NAC (N-Acetylcysteine) Supplements

Best N-AcetylCysteinIn nutrition and fitness circles, N-acetylcysteine (NAC) is hailed as somewhat of a panacea – a medicine that cures all. Let’s be real, there are no “magic bullets”, but NAC does come close. In fact, it can be a lifesaver…

N-acetylcysteine is the go-to treatment for acetaminophen overdose. Acetaminophen is an over-the-counter pain killer that can cause some significant liver damage when taken in high doses, which can ultimately lead to a delayed and gnarly death. It’s a testament to the strength of NAC that it has been shown to protect 100% of the liver when given within 8 hours of acetaminophen overdose [1]. Its main life-saving action here is from its roles as a superstar antioxidant:

Double Antioxidant Action of N-AcetylCysteine

The NAC molecule itself is a cysteine amino acid with extras attached to keep it stable and bioavailable. Once NAC has been absorbed, cysteine acts as an antioxidant in two ways:

1. Cysteine Chelates Harmful Metals

a free amino acid, cysteine chelates or attaches to any metals it comes across. By binding to these harmful metals, cysteine stops them from causing oxidative damage to cells.

  • Two case studies have shown that taking an NAC supplement can lower metals in the blood after metal-on-metal hip implants. The participants took 300mg of NAC per kilogram of body weight for 9 days. [2]

2. Cysteine Increases Glutathione

NAC Supplements

Glutathione (GSH) is the most abundant and widely distributed antioxidant in the body. It is created by combining cysteine with two other amino acids: glycine and glutamine. Cysteine (from NAC) is the rate-limiting step – this means that low levels of cysteine will stop glutathione from being produced. More cysteine = more glutathione.

Glutathione is found in almost every cell of the body where it:

  • Maintains cell function
  • Protects against cell damage from free radicals
  • Enables the immune system to function properly
  • Regulates cell proliferation
  • Reduces inflammation [3]

Sounds great, right? So why take NAC supplements instead of glutathione? Research shows that NAC supplementation is much more effective than taking glutathione because of their different levels of bioavailability. Oral glutathione it is easily broken down in the stomach and liver, while NAC resists these processes. NAC supplementation boosts glutathione within minutes.

As a potent chelator and glutathione precursor, N-acetylcysteine is effective for:

  • Supporting liver detoxification (different pathway than Tudca supplements).
  • Improving exercise performance and recovery.
  • Boosting the immune system. Taking 600mg per day has been shown to support the immune system, prevent recurring infections and speed up healing.
  • Supporting healthy ageing.
  • Supporting the treatment of degenerative diseases that involve oxidative damage such as Parkinson’s disease. [4][5][6]

NAC for recovery

N-Acetyl Cysteine for Addiction Recovery & Mental Health

Cysteine, the amino acid derived from NAC, has major impact on brain chemical pathways. Once it has been cleaved from the NAC molecule, cysteine is believed to travel down one of two pathways:

  1. Cysteine joins with other amino acids to become glutathione, as previously discussed.
  2. Cysteine modulates the glutamate system.

Glutamate (from the amino acid, glutamic acid) is an excitatory neurotransmitter in the brain.

Translation: it makes the brain excited. Research suggests that changes to glutamate activity can be linked to addictions of all kinds and contributes to poor impulse control [5]. NAC is able to regulate the glutamate system too keep it on an even keel – it stops levels from getting too high or too low, reducing cravings and improving self-control.

  • Studies have suggested that NAC may have a role in supporting recovery from addiction to cocaine by restoring healthy glutamate levels [7] [8].

N-acetylcysteine has been studied for its use in chronic mental health conditions, too. The boost that NAC gives to glutathione can have massive effects on the nervous system. Nerve cells contain huge amounts of glutathione where it acts as an antioxidant to prevent damage to the nerves, but it also has another role – Glutathione is a reservoir of important neurotransmitters: cysteine, glycine, and glutamine. Nerve cells release glutathione, it gets broken down into these smaller amino acids, and they are used in nerve transmissions. By boosting glutathione, it may be possible to improve nervous system function.

  • N-acetylcysteine has been studied for its positive results as a complementary treatment for bipolar disorder, OCD, schizophrenia, and depression [9].

N-acetylcysteine shouldn’t be used as a frontline therapy for mental health problems – there isn’t enough evidence to suggest that it is effective enough to rely on in place of medication or therapy. But given the great results it’s getting in mental health research, it should be considered as a complementary component of a full therapeutic plan.

NAC for athletes

N-Acetylcysteine For Exercise Performance & Recovery

Cellular energy production naturally creates a lot of reactive oxygen species. The energy demands of exercise speed up this process, and free radicals can quickly cascade and cause oxidative stress, cell destruction and tissue damage.

Oxidative stress contributes to:

  • Muscle fatigue during activity
  • Muscle, joint and ligament stiffness
  • Slow recovery time
  • Inflammation

NAC has been shown to boost levels of glutathione within muscle tissue to combat the increased level of exercise-induced free radicals. This means better performance, quicker recovery, and fewer injuries!

  • A 2014 study showed that triathletes who took 1,000mg of NAC per day for 9 days had greater sprint performance, reduced exercise-related oxidative damage and inflammation, and quicker recovery [10].

N-Acetylcysteine and Mucus

As an antioxidant, NAC is a great immune-booster to prevent illness and speed up recovery. But did you know it can also help you to breathe better? If you’re feeling clogged up with mucus, N-acetylcysteine could be what you need – NAC is able to break down the disulphide bonds that hold mucus together, which means that it stops mucus from being too viscous and elastic.

Translation: NAC can thin out your snot so you can blow it out or cough it up easier. Better out than in!

It has been used to treat chronic obstructive pulmonary disease, pneumonia, and chronic bronchitis, as well as the common cold and influenza. If you’re having a hard time blowing your nose, give NAC a try.

How to Take N-Acetylcysteine Supplements

How Much Should I Take?

Exercise & Training: A moderate dose of 600mg per day will help to improve performance and recovery, but serious athletes may need to take up to 1g per day.

Mental Health & Addiction: 300mg – 600mg of N-acetylcysteine per day may help to improve symptoms alongside conventional therapies and prescribed medications. Seek advice from a qualified nutritionist if you are considering taking higher doses.

To Break Down Mucus: Depending on the severity of the condition, 300mg – 600mg per day is a good place to start.
General Well-being & Anti-Ageing: 300mg per day of N-acetylecysteine is a good dose for most people to support glutathione production and antioxidant action throughout the body.

When Should I Take N-Acetylcysteine?

Because it is an amino acid, N-acetylcysteine should be taken 30 minutes before or after food. Amino acids compete for absorption, so keep it separated from protein shakes, too!


  1. N-acetylcysteine supplements have very few side effects for most people. Some adverse reactions include nausea, vomiting and diarrhoea. Some people find they become “snotty” when they start taking NAC as it breaks down mucus to be easily eliminated out of the body. Very few people experience rashes, headache and drowsiness from NAC supplementation.
  2. Take at least 1 hour away from other medications.
  3. Check with your prescribing physician or pharmacist if there are interactions with NAC and your medications.

The 5 Best N-Acetylcystine Supplements

#5 Designs for Health N-Acetyl-L-Cysteine (900mg 120 capsules)

NAC N-acetyl Cystein supplement

With a whopping 900mg of N-acetylcysteine in each capsule, this supplement by Designs for Health packs a punch. Gluten-free, vegan-friendly and GMO-free, this is a clean, effective supplement that makes it easy to take a therapeutic dose in just one capsule.

#4 BioAdvantexPharma PharmaNAC Effervescent N-Acetylcysteine (900mg 24 tablets)

Pharmaceutical NAC

Flavored “pink berry blast” – this NAC supplement tastes amazing! PharmaNAC is an effervescent N-acetylcysteine supplement with safe ingredients like natural flavors, citric acid, and sodium, and 900mg of NAC per tablet. This is a great supplement to take if you have difficulty swallowing pills and dislike granule residue from powdered forms of NAC. This one really dissolves! Perfect to pop in your drink bottle and sip on during a workout to improve exercise performance and recovery.

#3 Bulk Supplements N-Acetyl-L-Cysteine (250g Powder)

NAC Powder

Athletes and budgeters, look no further – this may be the cheapest, cleanest, simplest NAC on the market. Each bag contains only powdered N-acetylcysteine – no additives, fillers, binders or flavors. Taking ¼ of a teaspoon will give you 600mg of NAC, making it the best supplement if you regularly adjust your dose or if you need to take high doses. Best of all, you can’t beat the price! The more you buy, the more you save – Bulk Supplements offer three sizes: 250g bags, 1kg bags and 5kg bags.

#2 NOW NAC (600mg 250 capsules)

NAC Supplements

NOW have developed an N-acetylcysteine supplement with antioxidant minerals: molybdenum and selenium. These two nutrients are key cofactors for glutathione synthesis and regeneration, making this supplement a great way to boost your antioxidant defences, support your immune system, and fight off any lingering infections.

With 600mg per capsule, NOW NAC makes it easy to take just one capsule per day to reach a therapeutic dose.

#1 Nature’s Sunshine N-Acetyl Cysteine (300mg 60 tablets)

Best NAC Supplement

Nature’s Sunshine is a trusted brand that has been in the supplement industry for decades. Their NAC comes in 300mg doses, making it a great choice if you want to start on a low amount, or split your dose across the day.

Rather than manufacturing the N-acetylcysteine into a capsule, Nature’s Sunshine have compounded it into tablet form and added turmeric for extra antioxidant action and to act as a natural preservative. If you’re looking for a NAC supplement from a brand that guarantees high quality ingredients, you’ve found it.

View Nature’s Sunshine NAC on Amazon Here

Further Reading:

  • [1] Farrel, S. E. (2017) Acetaminophen Toxicity & Treatment Management.
  • [2] Giampreti, A., et al. (2016) N-Acetyl-Cysteine as Effective and Safe Chelating Agent in Metal-on-Metal Hip-Implanted Patients: Two Cases. Case Reports in Orthopedics.
  • [3] Kerksick, C. & Willoughby, D. (2005) The Antioxidant Role of Glutathione and N-Acetyl-Cysteine Supplements and Exercise-Induced Oxidative Stress. J Int Soc Sports Nutr., 36 – 44.
  • [4] Holmay, M. J., et al. (2014) N-acetylcysteine Boosts Brain and Blood Glutathione in Gaucher and Parkinson’s Diseases. Clin Neuropharmacol., 36:4, 103 – 106.
  • [5] Arranz, L., et al. (2008) The glutathione precursor N-acetylcysteine improves immune function in postmenopausal women. Free Radic Biol Med., 45:9, 1252 – 1262.
  • [6] Kerksick, C. & Willoughby, D. (2005) The Antioxidant Role of Glutathione and N-Acetyl-Cysteine Supplements and Exercise-Induced Oxidative Stress. Journal of the International Society of Sports Nutrition, 2:38.
  • [7] Moran, M. M., et al. (2005) Cystine/Glutamate Exchange Regulates Metabotropic Glutamate Receptor Presynaptic Inhibition of Excitatory Transmission and Vulnerability to Cocaine Seeking. 25:27, 6389 – 6393.
  • [8] Baker, D. A., et al. (2003) Neuroadaptations in cystine-glutamate exchange underlie cocaine relapse. Nat Neurosci., 6:7, 743 – 749.
  • [9] Dean, O., et al. (2011) N-acetylcysteine in psychiatry: current therapeutic evidence and potential mechanisms of action. Journal of Psychiatry & Neuroscience, 36:2, 78 – 86.
  • [10] Slattery, K. M., et al. (2014) Effect of N-acetylcysteine on cycling performance after intensified training. Med Sci Sports Exerc., 46:6, 1114 – 1123.
    [11] Gass, J. T. & Olive, M. F. (2008) Glutamatergic substrates of drug addiction and alcoholism. Biochem Pharmacol., 75:1, 218 – 265.
About James Lyons

James Lyons (BHSc Nutritional Medicine) is a clinical nutritionist, medical writer, and educator. He specialises in plant-based nutrition and is passionate about improving public access to reliable and accurate health information.

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