas of promising research that Berk and his colleagues highlight is a body of work that has established that NAC can be very useful for fighting addiction cravings.
One study published in the American Journal of Psychiatry studied the effects of NAC or a placebo on cocaine-addicted patients during a three day hospital stay (3). Compared to the placebo, NAC significantly reduced cocaine cravings in the patients.
Similar results have been found in the treatment of cannabis cravings. Another study published in the American Journal of Psychiatry showed that a 1200 mg daily dose of NAC reduced cannabis cravings, improving the odds of quitting two-fold (4).
5. NAC can reduce lung damage from smoking
Only one study directly looked at using NAC to treat cigarette addiction, but the already-small trial was hampered by a number of confounding variables. As a result, whether NAC can directly assist with smoking cessation remains unclear.
However, NAC does appear to be able to reduce the damage that your lungs sustain when you are smoking, so at the very least it could be an adjunctive treatment for smokers who are struggling to quit. A study published by researchers in the Netherlands found reduced biomarkers of DNA damage thanks to a 1200 mg NAC supplement in cigarette smokers (5).
The best approach here is to use NAC while you are trying to quit. If you are slowly reducing your cigarette usage, it will help protect your lungs from further damage, and, though the data aren’t in yet, it may help reduce your cravings as well, based on research on other addiction behaviors.
6. NAC could combat addiction and mental health problems
The benefits of NAC extend beyond the purely physiological.
According to a review article by Michael Berk and other researchers at Deakin University School of Medicine in Australia, NAC targets a number of neurotransmitters linked to better mental well-being and has been studied intensively, with promising results for a range of mental health problems from autism to schizophrenia to Alzheimer’s disease (6).
How could this supplement be useful in such a wide variety of situations? It’s either due to the broad-spectrum anti-inflammatory and antioxidant effects of glutathione, which is synthesized from NAC, or due to a direct effect of NAC on one of several neurotransmitters.
Though there is still quite a lot of research to be done on this front, NAC, a simple and inexpensive supplement, shows tremendous promise when it comes to treating mental disorders.
7. NAC can boost exercise performance and reduce oxidative damage
Some emerging research has uncovered evidence for a strong connection between NAC and the powerful antioxidant glutathione.
A study published in 2018 in the journal Free Radical Biology and Medicine looked at the effects of a NAC supplement on a group of 100 people, who were initially screened for low, medium, and high levels of glutathione, an important antioxidant (7).
NAC happens to be a precursor to glutathione, which is why the researchers screened for this particular biomarker. The researchers found that the 1200 mg (600 mg two times per day) supplementation routine, which lasted for a full month, was effective at boosting athletic performance and increasing antioxidant levels, but only in the group of subjects that had low levels of glutathione.
This strongly suggests that the mechanism of action of NAC is to boost your body’s antioxidant levels, probably by increasing glutathione levels.
So, if you know your body’s antioxidant levels are low, there’s a better chance that NAC will help you improve your performance and health.
NAC side effects
NAC can cause nausea, skin flushing, rashes, and GI problems. According to a review article by Dr. Paul Millea, side effects are rare at the usual dosing level of 600 mg twice daily, but side effects can include nausea, skin flushing, developing a rash, constipation, diarrhea, or other gastrointestinal problems (8).
NAC’s side effects mostly show up at higher doses. Since it does have some wide-reaching effects on your body, NAC does have a number of negative side effects. When used in medical settings, side effects can be fairly serious, but this is at a much higher dose than when taken as a supplement.
NAC can interact with vasodilating drugs. NAC can also interact with drugs that act as vasodilators, such as nitrates. People who use these kinds of medications shouldn’t take NAC without talking to their doctor first.
Almost all studies use a 600 mg dosage. The dosing protocol used nearly universally in clinical trials of NAC is 600 mg, taken in capsule form twice per day (morning and evening).
The lack of variety in clinical trials may be a result of the outgrowth of NAC research from its use in hospital setting, where dosages have been standardized.
A few studies have tested a 1200 mg dosage. A small number of studies have tested 1200 mg twice per day, but adverse effects are more common at this higher dosage. Unless you’ve got a good reason not to, 600 mg twice per day is what you should stick with.
NAC benefits FAQ
Q: What does NAC do for the brain?
A: NAC’s ability to alter antioxidant levels in your body has a direct link to its ability to alter your brain chemistry in beneficial ways. A review study on the psychological and neurological applications of NAC notes that NAC can improve mitochondrial function in your brain, reduce cell death, and reduce inflammation in your brain (9).
All of these effects have benefits with regards to cognitive function and mental health. In keeping with other research on the biological and nutritional basis of mental health, these findings suggest a direct link between the health of your brain and the biochemical balance of inflammation in the rest of your body.
Q: Does NAC have negative effects?
A: NAC has been associated with some side effects in some of the clinical trials that have been conducted, but these tend to be transient and mild, like stomach discomfort.
At a first glance, these side effects also tend to appear in the studies which use larger doses of NAC (2-3 grams per day). The primary negative effects of NAC are really only of concern to people who take vasodilators, like nitrates for chest pain.
That’s because of potential drug/supplement interactions, which are something you should talk to your doctor about before using NAC if you take this category of medication.
Q: What foods are rich in NAC?
A: While NAC itself can only be garnered in significant amounts in supplement form, you can increase your body’s levels of NAC by increasing your intake of your favorite healthy protein-rich foods, like eggs, dairy, poultry, nuts and seeds, and legumes.
In addition, increasing your consumption of sulfur-containing vegetables like kale, broccoli, and cauliflower can help boost your body’s level of cysteine, a compound that’s closely related to NAC.
However, unlike some other supplements like fish oil, it’s not really possible to get a comparable level of NAC intake from your diet alone, versus what you’d be able to get in a standard NAC supplement.
Q: Is NAC safe to take daily?
A: NAC has been used in a wide range of scientific studies, at dose of up to three grams per day, and side effects are rare and minor.
The only people who should definitely hold off on taking NAC would be people who take nitrates or other vasodilating medication, which is usually prescribed for heart disease.
NAC’s safety is firm enough even for clinical research on using NAC in people with fairly serious medical conditions, such as clinical depression and treatment-resistant anxiety.
Q: Can NAC cause liver damage?
A: NAC is actually used to prevent or reduce liver damage in patients, so the suggestion that NAC could harm your liver doesn’t seem to hold. NAC is actually a first-line treatment for people who have overdosed on acetaminophen, and has also been shown to improve liver function among people with non-alcoholic fatty liver disease (10).
While NAC has not been shown to help liver function in healthy people who do not have liver disease, at least you can be confident that NAC is not going to be harmful to your liver.
Related: Our best NAC picks
NAC is great if you are looking for a potent antioxidant to add to your supplementation regimen. It’s got an impressive range of beneficial uses, spanning both physical and mental health.
It’s an excellent pick if you are looking for a supplement that could help boost your mood or kick an addiction, and it’s also great for boosting immune system function and fighting systemic inflammation in the body. When it comes to a versatile antioxidant supplement, NAC is hard to beat.