The Benefits of N-Acetyl-L-Cysteine for Respiratory Health

Breathing happens so automatically that many of us don’t even notice we’re doing it – until the ability to breathe is thrown off by a respiratory disorder, inflamed lung tissue, or mucous congestion. Adults over the age of 65 who are looking to support their immune function should consider the benefits of N-Acetyl-L-Cysteine (NAC). This often-overlooked nutrient provides an important source of antioxidants and is part of your airways’ first line of defense against respiratory symptoms.

What is NAC?

NAC has been used since the 1960s to help clear congested lungs in patients with chronic respiratory illnesses.[1] It is a water-soluble and more bioavailable form of the semi-essential amino acid cysteine.[2] Once absorbed, NAC is converted to its cysteine form and then used to make the antioxidant glutathione within the liver.[3]

NAC is used as an antioxidant for the maintenance of good health primarily due to its ability to increase the body’s glutathione production. Glutathione is considered by some to be the “master antioxidant” and is found throughout the body’s tissues. It helps protect against oxidative stress and contributes to many other metabolic processes in the body. [4] The catch is that the formation of glutathione relies on a sufficient supply of cysteine.

When you’re sick, more free radicals are generated, which increases your body’s need for the antioxidant glutathione to protect against oxidative stress. This is why low glutathione levels are considered a key sign of illness.

NAC, glutathione, and respiratory health

When it comes to NAC’s benefits, respiratory health really stands out. By stimulating glutathione synthesis, it protects your airways in multiple ways.

NAC’s ability to clear mucus congestion and supply antioxidant defense to the lungs has made it an effective therapy for relieving symptoms of bronchitis, influenza, and chronic obstructive pulmonary disease (COPD). Studies show that supplementation with NAC for up to three years can significantly reduce the number of bronchitis episodes experienced by people diagnosed with chronic bronchitis.[5] NAC is also believed to help with the inflammatory aspect of hyper-responsive lungs that leaves people breathless, coughing, and wheezing when exposed to triggers in their environment.

NAC supports the activity of some immune system cells that rely on glutathione to work properly. This includes the function of cytokines, which are molecules that support cell communication in immune responses, and natural killer cells that respond to infection. NAC also supports the activity of nitric oxide, a molecule that is important to your health because it relaxes the inner muscles of the blood vessels.

Recent clinical evidence suggests that NAC may be helpful for hospitalized patients dealing with acute respiratory distress and lung injury. A review of studies concluded that administering NAC to patients improved their signs of inflammation, as well as the amount of oxygen circulating throughout their bodies while in intensive care.[6]

In addition to infection and disease, your lungs are vulnerable to the pollutants and airborne contaminants that you inhale. The presence of glutathione in lung tissue works as a first line of defense against such toxins, including the high concentration of free radicals present in tobacco smoke.

How much NAC should you take?

Your health, age, diet, and lifestyle all play roles in your body’s need for cysteine. You can acquire some cysteine by eating high-protein foods, such as:[7]

  • Poultry meats
  • Eggs
  • Yogourt
  • Cottage cheese
  • Garlic

Your body is also capable of making some cysteine from the amino acid methionine. Despite this, certain situations can increase your needs. Because the body’s production of glutathione decreases with age, people become more vulnerable to oxidative stress and infection as they get older.[8] This decline is believed to result from a reduced availability of cysteine. Illness, disease, and exposure to toxins, such as from air pollution or tobacco smoke, also increase your need for glutathione to compensate for the resulting oxidative stress.

N-Acetyl-L-Cysteine (NAC) from Natural Factors contains 600 mg of NAC in each vegetarian capsule, which is the same concentration used in some clinical studies. By providing cysteine as a free form amino acid, NAC is one step closer to producing glutathione than when consumed as part of a complete protein from food. This vegetarian-friendly formula is a fantastic option for adults over the age of 65 who would like additional immune system support, including people who are looking to relieve symptoms of chronic bronchitis.

Simple steps to protect your respiratory health

Breathing is essential for life and should not be taken for granted. Changes in your respiratory health or persistent respiratory symptoms, such as shortness of breath or difficulty breathing, can be a sign of a serious problem and should be discussed with your health care practitioner.

You can take simple steps to help protect your airways, such as not smoking, avoiding exposure to airborne pollutants, and wearing a mask in public places during the cold and flu season. Daily supplementation with NAC can also help replenish your levels of the antioxidant glutathione. Make sure to discuss with a health care practitioner before use if you are pregnant, breastfeeding, or have kidney stones. NAC should not be used if you are taking antibiotics or nitroglycerin.

[1] Kasperczyk S, Dobrakowski M, Kasperczyk A, et al. Effect of treatment with N-acetylcysteine on non-enzymatic antioxidant reserves and lipid peroxidation in workers exposed to lead. Ann Agric Environ Med. 2014; 21(2):272-277.

[2] Atkuri KR, Mantovani JJ, Herzenberg LA, et al. N-acetylcysteine – a safe antidote for cysteine/glutathione deficiency. Curr Opin Pharmacol. 2007; 7(4):355-359.

[3] Mokhtar V, Afsharian P, Shahhoseini M, et al. A review on various uses of N-acetyl cysteine. Cell Journal (Yakhteh). 2017; 19(1):11-17.

[4] Teskey G, Abrahem R, Cao R, et al. Glutathione as a marker for human disease. Adv Clin Chem. 2018; 87:141-159.

[5] Cazzola M, Calzetta L, Page C, et al. Influence of N-acetylcysteine on chronic bronchitis or COPD exacerbations: a meta-analysis. Eur Respir Rev. 2015; 24:451-461.

[6] Schloss J, Leach M, Brown D, et al. The effects of N-acetyl cysteine on acute viral respiratory infections in humans: A rapid review. Adv Integr Med. 2020; 7(4):232-239.

[7] PennState Hershey. Cysteine [Internet]. Milton Hershey Medical Center [cited 28 September 2020]. Available from:

[8] Jones DP, Mody VC, Carlson JL, et al. Redox analysis of human plasma allows separation of pro-oxidant events of aging from decline in antioxidant defenses. Free Radic Biol Med. 2002; 33:1290-1300.

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