By Shellie L. English, Ph.D., Dipl. O.M. (NCCAOM)®, DOM, L.Ac.
In 2020, the supplement N-acetylcysteine, or NAC, gained popularity. NAC’s ability to break down thick mucus has long been used to treat chronic bronchitis, making it a natural choice for combating viral respiratory congestion. Additionally, NAC offers benefits for immunity, detoxification, and brain health. The compound has been used since the 1970s to treat acetaminophen overdose in hospitals, so there is substantial research supporting its effects in the body. NAC is undoubtedly a beneficial supplement, but you can achieve similar results by increasing cysteine in the diet.
When you supplement NAC, it is converted into cysteine, the essential component your cells often lack when producing glutathione. Glutathione is the master antioxidant that aids detoxification and immunity and protects the brain from oxidative stress. By replenishing cysteine, NAC enables your body to produce more glutathione. According to a 2023 review in the journal Antioxidants, raising intracellular glutathione is linked to better immune, metabolic, and neurologic resilience.
Cysteine supply is essential to help the body produce glutathione. In a landmark six-month clinical trial involving older adults, NAC supplementation significantly reduced the rate of symptomatic influenza: Only 25% of those who contracted the flu while on NAC developed symptoms, compared to 79% in the placebo group, as published in the European Respiratory Journal.
The Journal of Brain Sciences published research in February of this year indicating that NAC supplementation shows promise in Alzheimer’s disease studies, as it may support memory and enhance oxidative stress markers related to glutathione detoxification. In trials for NAC use in Parkinson’s, both intravenous and oral administration improved dopamine transporter binding on brain scans and alleviated other symptoms.
NAC is the acetylated form of cysteine, designed for stability and increased bioavailability when used as a supplement. However, increasing cysteine levels does not require taking a supplement. Eating cysteine-rich foods can raise levels, which can then be converted into glutathione. Foods like chicken, eggs, yogurt, lentils, oats, and sunflower seeds are rich in cysteine or its precursor, methionine. Sulfur-rich vegetables such as garlic, onions, leeks, and cruciferous vegetables like broccoli and kale help boost cysteine and glutathione production. Bone broth, gelatin, collagen, and legumes contain glycine, while nuts, tomatoes, and mushrooms provide glutamate. Whey protein, high in cystine, is also a popular and effective way to increase glutathione levels. Additionally, foods or supplements with vitamins C and E, selenium, B6, B12, and folate are important cofactors that help sustain and recycle the glutathione your body produces.
NAC supplementation can provide a safe and effective boost when the body faces additional stress from aging, illness, or environmental toxins. It is generally safe at oral doses of 600 mg to 1,200 mg daily. However, it can interact with nitroglycerin and certain chemotherapy drugs.
Be sure to consult a health care provider before beginning supplementation. Fall is the cold and flu season, so you might consider increasing foods that help raise cysteine levels, which lead to more glutathione and support the immune system. You may also want to keep NAC supplements nearby to help with respiratory symptoms and be immune-ready this fall. Abundant blessings!
