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N-Acetyl-L-Cysteine Supports Detoxification, Skin Health, Immune Function & More*

Kirsten Nunez, M.S.
Author: Expert reviewer:
June 24, 2022
Kirsten Nunez, M.S.
Contributing writer
By Kirsten Nunez, M.S.
Contributing writer
Kirsten Nunez is a health and lifestyle journalist based in Beacon, New York. She has a Master of Science in Nutrition from Texas Woman's University and Bachelor of Science in Dietetics from SUNY Oneonta.
Ashley Jordan Ferira, Ph.D., RDN
Expert review by
Ashley Jordan Ferira, Ph.D., RDN
mbg Vice President of Scientific Affairs
Ashley Jordan Ferira, Ph.D., RDN is Vice President of Scientific Affairs at mindbodygreen. She received her bachelor's degree in Biological Basis of Behavior from the University of Pennsylvania and Ph.D. in Foods and Nutrition from the University of Georgia.

In recent years, the term "detox" has become synonymous with "cleanse"—i.e., something you do occasionally and temporarily. But here's the thing: Detoxification simply doesn't work that way. 

Thanks to your body's hardworking organs and complex antioxidant networks, detoxification is a natural, built-in process that takes place all day, every day—no special "detox diets" necessary.

That said, if you want to support and optimize your body's intrinsic cleanup crew, it's helpful to focus on your daily nutrition choices. This includes what you eat and drink, of course, as well as your personalized supplement lineup. 

For example, mbg's daily detox+ is led by glutathione (a master antioxidant in the realm of detox support) and also contains N-acetyl-L-cysteine—a vital player in the detoxification process that replenishes antioxidants in the body to promote healthy redox balance.*

As a powerhouse antioxidant and critical building block precursor, N-acetyl-L-cysteine and its health benefits are worth calling out. Ahead, learn how the molecule works and why it can help leverage your body's full detoxification potential.*

What is N-acetyl-L-cysteine?

N-acetyl-L-cysteine (NAC) is the precursor for cysteine, a nonessential amino acid. (In case you need a refresher, amino acids are the building blocks of proteins throughout your body. Essential amino acids can't be made by the body, so you need to get them from food. In contrast, nonessential amino acids can be produced by the body, even if your diet doesn't include all of them.) 

Cysteine is also known as "semi-essential" or "conditionally essential," as it can become essential in certain situations, explains Paula Doebrich, MPH, RDN, registered dietitian nutritionist and founder of Happea Nutrition.

In the body, cysteine is used to make glutathione—a powerful, whole-body-relevant antioxidant involved in fighting free radicals, maintaining tissue integrity, and strengthening immune function, notes Doebrich.* NAC itself can also help replenish glutathione1, as it's a stellar source of sulfhydryl groups, which convert into metabolites that promote glutathione synthesis.*

Here's why that's crucial: The body's ability to make glutathione declines over time, starting between 45 and 50 years old2. This is due to the reduced efficiency of cellular signals involved in glutathione production. However, glutathione levels are strongly related to healthy tissue and organ function, and low levels can affect cellular (and thus, whole-body) health3. Therefore, maintaining optimal levels of glutathione throughout life is key for overall health and well-being.*


NAC is a building block precursor for glutathione, a potent antioxidant. This is due to NAC's role as a precursor for cysteine (a key amino acid required to make glutathione) and source of sulfhydryl groups (which supports glutathione synthesis).*

Benefits of N-acetyl-L-cysteine.

To recap: "NAC is not only an antioxidant4 itself, but it also serves as a building block for others—including glutathione, a powerful antioxidant that supports many physiological functions,"* says Emma Engler, M.S., mbg's nutrition research scientist. So, many of the health benefits of NAC stem from its multifunctional role in the body.

Liver detoxification.

When it comes to your body's intrinsic detoxification pathways, your liver is considered the head honcho. Case in point: One of its main roles is to remove waste and toxins5 from your body. To do this, the liver coordinates an elaborate detoxification enzyme system featuring a series of cellular processes. NAC is highly active in phase II detox pathways, making it an important player in the liver's detox actions.*

The antioxidant properties of NAC and glutathione support overall liver function, and ultimately, detoxification.* mbg's vice president of scientific affairs, Ashley Jordan Ferira, Ph.D., RDN, dives deeper: "Metabolically active organs like the liver are generating lots of oxidant byproducts, like free radicals. Indeed, the liver is the body's primary detoxifying organ, so it's busy 24/7. As a source of sulfhydryl groups, NAC is considered a fast-acting antioxidant that helps neutralize oxidants in the liver and in other 'busy' organs. Indeed, NAC and compounds that NAC helps directly replenish (hello, glutathione) are boots-on-the-ground scavengers of those oxidants, supporting the resilience and repair of our liver cells and tissue,"* she explains. 

What's more, the liver and body rely on antioxidants (such as glutathione) to metabolize and remove heavy metals, according to the International Journal of Molecular Sciences6.*

Skin health.

Although the liver is the captain of your body's detoxification system, other organs help steer the ship. This includes the skin, which is a physical barrier7 against unwanted compounds like pollutants, toxins, and byproducts of daily biological processes. And while oxidative stress can affect the skin's natural defense system, the antioxidant actions of NAC and glutathione help support skin health8 by nurturing overall redox balance.*

As Ferira explains, "By working hard to improve our whole-body redox status, NAC is benefiting metabolically active organs in which oxidants and inflammatory processes are at play. NAC is earnestly helping to tip the free-radical scale by promoting antioxidant-to-oxidant balance every day. After all, much of the crux of healthy skin and graceful aging is grounded in antioxidant protection, and thus, cellular resilience and longevity."*

Immune function.

"NAC has antioxidant and anti-inflammatory properties, [so] it can aid the immune system,"* shares Doebrich. Engler explains further: "Your immune system is constantly working to support your body through environmental stressors, but also, everyday biological processes that produce oxidant byproducts that can contribute to oxidative stress. Effective antioxidants—such as NAC—have the power to quench these byproducts (like free radicals), thus combating oxidative stress and supporting immune function at the cellular level. NAC provides support of healthy antioxidant-versus-oxidant balance in the body, helping the immune system function optimally but also providing whole-body benefit.”*

In fact, in a Free Radical Biology and Medicine 9clinical study9 involving postmenopausal women, a daily oral intake of 600 milligrams of NAC "provided significant support for immune defense, likely due to increasing white blood cells' (important cells to the immune system) glutathione reserves,"* notes Engler. In another study, NAC was found to boost antioxidant status, which is essential for top-notch immune function.*    

Brain health.

The brain is highly susceptible to oxidative stress10, but prioritizing your body's antioxidant levels can protect it for years to come. Enter: The antioxidant abilities of NAC and glutathione, which can help protect nerve cells (and therefore, nerve function) by quelling oxidative stress.* 

NAC's anti-inflammatory and vasodilative properties also support brain health11 via vasculature and blood flow, which is critical for delivering oxygen, nutrients, and other bioactives to the brain, says Ferira.* Moreover, according to an article published in Brain Behavior11, NAC is thought to cross the blood-brain barrier, which is critical for targeting brain function.*

Mood support.

Due to its role in glutathione synthesis, NAC may even help maintain well-balanced emotions. For starters, glutathione is one of the most important antioxidants in the brain, where it protects critical cells and tissues from oxidative stress.* 

Glutathione levels are also closely related to mood and behavior, according to a 2020 study12 in Neuroscience & Biobehavioral Reviews.* That said, glutathione precursors (such as NAC) may offer further mood support by helping to increase glutathione levels in the brain.*

Maintaining a healthy weight.

As NAC supports the production of glutathione, it can also support healthy body composition.* It's all thanks to—you guessed it—the antioxidant properties of glutathione.

According to a 2020 scientific review13 from Frontiers, oxidative stress can disrupt the optimal metabolic functioning of fat cells, leading to greater energy stores. Additionally, according to Doebrich, "having lower levels of glutathione could result in less efficient metabolism—i.e., storing more fat." She explains further that the antioxidant properties of glutathione can help control the oxidation of fatty acids, which is required for healthy metabolism (and therefore, healthy weight management).*

Ideal dosage.

Before diving into the ideal NAC dosage, let's chat about form: "For oral dietary supplement applications, there is no research that indicates NAC in a capsule versus powder, gelcap, or tablet would act any differently. I personally find gummy delivery formats of NAC to be a tad paradoxical, given that NAC is fighting oxidants and the sugars in gummies are, well, not!" says Ferira.

She expounds further: "Unlike vitamins, minerals, and some key phytonutrients, the question of ideal dosage for a bioactive like NAC is not a straightforward or easy one. Not because there aren't studies (there are) but because the answer of NAC dose completely depends on the person's health status and targeted health support needs. What we do know is that a sub-efficacious sprinkling of NAC (e.g., less than 100 milligrams per serving) is likely not exerting potent antioxidant effects."

In a compelling clinical study9 from Free Radical Biology and Medicine examining the effects of NAC, a 600-milligram dose improved parameters of immune function.* Likewise, a daily NAC intake of 600 milligrams has been clinically shown to positively affect overall nutritional and antioxidant status.*

"For this reason, I prefer NAC supplements 'playing ball' in the 500-milligram-plus range," notes Ferira. "This science also directly supported the full-potency 600-milligram dose of NAC you'll find in mbg's daily detox+."

"NAC at higher doses, for specific indications, has also been researched. For example: NAC's ability to reduce homocysteine (i.e., a majorly important biomarker for cardiovascular health but also for whole-body methylation functions), as well as its blood-pressure-lowering benefits, have been clinically shown14 to occur at 1.8 grams (1,800 milligrams) of NAC supplementation,"* shares Ferira. "Also, at higher doses (i.e., again, several grams), NAC may help with athletic performance, but that research15 is equivocal and needs to shake out a bit more."* 

Finally, "in other clinical scenarios16 related to pulmonary function and mental health, higher NAC doses (at and above 2 grams) have also shown utility and promise when partnered with a health care practitioner to create a personalized regimen,"* says Ferira. 

Now, if you're unsure whether to take NAC morning or night, Engler has the answer: "There isn't an ideal time of day to take NAC. Though, some choose to leverage its detoxifying and other whole-body benefits first thing in the morning on an empty stomach or with their breakfast."* That's totally up to you!

Additionally, as far as dietary supplements go, NAC tends to play well with others. For example, NAC has complementary action with other antioxidants, such as vitamin C—which you can also find sourced from acerola fruit in mbg's daily detox+.* "However, it's always best to speak with your health care practitioner before adding any new supplement into your routine," notes Engler.

Potential side effects.

In general, NAC is well-tolerated, meaning it's unlikely to cause side effects when consumed at the recommended dosage. At higher dosages (i.e., 1,200 milligrams twice a day), NAC side effects may include gastrointestinal and skin concerns. But even then, such effects are uncommon and an issue of individual variability and sensitivity.

The takeaway.

NAC is a key building block precursor for several antioxidants, including "master antioxidant" glutathione. NAC itself boasts major antioxidant properties, as it works to scavenge free radicals and improve our redox status for cellular protection and longevity.* These actions translate to 360-degree support for liver detoxification, skin health, immune function, brain health, mood, and healthy weight maintenance.*

Needless to say, NAC is right at home in mbg's daily detox+. The formula, which is designed to maximize your daily detox potential, delivers NAC in the clinically researched dose of 600 milligrams.* It also features L-glutathione (in the premium, bioavailable form known as Setria®), milk thistle fruit extract, selenium, and acerola-fruit-sourced vitamin C. Together, this curated cocktail of specialized detoxifiers provides targeted support for your body's natural detox system (since detox is a 24/7 affair).*

If you are pregnant, breastfeeding, or taking medications, consult with your doctor before starting a supplement routine. It is always optimal to consult with a health care provider when considering what supplements are right for you.