NAC or N-acetyl cysteine is another form of the amino acid cysteine which is where NAC is derived from. Cysteine can be found in most high protein foods but NAC is not actually found in the diet. Cysteine can be synthesized in the body whereas NAC cannot. Many people are choosing to take NAC as a supplement because there are several benefits that it can give you that regular cysteine alone cannot. First and foremost, NAC is found to relieve many of the flu and cold symptoms. Most notably, it helps to break down mucus and can improve the quality of breathing for people with chronic bronchitis or COPD. It has an antioxidant property that also helps protect lung tissue as well. It does this by helping the body synthesize another important antioxidant called glutathione. When this happens it can protect the liver from some of the problems it can face through toxins and chemicals. Along with this it helps to prevent the body from acetaminophen toxicity and is used for many patients that need treatment for acetaminophen poisoning. It also works for hepatitis toxicity as well. NAC supplements also have been shown to reduce the production of some cells that line the colon which can help to reduce the chances of colon cancer for people who have found polyps in their colon. Although technically no deficiencies in NAC have ever been found, it is the deficiency in cysteine that can be helped with NAC which occurs with many patients, especially in HIV infected people. NAC should be taken by people who are suffering from one of the above mentioned ailments, and is not necessarily for completely healthy people. If you feel that you may benefit from NAC, it is important to talk to your doctor to see if it something that you can use to heal one of your ailments.