N acetyl cysteine, commonly known as NAC, is one of my favorite supplements for the majority of chronic illnesses. Cysteine is a conditionally essential sulfur-containing amino acid found in most high protein foods and synthesized from dietary methionine and serine. It makes up one of the three amino acids required for glutathione synthesis along with glycine and glutamic acid. Glutathione is the body’s primary antioxidant and is required for DNA synthesis, normal immune function, reducing oxidative stress, regulating enzyme function, regenerating vitamins C and E, assisting normal cell death, sperm cell formation, eliminating toxic elements, and more. Numerous chronic illnesses and lifestyle choices can deplete glutathione levels even if dietary amino acid levels are adequate.

Intravenous NAC is used in hospitals to prevent kidney and liver damage after acute acetaminophen toxicity, reduce toxicity from certain chemotherapy drugs, reduce rejection of transplant organs, and prevent damage from radioactive contrast dyes used for imaging. In clinical trials, oral NAC supplements have been used to reduce oxidative stress and inflammation in patients with cardiovascular disease, diabetes and insulin resistance, obesity, respiratory ailments, and ulcerative colitis. Besides reducing oxidative stress, studies on patients with cardiovascular disease, including hypertension, also showed that NAC increases nitric oxide production, increasing vein dilation and improving blood flow and blood pressure. In patients with non-alcoholic fatty liver disease, supplemental NAC improved liver function within three months. In clinical trials on infertility from PCOS, supplemental NAC along with the medication clomiphene citrate resulted in increased ovulation and pregnancy rates. In women with recurrent pregnancy loss (RPL), supplemental NAC along with folic acid resulted in an increase in viable pregnancies compared to folic acid alone; this may be due to the sulfur content of NAC as well as its antioxidant effects as SULF1 gene mutations have been implicated in some instances of RPL. In men with infertility, NAC combined with selenium improved semen quality and, in men with infertility from varicocele, NAC combined with surgery improved semen integrity and increased partner pregnancies compared to surgery alone. In patients with respiratory ailments such as asthma, chronic bronchitis, and COPD, NAC also acts as an mucolytic, thinning out mucus in the lungs and reducing symptoms, besides reducing inflammation. In patients with HIV, supplemental NAC improves immune function, resulting in restoration of natural killer cells. NAC may also help regulate glutamate levels, an excitatory neurotransmitter that has been implicated in psychiatric disorders. Clinical trials on patients with addictive behaviors, bipolar disorder, depression, and OCD show that supplemental NAC combined with conventional therapies may reduce symptoms and improve function. NAC may also help reduce brain inflammation and balance glutamate levels in patients with neurodegenerative disorders such as Alzheimer’s and Parkinson’s disease and memory and brain disorders associated with aging. More clinical trials on these health issues are required.

Side-effects of NAC are rare but may include constipation, diarrhea, drowsiness, fever, headache, low blood pressure, nausea, skin rash, and vomiting. Contraindications includes anticoagulant and antiplatelet drugs and nitroglycerin. NAC may cause false positives on liver enzyme tests; elimination of NAC for 2-3 weeks may be necessary prior to liver enzyme tests.

Standard dosing of oral NAC is 600mg once or twice daily. Since it may cause drowsiness, some people find it best to take at night. I prefer sustained release formulas as they seem to be more effective.

Disclaimer: The content herein is not intended to be a substitute for professional medical advice. It is not meant to diagnosis, cure, or treat any medical condition. Always consult a physician or other qualified healthcare provider with questions regarding a medical condition and before starting new diets and dietary supplements. Not all diets or supplements are appropriate for all people or all health conditions.

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