How NAC Supplements Fight Colds, Flu and Much More

December 7, 2012
Bottom Line's High Energy for Life
Richard Firshein, DO

You know all about the benefits of fish oil…and magnesium…and vitamin D. But here’s a supplement that far fewer people are taking—but many could benefit from. It’s called n-acetylcysteine (NAC)—and it’s especially helpful during cold and flu season since it can combat respiratory ailments. But wait, there’s more. NAC also can ease lung and liver problems. To get this amazing remedy on your radar, we turned to Richard Firshein, DO, director of The Firshein Center for Comprehensive Medicine in New York City, and asked him why he recommends NAC to so many of his patients. Here’s what he told us…


NAC is an amino acid—and a building block of glutathione, one of the most powerful antioxidants in the body. It helps the body combat damaging free radicals and stimulates other antioxidants in the body to do their beneficial work. In addition, NAC has many uses in the body. Specifically, it can help you…

Fight colds and flu. NAC is a remedy often recommended by holistic doctors to prevent—and reduce symptoms of—the flu. A well-known Italian study published in European Respiratory Journal found that only 25% of people who took NAC and were injected with a flu virus developed flu symptoms compared with 79% who received a placebo. You also can consider taking NAC when you notice the first signs of a cold.

Protect your lungs. NAC protects the lungs by helping to make glutathione in the lining of the lungs. NAC also can act as a buffer against pollution. When you have a cold, taking NAC can protect your lungs from complications such as bronchitis. In people who have chronic obstructive pulmonary diseases such as emphysema, NAC can help reduce the buildup of mucus and congestion which, in turn, can help relieve the chronic cough that often accompanies emphysema. NAC also is recommended for people with pulmonary fibrosis, since it may slow the disease.

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Detox the liver. NAC is known to help cleanse the liver—it helps people whose livers are damaged either because of alcoholism or elevated liver enzymes. Elevated liver enzymes can occur in people who have hepatitis or heart failure or who are obese.


NAC is found in small amounts in some protein-rich foods such as pork, poultry and yogurt. But to really get its health benefits, you have to take it as a supplement. NAC is available at most health-food stores and drugstores.

Dr. Firshein usually recommends that his patients take between 500 mg and 1,000 mg daily of NAC to fight the common cold or flu…protect lungs…and detox the liver. Since every patient is different, it’s important to check with your own holistic doctor about the amount of NAC that’s right for you. This is especially important for patients with liver or lung diseases.

There are no side effects associated with NAC, although higher doses can cause digestive upset. People with heart or kidney disease should speak to their doctors first before taking NAC.

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NAC can be taken on its own, but it’s best to take it with other antioxidants, such as vitamin C, since NAC works better in conjunction with other antioxidants. The detoxification process may create toxic by-products that linger in the body. If there’s a lot of toxicity, the other antioxidant can lend a hand clearing out the excess toxins.