N-acetylcysteine, known by its more common abbreviation NAC, is a supplement that can be used for everything from treating upper respiratory infections to improving mental health issues to protecting your lungs to helping you kick addictions.
It was originally developed as a medical intervention to treat acetaminophen overdose, but has found far-reaching application as a treatment for a great number of health problems, and is an area of active research.
Need a NAC supplement that’s got the right dosage and the right ingredients? We’ve got you covered. Our researchers have ranked the ten best NAC supplements on the market.
1. NOW NAC
NOW NAC provides 600 mg of NAC, alongside two critical trace elements for proper hormone and protein synthesis, molybdenum and selenium.
The supplement is encapsulated in a caplet made of vegetable cellulose and doesn’t include any unnecessary binders or fillers, making it a great choice.
2. Life Extension N-Acetylcysteine
Following the standard clinical trial protocol, Life Extension makes 600 mg capsules of NAC. The supplement design is very clean, with just a few ingredients to hold the vegetarian capsule together, and with the quality that Life Extension is known for, this NAC supplement is an excellent choice.
3. Integrative Therapeutics NAC
Integrative Therapeutics offers a high-grade NAC supplement that’s super-minimal in its design. In total, it’s got only three ingredients: N-acetylcysteine, gelatine, and rice flour.
If you don’t want any unnecessary ingredients in your NAC supplement, this is definitely the way to go. The only drawback? The gelatin capsule isn’t vegetarian-friendly.
4. Jarrow Formulas NAC Sustain
Jarrow Formulas delivers a standard 600 mg dose of NAC, but what makes this supplement unique is its capsule. It uses a few binders and excipients to bind part (but not all) of the NAC in a slower-releasing form.
The effect is that some of the NAC gets released immediately, while the rest of it diffuses more slowly into your bloodstream.
This is hypothetically an advantageous way to deliver NAC, though most scientific research does not use this kind of formulation. Purists might not like the need for additional ingredients to achieve this slow/quick release effect, but it could be a good choice if you want sustained levels of NAC throughout the day.
5. Nutricost NAC
Nutricost’s NAC supplement has just a couple of extra additives, but they’ll only be an issue for the strictest of supplement purists.
The main advantage to this NAC supplement is that the bottle provides 180 capsules, a lot more than some other brands out there, so if you’re in it for the long haul, this is a good choice.
6. Solgar NAC
Solgar is a reliable source of fairly straightforward supplements, and that’s certainly the case with their NAC supplement.
It delivers 600 mg of N-acetylcysteine in a vegetable-based capsule with a couple of binders, so it’s a pretty safe bet if you are looking for something mainstream.
7. Pure Encapsulations NAC
Pure Encapsulations makes a 600 mg NAC supplement contained in a vegetarian-friendly cellulose capsule. Instead of inert binders like rice flour, this supplement uses ascorbyl palmitate (a vitamin C derivative) as both a binder and preservative.
Some may not like this slightly more exotic ingredient in their supplement, but aside from this, the design is pretty clean.
8. Source Naturals N-Acetylcysteine
Source Naturals makes a high-dose NAC supplement with 1000 mg of NAC per tablet. Unlike most of its competitors, it is pressed into a slow-dissolving tablet instead of a fast-dissolving capsule.
This adds a lot of binders that need to be included to hold the materials together, but it is likely the most advantageous way to deliver a higher dose of NAC. It’s a solid go-to if you need the high dosage, but others are better when it comes to the standard 600 mg dosage.
9. Swanson NAC
Swanson NAC has the standard 600 mg dosage, though it also has a couple of extra ingredients and isn’t vegan-friendly due to its gelatin capsule. Aside from that, it’s a solid product, but doesn’t stand out from the crowd.
10. Thorne Research NAC
The dosage in Thorne Research’s NAC supplement is somewhat lower than the usual, at 500 mg. It’s also got a few binders like silicon dioxide that some strict supplement purists try to avoid.
In spite of these flaws, if you are looking for a lower dosage, it would be a good choice.
Who should buy NAC?
The benefits of NAC span both physical and mental performance. NAC’s primary application is boosting your antioxidant levels through its ability to upregulate glutathione production, but despite this seemingly narrow application, NAC has a wide range of potential health applications.
This apparent paradox can be resolved by realizing how many aspects of health are related to inflammation. NAC has been around for a long time, but researchers are taking a second look at its ability to help people quit addictions, treat mental health disorders, improve cognitive function, and even increase endurance performance.
NAC is also great for boosting your immune system if you have an infection, particularly infections that affect your respiratory tract like the common cold or the flu.
In sum, NAC is a good supplement if you think your antioxidant capabilities aren’t what they should be, or if your immune system needs a jump-start.
In addition, NAC might be useful for people trying to get a handle on mental and behavioral problems, like depression, anxiety, or addiction, in addition to counseling and pharmacological help as needed. NAC exerts powerful beneficial effects on your brain, by protecting cells against oxidative damage, reducing programmed cell death, and shifting the balance of neurotransmitters in your brain.
All of these effects contribute to the rapidly growing body of research on NAC for mental health and wellness.
How we ranked
With our NAC rankings, we were mindful of the extremely broad range of applications for NAC supplements, from endurance exercise performance to treating addiction and mental health problems.
As such, we wanted to make sure the products on our list were pure, effective, and well-suited for this wide range of potential uses. Starting from all of the NAC-containing products from well-regarded manufacturers, we narrowed the field to NAC supplements whose sole active ingredient was N-acetylcysteine.
Our only exception to this was products which included trace amounts of minerals that are important in the enzymatic processes surrounding NAC’s biological pathways, such as molybdenum and selenium.
After surveying the scientific literature on effective dosages for NAC for its wide-ranging applications, we narrowed our field further so it contained only NAC supplements that contained between 500 and 1000 mg of NAC per capsule.
Most applications call for 500 to 600 mg, taken twice daily, but a few studies include higher doses—we made sure we kept at least one high-dose NAC option on the list for exactly this reason.
From here, we focused on purity and clean supplement design. The best performing NAC supplements were those that used very little in the way of binders, fillers, and extra or unnecessary ingredients.
Supplements that were bloated with extras were dropped. Finally, we took note of any distinctive supplement design features, such as the extended-release formulation used by Jarrow Formulas.
Some users who want to sustain high levels of NAC throughout the day might find a supplement like this useful, while others may want to hew as close to the clinical research recommendations as possible.
Fortunately, doing either is an option with our final rankings, which represent the purest and highest-quality NAC supplements on the market right now.
NAC has a broad range of physical and mental health applications. N-acetylcysteine was initially used in hospital settings, but gradually more and more research started to demonstrate that its uses extended into managing, treating, and even preventing a wide range of long-term health problems.
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.
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.
NAC could 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.
NAC is helpful for getting over addictions 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 (3).
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 (4). 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 prescribed either a 1200 mg daily dose of NAC or a placebo to a group of adolescents who were seeking treatment for cannabis addiction (5).
Over the course of eight weeks, the researchers used urine tests to determine whether the subjects were successful in their attempts to quit using cannabis. The results showed that the group that received the NAC supplement was twice as likely to be successful in their attempts to quit compared to the group that received the placebo.
Taking a NAC supplement 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 examined the effects of 1200 mg of NAC daily on biomarkers for DNA damage in cigarette smokers (6).
Over a period of six months, a group of 41 subjects took either a NAC supplement or a placebo, and the researchers tested the subjects for biomarkers of DNA damage—presumed to be linked to the host of negative health effects of smoking. The researchers found consistently lower levels of DNA damage in the smokers who took the NAC supplement compared to placebo.
The subjects were specifically instructed to continue their normal smoking habits, so we can’t tell whether NAC caused any reduction in smoking cravings.
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.
NAC appears to help a wide range of mental health issues. Berk and colleagues highlight a wide-ranging spectrum of research that has demonstrated benefits of using NAC to treat mental disorders, from autism to schizophrenia to Alzheimer’s disease.
How could this supplement be useful in such a wide variety of situations? The authors of the review article suggest it is 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 a number of 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.
NAC can help boost exercise performance and reduce oxidative damage if your antioxidant levels are low. 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.
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.
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 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.
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 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.
Q: What is NAC used for?
A: NAC is one of the most versatile supplements out there, because of its wide range of uses. It’s been used in scientific research to boost aerobic endurance, improve cognitive function, and speed recovery from infections.
But those aren’t even the most interesting applications of NAC—the latest research published in the last few years is examining NAC as a potential treatment for mental health issues ranging from depression and anxiety to addiction and schizophrenia.
Q: Can NAC help anxiety?
A: NAC as a treatment for anxiety has strong empirical backing from animal model studies—research on both fish (9) and mice (10) supports an anxiolytic (anxiety-reducing) effects, and some case studies have explored NAC as a treatment for individuals with serious anxiety problems.
The biological basis of NAC as an anxiety treatment is fairly strong too, based on what’s known about the neurological effects of NAC supplementation. Moreover, secondary analysis on a trial of NAC for treating OCD found that, while NAC didn’t improve OCD symptoms directly, it did reduce feelings of anxiety (11).
While there have not been any large, high-quality randomized controlled trials of NAC for anxiety yet, it appears that the time is ripe for one—within a few years, there is likely to be much more evidence on this front.
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 (12).
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.
Q: Can NAC help depression?
A: NAC has been examined in a number of studies as a possible treatment for depression. A recent review article published in 2016 examined the results of five different clinical studies on NAC for depression (13).
The review, published in the Journal of Clinical Psychiatry by a team of researchers in Australia, pooled the results of the five separate studies together. The results showed that NAC had a significant effect on lessening the severity of depression symptoms and improving quality of life.
This research is still quite new, but applying NAC to depression and other common mental health problems looks to be a potentially promising avenue of treatment.
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: Can NAC help with obsessive compulsive disorder?
A: With the success at treating other mental health issues, like addiction and depression, with NAC, researchers wondered if NAC could also be helpful for obsessive compulsive disorder, or OCD.
OCD is a challenging mental health problem to manage, so a success here would be very valuable. A study published in 2017 tested the effects of NAC versus a placebo on a group of patients with treatment-resistant OCD related behavior (14).
The dose of NAC was quite high, at 3000 mg per day. Despite this, the study did not find any significant differences between the groups in terms of OCD-related behavior.
A secondary analysis did find that NAC helped reduce symptoms of anxiety. The takeaway from this study is that NAC may help with some of the secondary problems associated with OCD, but isn’t likely to help with the primary symptoms.
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 (15).
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: Can NAC benefit your skin?
A: Due to the antioxidant effects of glutathione, which is synthesized directly from NAC, it’s natural to wonder whether NAC supplementation can improve skin function. We see the same effects with other potent antioxidant agents, like astaxanthin or vitamin C.
With NAC, the evidence is more preliminary, but animal models do suggest that NAC can help protect your skin from ultraviolet light. One study in mice was able to show that NAC supplementation significantly delayed the onset of skin tumors after chronic exposure to ultraviolet light (15).
Whether this translates into anti-aging effects in human skin remains to be seen, but this is a good sign.
Q: How long does it take for NAC to work?
A: Experiments on NAC supplementation typically last at least 30 days, and often much longer, so it pays to wait for at least a few weeks before you decide whether NAC supplementation is helping.
As with any supplement that tries to exert changes on your neurochemistry, you should expect the changes to be slow and gradual. If it’s been a few months and you don’t feel like NAC is helping at all, it might be time to try something else, but if you’ve only been taking NAC for a week or two, definitely give it some more time.
NAC shows promise on a number of fronts, from treating and preventing the flu and other viral infections to treating mental disorders and kicking an addiction to cocaine, cannabis, or tobacco.
This simple biological precursor appears to have a wide variety of benefits thanks to its anti-inflammatory and antioxidant powers. In addition, it has potent beneficial effects on neurological function too, which probably accounts for its broad uses for mental health as well.
The usual dosage for achieving these benefits is 600 mg taken in capsule form twice per day (morning and evening). At this dosage level, side effect are relatively rare, but can include flushing, a rash, nausea, and other gastrointestinal issues.
People who take vasodilators shouldn’t take NAC without talking to their doctor first, but aside from this, NAC appears to be fairly well-tolerated.
For BodyNutrition‘s #1 NAC recommendation, click here.