N-acetyl-L-cysteine (NAC)
N-acetyl-L-cysteine (NAC), a modified form of cysteine, helps break down mucus and detoxify harmful substances in the body. Both cysteine and NAC have been shown to increase levels of the antioxidant glutathione.
Dietary Sources: The body synthesizes cysteine from the essential amino acid methionine. Cysteine is also found in most high-protein foods, including ricotta, cottage cheese, yogurt, pork, sausage meat, chicken, turkey, duck, lunch meat, wheat germ, granola, and oat flakes.
Uses: N-acetyl cysteine (NAC) offers a variety of potential therapeutic uses, particularly in the prevention or in the treatment of the following conditions:
Acetaminophen poisoning
Health care providers commonly administer oral or intravenous (IV) NAC to prevent or reduce liver and kidney damage associated with overdoses of acetaminophen (Tylenol), an over-the-counter (OTC) medication commonly used for pain or headache. Acetaminophen poisoning can occur at lower doses of the drug if someone drinks alcohol or takes certain medications that may damage the liver on a regular basis.
Heavy Metal Detoxification
Heavy metals like lead, mercury and arsenic are detoxified and removed from the body by N-Acetyl Cysteine . It also increases the excretion of zinc and other essential minerals when taken over an extended period. It is therefore necessary to supplement zinc, copper and other trace minerals when taking N-Acetyl Cysteine.
Addiction treatment
A recent study in The American Journal of Psychiatry supported the use of N-acetylcysteine (NAC) for the treatment of cocaine dependance. While taking N-acetylcysteine, at a dose of 600mg twice per day participants reported less desire to use and less interest in response to cocaine related cues.
NAC may reduce craving and symptoms associated with cocaine withdrawal. It has been suggested that NAC may also help to reduced nicotine and heroin cravings further research is required.
Heart disease
In clinical studies of people having a heart attack or those with ongoing chest pain, NAC, in combination with nitroglycerin (a drug that opens up blood vessels and improves blood flow), has been more effective than either NAC or nitroglycerin alone in reducing subsequent chest pain, heart attack, and the risk of death. However, individuals who receive both NAC and nitroglycerin may experience a severe headache. These results are promising, but further human studies are needed to confirm the safety and effectiveness of NAC for heart disease.
A large clinical study found that administering NAC after coronary bypass surgery did not improve outcomes.
Respiratory illness
A review of clinical studies also found that NAC may help dissolve mucus and improve symptoms associated with chronic bronchitis, asthma, cystic fibrosis and emphysema. Chronic smokers also may benefit from NAC supplementation. Clinical studies on large groups of people have found that NAC appears to have cancer prevention properties in people who are at risk for lung cancer.
Free radical damage is believed to contribute to the development and progression of acute respiratory distress syndrome (ARDS), a condition characterized by the rapid and progressive malfunction of the lungs. Although not all clinical studies agree, some research (laboratory and human) suggests that intravenous NAC may boost levels of glutathione and subsequently prevent and/or treat lung damage caused by ARDS. However, results of other studies have been conflicting. Further investigation is needed.
HIV/AIDS
Human immunodeficiency virus (HIV) infection is considered to be a condition of excessive oxidative stress (caused by free radicals) where the antioxidant glutathione is depleted significantly. Therefore, it is believed that supplementation with cysteine may help strengthen the immune system in those with HIV and diminish the bodily damage associated with this infection.
In one well-designed clinical study of people with HIV, those who took a daily supplement regimen including the amino acid glutamine (40 grams per day), vitamin C (800 mg), vitamin E (500 IU), beta-carotene (27,000 IU), selenium (280 mcg), and N-acetylcysteine (2400 mg) gained significantly more weight after 12 weeks than those who took placebo. Similarly, in a smaller-scale clinical study using NAC in HIV positive patients, the supplement did increase glutathione levels while a placebo did not.
These studies and others support the theory that NAC may prove to be a useful addition to conventional medical care for those with HIV. Other clinical studies, however, have shown negative results using NAC for those with HIV. Therefore, more research is needed before conclusions can be drawn about NAC supplements for this infection.
Trichotillomania (Compulsive hair pulling)
According to a study published in the July issue of the Archives of General Psychiatry, “a simple supplement” containing the amino acid N-acetylcysteine “could help treat people with” trichotillomania, “an impulse disorder that manifests in hair-tearing.” People who suffer from trichotillomania have “uncontrollable urges to pluck the hair of the scalp and even eyebrows and lashes, often to the point of baldness.”
During the placebo controlled trial participants received a starting dose of 1,200 milligrams of N-acetylcysteine daily, which was doubled after a period of six weeks if no improvement took place. At the end of the study, 56 percent of the participants were considered to have had improvement in their condition.
Others
Low levels of cysteine may be linked to an increased risk of cervical dysplasia (changes to the opening of the uterus that are precancerous or cancerous). Preliminary evidence also suggests that NAC supplements:
- May improve symptoms associated with Sjögren’s syndrome (an autoimmune disorder characterized by dry mouth and dry eyes).
- Help enhance cognitive functioning in some individuals with Alzheimer’s disease
- Prevent development of cataracts and macular degeneration
- Slow down motor impairment in amyotrophic lateral sclerosis (ALS, often called Lou Gehrig’s disease which is a progressive loss of control of voluntary muscles due to destruction of nerve cells in the brain and spinal cord)
- Help treat hepatitis C when combined with standard medical treatment
- Help increase HDL cholesterol (the good kind of cholesterol)
- Help increase fertility along with fertility drugs in people with polycystic ovary disease
- Help improve outcome in children with advanced cerebral adrenoleukodystrophy, a type of leukemia
- May be useful in treating cocaine addiction. Twenty-three cocaine addicts completely or significantly reduced their use of cocaine during treatment with NAC in a small clinical study.
Further studies are needed to confirm these early findings.
N-Acetyl Cysteine Cautions
Although a great deal of research has shown that NAC has antioxidant activity, one small study found that daily amounts of 1.2 grams or more could lead to increased oxidative stress.
To prevent this Vitamin C is recommended when taking N-acetyl cysteine. Two to three times as much vitamin C can be taken at the same time. The vitamin C helps keep the glutathione that is produced from the Cysteine in its reduced form so that it can continue acting as an antioxidant.
N-Acetyl Cysteine Dosage
Typical dosage recommendations are in the range of 250-1500mg of NAC daily for the majority of therapeutic benefits.
N-Acetyl Cysteine Safety
NAC is considered safe for consumption in its therapeutic dosage ranges.
One study reported that 19% of people taking NAC orally experienced nausea, vomiting, headache, dry mouth, dizziness, or abdominal pain. These symptoms have not been consistently reported by other researchers, however.
Extremely large amounts of cysteine, the amino acid from which NAC is derived, may be toxic to nerve cells in rats.
NAC may increase urinary zinc excretion. Therefore, supplemental zinc and copper should be added when supplementing with NAC for extended periods.
Individual reactions may vary and anyone experiencing adverse symptoms while taking N-Acetyl Cysteine should discontinue it.
We would advise against using NAC supplements when pregnant or breast feeding.
Drug Interactions
Always check the suitability of taking NAC alongside prescribed medications with your Doctor.
NAC is not suitable for use with Metaclopramide, and Nitroglycerine medications.
