Few natural substances appear to fight colds and flu as effectively as NAC. In a remarkable study, Silvio De Flora, MD, of the University of Genoa, Italy, and his colleagues asked 262 seniors to take either 600 mg of NAC or placebos twice daily for six months during cold and flu season. Incredibly, few of the subjects taking NAC developed flu symptoms, even though blood tests confirmed they were infected with the flu virus. And of the subjects who did develop symptoms, those taking NAC experienced generally mild symptoms compared with those taking placebo.
Other studies support the broad benefits of NAC in the treatment of infections. A Stanford University study of AIDS patients found that those who took several grams of NAC daily lived significantly longer than those who declined the supplement. Meanwhile, a study in Sweden showed that people taking NAC missed 38 percent fewer sick days from work due to chronic bronchitis, compared with those who took placebo.
Take 500-600 mg daily throughout the year, but double this amount during cold and flu season. At the first sign of cold or flu symptoms, increase the amount to 1,000 mg, three to four times daily.