N-acetylcysteine (NAC)

N-acetylcysteine (NAC), also known as N-acetyl-L-cysteine or just acetylcysteine is the acetylated variant of the amino acid L-cysteine which is an excellent source of sulfhydryl (SH) groups of antioxidants. It is basically the amino acid cysteine with an acetyl group attached to the nitrogen atom. NAC does not occur naturally in significant levels in food. It is chemically synthesised by modifying cysteine, which can be found in many foods such as meat, eggs, dairy, fish, beans, broccoli, nuts, etc. NAC is also available as a cost effective over-the-counter supplement.

The most common clinical uses of NAC is the treatment of acetaminophen (Tylenol-Paracetamol) overdoes poisoning and as a mucolytic agent for treatment of chronic bronchitis and other pulmonary diseases. However, it appears to also have beneficial effects in conditions characterized by decreased GSH or oxidative stress, such as HIV infection, cancer, heart disease, and cigarette smoking. By facilitating GSH biosynthesis, NAC serves an indirect antioxidant role where it can enhance glutathione activity. It is converted in the body into metabolites capable of stimulating glutathione (GSH) synthesis, promoting detoxification, and acting directly as free radical scavengers. Related Article: Increase Glutathione For A Long Healthy Life

In early 2010, it was discovered that NAC offers dual protection against bird flu. It inhibits both virus replication and expression of pro-inflammatory molecules in cells infected with H5N1 virus, holding out the promise of effective protection in the event of a global avian flu pandemic. NAC has also proven extremely effective against seasonal influenza and flu-like illnesses.

Polycystic Ovary Syndrome
In a double-blind, placebo-controlled study of 150 women suffering from infertility who had not responded to treatment with the fertility drug clomiphene, use of NAC at 1,200 mg daily significantly augmented the effectiveness of clomiphene. Treatment was begun on day 3 of the menstrual cycle and continued for 5 days. About 20% of women in the NAC plus clomiphene group became pregnant, as compared to 0% in the placebo plus clomiphene group.

Mental Disease
Research suggests that people with depression have too little glutathione. The use of NAC has been studied in disorders including addiction, compulsive and grooming disorders, schizophrenia and bipolar disorder. Some specific addiction examples include: reduced marijuana dependence, decreased nicotine addiction, decreased cocaine addiction and reductions in gambling behavior associated with pathological gambling. Replicatory trials in bipolar disorder, schizophrenia, and depression are currently under way in Geelong, Australia conducted by Dr. Michael Berk of Barwon Health & Deakin University.2013

Individuals with HIV usually have decreased GSH and cysteine levels. The net loss of sulfur in asymptomatic HIV+ patients is equivalent to a mean loss of about 10 g of cysteine per day. NAC can completely inhibit inflammatory stimulations of HIV replication by supplementation of GSH.

N-Acetylcysteine may aid in diabetes management, suggests a 2006 study from the Journal of Basic and Clinical Physiology and Pharmacology. Involving 32 patients with type 2 diabetes and 15 healthy controls, the study found that three months of treatment with N-acetylcysteine helped regulate glutathione levels in diabetes patients. The study's authors suggest that regulating glutathione levels may help protect against diabetic complications brought on by free radical-induced damage.

Cancer Chemopreventive Agent
The antimutagenic and anticarcinogenic properties of NAC could be ascribed to multiple protective mechanisms, such as NAC nucleophilicity, antioxidant activity, its ability to act as a precursor of intracellular reduced GSH, modulation of detoxification, and DNA repair processes. On these grounds, NAC has emerged as a most promising cancer chemopreventive agent. NAC blocks cancer development at virtually every step in the process, and through multiple mechanisms, making it an important cancer chemopreventive agent.

Athletic Use
N-acetylcysteine has been shown to delay fatigue during both short intense intermittent exercise and prolonged exercise. Additional studies have also shown that supplementation with n-acetylcysteine can reduce post-exercise muscle soreness following heavy eccentric exercise. In each of these studies, n-acetylcysteine worked by increasing cysteine/glutathione levels and by minimizing the adverse effects of free radicals on muscle contraction and damage.

Angina Pectoris
Angina pectoris is a squeezing feeling in the chest caused by inadequate blood supply to the heart. It can be a precursor of heart attacks. People with angina often use the drug nitroglycerin to relieve symptoms. One 4-month, double-blind, placebo-controlled study of 200 people with heart disease found that the combination of nitroglycerin and NAC significantly reduced the incidence of heart attacks and other severe heart problems. NAC alone and nitroglycerin alone were not as effective. The only problem was that the combination of nitroglycerin and NAC caused severe headaches in many participants. You should not try to treat chest pain on your own. Always see a doctor.

- Side effects common to high oral doses include nausea, vomiting, and other gastrointestinal disturbances.
- Intravenous administration has been shown, in some cases, to cause allergic reactions usually in the form of rash or angioedema.
- Combination of Nitroglycerin and NAC can cause severe headaches.
- Safety in young children, women who are pregnant or nursing, and individuals with severe liver or kidney disease has not been established.
- A 2007 study in laboratory mice,  has raised a 'theoretical concern' that 'chronic' NAC administration in those animals might produce a condition called pulmonary arterial hypertension. There have been no further publications supporting this one-time observation made in an animal model using doses 10-20 times those suggested for long-term human supplementation. By contrast, there have been numerous studies demonstrating human benefit from NAC supplementation at moderate doses (1,200-1,800 mg per day) over the course of nearly 4 decades.

Always consult your health care provider before starting a supplement therapy.