The name—N-acetylcysteine (NAC)—sounds like someone plumbed it from the depths of a biochemistry book. And maybe some scientist did. But as supplements go, this one might be among the most important ones you could take.
NAC has broad benefits to health. Because it contains both sulfur and the amino acid cysteine, NAC serves as a precursor to glutathione—a key antioxidant that provides protection against free radicals and toxins in the body.
Used in Every Hospital
Due to its unique properties and numerous benefits, NAC is used in both conventional and alternative medicine. Every hospital emergency room stocks it as an antidote for acetaminophen (e.g., Tylenol) poisoning. Large doses of acetaminophen, or chronic use at lower dosages, can destroy the liver’s ability to make glutathione, resulting in liver failure and death. NAC restores normal liver levels of glutathione and helps to heal the liver damage caused by acetaminophen. It’s also used in conventional medicine to break down large amounts of mucus, a common symptom of conditions such as emphysema, bronchitis, pneumonia, and chronic obstructive pulmonary disease (COPD).
Just as NAC protects the liver, it also protects the kidneys, which play a key role in detoxification and blood pressure regulation. Doctors use a chemical called a “contrast agent” to make the kidneys more visible when taking medical images of patients. However, this chemical is hard on the kidneys and can result in “contrast-induced nephropathy,” which sometimes can lead to kidney failure. NAC has been found to reduce kidney-related toxicity from contrast agent, and it’s also used to prevent kidney failure in some patients with chronic kidney impairment.
Cold and Flu Shield
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.
Recommendation: 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.
An estimated 10 percent of women of childbearing age have polycystic ovary syndrome (PCOS). The condition is often diagnosed while trying to identify a cause of infertility. PCOS is characterized by enlarged cystic ovaries, high levels of male hormones, obesity, elevated insulin levels, and prediabetes.
In a recent study, doctors discovered that moderately high doses of NAC led to improvements in women with PCOS. Researchers at a leading medical university located in Tehran, Iran, asked 46 women with PCOS to take either 1,800 mg of NAC or placebos daily for six weeks.
The researchers reported in the International Journal of Fertility and Sterility that NAC led to more frequent monthly ovulations, which should improve fertility. The supplements also prompted significant decreases in weight, body-mass index, and waist-to-hip ratio. In addition, the women’s fasting blood sugar, insulin levels and insulin resistance, total cholesterol, and LDL cholesterol decreased. Meanwhile, their HDL (good) cholesterol levels improved.
Recommendation: In addition to other treatments a doctor might suggest, consider taking 600 mg of NAC three times daily.
Mood, Behavior, & Addiction Therapy
The latest frontier in NAC research has focused on mood and behavior issues, especially addictions. NAC appears to influence the activity of several important neurotransmitters that can help improve brain chemistry.
Intriguing evidence suggests that NAC might help people with obsessive-compulsive disorder (OCD). In studies conducted at the University of Minnesota School of Medicine, Minneapolis, researchers treated patients with compulsive hair pulling, nail biting, or skin picking. Their OCD behavior ceased after taking 1,200–2,400 mg of NAC daily. Another study by the same team of researchers found that daily use of NAC supplements reduced obsessive-compulsive gambling within a matter of weeks.
Studies have also shown that NAC—600 mg, four times daily—can reduce the desire for cocaine and blunt positive associations with cocaine-related paraphernalia. In a study conducted at the Medical University of South Carolina, Charleston, nine of 16 patients stopped using cocaine, and five substantially decreased their use of the drug after taking NAC. Preliminary research also suggests that NAC might help reduce the desire for alcohol.
Recommendation: Addictions are very difficult to treat, so consider a variety of approaches, such as a 12-step program, better eating habits, and a well-rounded supplement program. Add 600 mg of NAC two to four times daily.
Other Uses for NAC
Research shows a remarkable range of benefits from NAC supplements. Several studies have shown that NAC improves breathing in people with either pulmonary fibrosis or COPD. NAC might also help people undergoing conventional treatment for schizophrenia. Despite its strong sulfur smell, NAC is exceptionally safe. The only caution is for people who take nitroglycerin for angina pain: NAC can amplify the drug’s effects and lower blood pressure.
3 Cold and Flu Essentials
In addition to NAC, supplement with the following nutrients to keep your immune system in tip-top shape:
Best NAC Detox Regulators has 600 mg of NAC per capsule, with added selenium and molybdenum for better glutathione production.
Lung, Bronchial, & Sinus Health is a combination of NAC and herbs. Smokers and asthmatics give this product great online reviews.
Liver Guard is a comprehensive and targeted formula. NAC, along with silymarin from milk thistle and other nutrients, aid the liver.
Immune Health Essentials
Primadophilus Reuteri vcaps contains Lactobacillus reuteri, a probiotic strain shown to boost the body's absorption of vitamin D.
Vitamin D3 Gummies come in a tangy Wild Berry flavor and have 1,000 IU of vitamin D3 per gummy for immune support.
In a recent study, doctors found that moderately high doses of NAC led to improvements in women with polycystic ovary syndrome. (PCOS).
The latest frontier in NAC research has focused on mood and behavior issues, especially addictions. NAC appears to influence the activity of several important neurotransmitters that can improve brain chemistry.
Jack Challem, BA, ASN, is one of America's most trusted nutrition and health writers and a member of the American Society for Nutrition. Based in Tucson, Ariz., he is the bestselling author of more than 20 books, including No More Fatigue and The Food-Mood Solution. His website is nutritionreporter.com.