NAC: A Helpful Nutrient for Smoking Cessation, COPD, PCOS, Addiction, and Obsessive Rituals

N-acetylcysteine Addiction Dr. Eric Viegas Naturopathic Medicine Ottawa


N-Acetylcysteine: A Helpful Nutrient for Smoking Cessation, COPD, PCOS, Addiction, and Obsessive Rituals


Dr. Eric Viegas, ND


Cysteine is a sulfurous amino acid found in garlic, broccoli, brussel sprouts, oats, lentils, eggs and meat. Interestingly, sheep require cysteine in order to produce larger quantities of wool. Just like sheep, humans need dietary sources of cysteine because we can’t make it on our own. Cysteine can combine with glycine and glutamate to form glutathione (GSH); one of your body’s key antioxidants. GSH is synthesized in the lungs, and by its main reservoir, in the liver.1 Damage from free radicals, peroxides, and heavy metals is severely limited by adequate levels of GSH.


If these benefits sound appealing, and you’re about to reach for that bottle of reduced GSH, don’t bother. Oral GSH use does not raise the levels of GSH in your bloodstream.2 Instead, SAMe, Vitamin D3, and NAC are nutrients that have been shown to increase levels of GSH in the human body.3,4 This article will focus on NAC’s long use as a safe adjunct to treatments, and as a therapy on its own.


NAC, or N-acetylcysteine, is a dietary supplement that was originally created to combat liver toxicity from tylenol/acetaminophen overdose; the most common cause of poisoning worldwide.5 Currently, there is a growing body of evidence favouring the use of NAC as an adjunctive therapy for various addictions, mental illnesses, hormonal & metabolic problems, and cancer-related conditions.6,7


In 2002, 37 women with polycystic ovarian syndrome (PCOS) and insulin resistance were treated for 6 weeks with 1800-3000 mg/day of NAC. Researchers noted that women treated with NAC had increased insulin sensitivity compared to controls 8 ; their bodily tissues more readily responded to insulin and pulled sugars out of their bloodstream. In addition, NAC induced a significant reduction in testosterone levels. High levels of testosterone are implicated in the worsening of PCOS symptoms.  


NAC restores glutamate concentrations which then stimulates group II mGluR receptors. Glutamate transmission is inhibited and reduces the perceived reward of nicotine.9 In a 2011 3.5 day-long double-blind pilot study, smokers were given 3600 mg/day of NAC or placebo.The group smoked an average of 17.5 cigarettes per day, but they refrained from smoking during the study. When participants were given a cigarette after the trial concluded, those that received NAC reported less satisfaction from smoking that cigarette than individuals in the placebo group.9 Moreover, the NAC group reported less withdrawal symptoms than the placebo group.9 It is important to consider that no addiction therapy is truly successful in the long-term without the help of counselling. Cigarette cravings were not reduced in the NAC group compared to placebo.


Chronic obstructive pulmonary disease (COPD) is a common complication from a history of tobacco use. COPD patients given 600-1800 mg/day of NAC for 2 months had improved red blood cell function, and decreased peroxide levels by up to 54%.1 Mucus hypersecretion in the lungs by elastase activity, and severity of cough also decreased. NAC is also a strong mucolytic, meaning it can break down the chemical bonds in mucus, and allow it to be excreted more easily. The mucolytic activity of NAC makes it a promising nutrient in other respiratory concerns like cystic fibrosis, asthma, sinusitis, and seasonal allergies. To cap things off, NAC can protect DNA in the respiratory and digestive tracts from damage; DNA damage is one of the first steps in carcinogenesis.7


NAC has also demonstrated promising outcomes in cocaine addiction, and bipolar disorder when combined with counselling and medication.6 After 8 weeks of 1800 mg/day of NAC, 16 of 29 pathological gamblers experienced significant reductions in gambling behaviour.6  Since Obsessive Compulsive Disorder (OCD) shares similarities with addiction in terms of brain region activity, NAC may benefit obsessive rituals. Only one case report exists of NAC use in OCD. The patient initially only partially responded to antidepressant medication. With the addition of 3000 mg/day of NAC for 13 weeks, the patient showed improvements in control of compulsive washing and obsessional triggers.6  Trichotillomania (TTM), a grooming disorder where patients obsessively remove body hair, may also benefit from NAC supplementation. 45 women and 5 men with TTM were given 1200 mg/day of NAC, or placebo, for 6 weeks. In the second 6 week period, the dosage was increased to 2400 mg/day of NAC. The participants also received psychotherapy and were medicated. At week 9, and until the end of the study, symptoms of TTM decreased in the NAC group compared to placebo.6


NAC is a nutrient with a long history of safety and efficacy. For more information on the benefits of NAC, and to find out if it is right for you, consult your Naturopathic Doctor.



  1. Dekhuijzen PNR. Antioxidant properties of n-acetylcysteine: their relevance in relation to chronic obstructive pulmonary disease. Eur Respir J 2004; 23: 629-636.
  2. Allen J, Bradley RD. Effects of oral glutathione supplementation on systemic oxidative stress biomarkers in human volunteers. J Altern Complement Med 2011; 17(9): 827-833.
  3. Garcion E, et al. New clues about vitamin D functions in the nervous system. Trends in Endocrinology and Metabolism 2002; 13(3): 100-105.
  4. Lieber CS. S-adenosyl-L-methionine: its role in the treatment of liver disorders. The Amer J Clin Nutr 2002; 76(5): 1183-1187.
  5. Gunnell D, et al. Use of paracetamol (acetaminophen) for suicide and nonfatal poisoning: worldwide patterns of use and misuse. Suicide & Life Threatening Behaviour 2000; 30(4): 313-326.
  6. Dean O, et al. N-acetylcysteine in psychiatry: current therapeutic evidence and potential mechanisms of action. J Psychiatry Neurosci 2011; 36(2): 78-86.
  7. De Flora S, et al. Mechanisms of n-acetylcysteine in the prevention of dna damage and cancer, with special reference to smoking-related end-points. Carcinogenesis 2001; 22(7): 999-1013.
  8. Fulghesu AM, et al. N-acetyl-cysteine treatment improves insulin sensitivity in women with polycystic ovary syndrome. Fertility and Sterility 2002; 77(6): 1128-1135.
  9. Lianne S, et al. Efficacy of n-acetylcysteine in the treatment of nicotine dependence: a double-blind placebo-controlled pilot study. Eur Addict Res 2011; 17: 211-216.



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