Tag Archives: Cysteine



Posted on 27. Dec, 2010 by .


Cysteine is an amino acid that can be found in many proteins throughout the body. When used as a supplements, it is usually in the form of N-acetyl-L-cysteine (NAC). The body converts this to cysteine and then to glutathione, a powerful antioxidant.

Antioxidants fight free radicals, harmful compounds in the body that damage cell membranes and DNA. Free radicals occur naturally in the body, but environmental toxins (including ultraviolet light, radiation, cigarette smoking, and air pollution) can increase the number of these damaging particles. Free radicals are believed to play a role in aging as well as the development of a number of health problems, including heart disease and cancer.

NAC can help prevent side effects caused by drug reactions and toxic chemicals, and helps break down mucus in the body. It appears to have benefits in treating some respiratory conditions, such as bronchitis and COPD


N-acetyl cysteine (NAC) may be used in preventing or treating the following conditions:

Acetaminophen poisoning

Intravenous (IV) NAC is often given to people who have taken an overdose of acetaminophen (Tylenol), to prevent or reduce liver and kidney damage. Acetaminophen poisoning can also occur at lower doses if someone drinks alcohol or takes certain medications that may damage the liver on a regular basis.


In clinical studies of people 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, the combination can also cause a severe headache. You should not try to treat chest pain on your own; always see a doctor.

Chronic bronchitis and Chronic Obstructive Pulmonary Disease (COPD)

A review of clinical studies found that NAC may help improve symptoms associated with chronic bronchitis, leading to fewer flare ups. However, one large study failed to find any reduction in flare ups among people with chronic bronchitis. In another study of people with moderate to severe COPD, taking NAC decreased the number of flare ups about 40% when used with other therapies.


In one six-month study, people who took 600 mg of NAC twice daily had fewer flu symptoms than those who took placebo.

Acute Respiratory Distress Syndrome (ARDS)

Acute respiratory distress syndrome (ARDS) develops after an injury or trauma to the lungs and is life-threatening. Although not all studies agree, some research (laboratory and human) suggests that intravenous NAC may boost levels of glutathione and help prevent and/or treat lung damage caused by ARDS. However, results of other studies have been conflicting. In one study, giving NAC or Procysteine (a synthetic cysteine) to people with ARDS helped reduce the severity of their condition. But it did not reduce the number of overall deaths compared to placebo.

N-Acetyl Cysteine and the Immune System

Glutathione is known to aid in the transport of nutrients to lymphocytes and phagocytes, two major classes of immune cells, and to protect cell membranes. While purified glutathione is available as a dietary supplement, absorption is low, and N-Acetyl Cysteine is thought to be a better method of boosting cellular glutathione levels. N-Acetyl Cysteine is being investigated as a treatment for AIDS.

N-Acetyl Cysteine Breaks up Mucus

N-Acetyl Cysteine cleaves disulfide bonds by converting them to two sulfhydryl groups. This action results in the breakup of mucoproteins in lung mucus, reducing their chain lengths and thinning the mucus, improving conditions such as bronchitis and flu. Double-blind research has found that N-Acetyl Cysteine supplements improved symptoms and prevented recurrences in people with chronic bronchitis. N-Acetyl Cysteine at a dosage of 1,200 mg per day helps to prevent Influenza infection, reduces the symptoms of existing Influenza infection and reduces the duration of Influenza infections.

N-Acetyl Cysteine and Cancer

N-Acetyl CysteineN-Acetyl Cysteine has been shown to reduce the proliferation of certain cells lining the colon and may reduce the risk of colon cancer in people with recurrent polyps in the colon. Its action as an antioxidant and a glutathione precursor may also contribute to a protective effect against cancer.


Some researchers have investigated whether cysteine can help improve levels of glutathione in people with HIV or AIDS. In one well-designed clinical study of people with HIV, those who took daily supplements 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 more weight after 12 weeks than those who took placebo. Similarly, in a smaller-scale clinical study where HIV positive patients took NAC, the supplement did increase glutathione levels while a placebo did not. Other clinical studies, however, have shown negative results using NAC for those with HIV. More research is needed to see whether NAC has any benefit for people with HIV.

Other Uses

NAC has also been proposed for the following conditions, although evidence is limited:

* Reducing symptoms associated with Sjögren’s syndrome (an autoimmune disorder characterized by dry mouth and dry eyes)
* Reducing symptoms of asthma, cystic fibrosis, and emphysema
* Preventing colon cancer
* Preventing cataracts and macular degeneration
* Helping increase HDL “good” cholesterol
* Helping increase fertility when taken along with fertility drugs in people with polycystic ovary disease
* Helping improve outcome in children with advanced cerebral adrenoleukodystrophy, a type of leukemia
* Helping treat cocaine addiction, schizophrenia, and gambling addiction
* Reducing lung cancer risk among smokers

How NAC (N-Acetyl-Cysteine) Works To Detoxify From Mercury

Mercury Amalgams : “I don’t feel comfortable using a substance designated by the Environmental Protection Agency to be a waste disposal hazard. I can’t throw it in the trash, bury it in the ground, or put it in a landfill, but they say it is OK to put it in people’s mouths. That doesn’t make sense.” – Richard. Fischer, D.D.S.
N-Acetyl-Cysteine is currently the dietary supplement of choice for building up cysteine or conserving the body’s store of Glutathione, Cysteine and other Sulfhydryl anti-oxidant resources. This is very crucial for the body’s life functions, as NAC helps the body neutralize toxins, heavy metals, such as mercury from dental amalgam fillings, cadmium and lead from paint and cigarette smoke.
The Sulfhydryl balance has also been linked to enhance resistance to viral infections.

NAC is a chelator of heavy metals. In other words, NAC binds to toxic heavy metals such as mercury and lead, and removes them from the body. This is a slow process, but most chelating agents, such as EDTA, are generally given intravenously. NAC is one of the most effective oral chelating agents. Taken regularly over a period of time, NAC will remove many toxic heavy metals from the body NAC has been shown to antidote acetaminophen (Tylenol) poisoning, mercury poisoning, and even arsenic poisoning. Mercury is especially important because of the increasing evidence linking mercury amalgam dental fillings with the onset of degenerative diseases such as Multiple Sclerosis. NAC chelates, i.e. “grabs” heavy metals and removes them from the body.

NAC has been shown to be a protective agent in many diseases and conditions in which free radicals play a role. This includes cancer, AIDS, cirrhosis, as well as pollution damage from smoking or other chemicals. Rats given NAC were completely protected against cigarette smoke caused DNA cross-linking.
NAC helps with mercury toxicity and other conditions

Cancer research has shown that NAC dramatically reduces the ability of a tumor to invade surrounding tissue. In one study, NAC decreased the number of metastases by 80% when cancer cells were pretreated with NAC. NAC can be used for colon cancer prevention. A preliminary double-blind placebo-controlled study of NAC enrolled 62 individuals, each of whom had had a polyp removed from the colon. The abnormal growth of polyps is closely associated with the development of colon cancer. In this study, the potential anticancer benefits of NAC treatment were evaluated by taking a biopsy of the rectum. Individuals taking NAC at 800 mg daily for 12 weeks showed more normal cells in the biopsied tissue as compared to those in the placebo group.

Immunologically, NAC greatly enhances T-cell production. In fact, all AIDS patients are deficient in NAC and glutathione. NAC suppresses the replication of HIV in vitro and enhances the ability of certain immune cells to kill pathogens. A double-blind study at Stanford University of 45 people, suggested that NAC may increase levels of CD4+ cells (a type of immune cell) in healthy people and slow CD4+ cell decline in people with HIV. Patient given 3200mg to 8000mg of NAC daily for 6 weeks were roughly twice as likely to survive for 2 years as the subject that did not take NAC.

NAC (N-Acetyl-Cysteine) – a friend to your liver

NAC can help to prevent damage to the liver caused from overuse of acetaminophen (Tylenol). NAC is the standard medical treatment for acetaminophen overdose. It is prudent to take NAC whenever one uses acetaminophen.

NAC is an excellent mucolytic agent. It keeps the membranes of the respiratory system moist, thereby lessening the irritation of dry air, dust, and pollutants. It also helps the immune system to do its job properly in the respiratory tract. NAC is available as a prescription drug for this purpose, but you can buy NAC over the counter for far less money.
More studies are needed.
Dietary Sources:

The body makes 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.
Available Forms:

* NAC aerosol spray (prescription)
* NAC liquid solution (prescription)
* NAC topical solution
* L-cysteine powder
* Cysteine/NAC tablets or capsules

How to Take It:


A child should not take NAC unless under the supervision of a doctor.


Recommended adult doses of NAC vary depending on the health condition being treated.

NAC is given either intravenously or orally in the hospital to treat acetaminophen (Tylenol) poisoning in both children and adults. Acetaminophen poisoning is a medical emergency, and treatment must be started within 8 hours of an overdose.

* For adults 18 years and older with respiratory illness: 200 mg, 2 times daily, for chronic bronchitis. For COPD, 600 mg, 2 times daily, has been used. Acute respiratory distress syndrome is a medical emergency and is treated in the hospital with intravenous NAC as part of a comprehensive treatment regimen.
* For antioxidant protection/general health: Take 500 mg daily to start. The dosage may be increased, with your doctor’s supervision. Someone with HIV/AIDS may be put on a dose as high as 4,000 mg daily. Adding a multivitamin will ensure that you are getting the B vitamins you need when taking NAC.

NAC (N-Acetyl-Cysteine) – Take Plenty Of Vitamin C

N-Acetyl Cysteine is a more stable compound than taking oral cysteine, but as it is metabolized, some N-Acetyl Cysteine may be oxidized and become insoluble. This may form kidney stones. It is therefore recommended that individuals taking NAC take 3 times as much vitamin C when taking NAC to prevent the NAC from being oxydized. Diabetics should consult their physician before using N-Acetyl-Cysteine, since it may have an insulin-blocking effect.


Because of the potential for side effects and interactions with medications, dietary supplements should be taken only under the supervision of a knowledgeable health care provider.

Some forms of cysteine are toxic and should be avoided. These include D-cysteine, D-cystine, and 5-methyl cysteine.

NAC may raise levels of homocysteine, an amino acid that is associated with heart disease. Be sure to have your health care provider check your homocysteine level if you are taking NAC.

Extremely high doses (more than 7 grams) of cysteine may be toxic to human cells and may even lead to death.

Oral NAC may cause nausea, vomiting, and diarrhea.

Intravenous administration of NAC (to treat acetaminophen poisoning) may cause severe allergic reactions, including angioedema (swelling of the soft tissue just beneath the skin including the face, lips, and around the eyes) or anaphylaxis (a life-threatening allergy).

People with cystinuria, a kidney condition in which too much cysteine (along with three other amino acids) is lost in the urine, should not take cysteine supplements.
Possible Interactions:

If you are currently being treated with any of the following medications, you should not use cysteine supplements without first talking to your health care provider.

Angiotensin-converting enzyme (ACE) inhibitors (blood pressure medication) — NAC may increase the blood pressure-lowering effects of ACE inhibitors. Examples of ACE inhibitors include:

* Captopril (Capoten)
* Enlapril (Vasotec)
* Lisinopril (Zestril, Prinivil)
* Fosinopril (Monopril)

Immunosuppressive medications — Treatment with NAC may stregthen the effects of some medications that suppress the immune system, such as azathioprine (Imuran), cyclophosphamide (Cytoxan), or prednisone (Deltasone). Do not take NAC with these medications without talking to your doctor first.

Cisplatin and doxorubicin — Laboratory and animal studies have suggested that NAC may reduce the toxic effects associated with cisplatin (Platinol) and doxorubicin (Ardiamycin). These medications are used to treat a variety of cancers. However, scientific studies are needed to see if this is true in humans.

Nitroglycerin and isosorbide — NAC may strengthen the effect of nitroglycerin and isosorbide (Isordil), two medications commonly used to treat chest pain. But this combination may also increase the risk of side effects such as severe headaches and may lead to abnormally low blood pressure. Do not take NAC with these medications unless your doctor tells you to do so.

Oxiconazole — Topical applications of NAC may strengthen the effect of oxiconazole (Oxistat), an antifungal medication used for athlete’s foot.

Groups at risk of cysteine deficiency

Deficiency of cysteine is rare, but can occur in the following individuals:

* People on low protein diets – people who are not eating enough protein foods may not get enough cysteine in their diet
* Vegans / vegetarians – people who are on a strict vegetarian diet may suffer from a cysteine deficiency if their diet is deficient in protein
* HIV / AIDS patients – People suffering from HIV/AIDS may benefit from cysteine in medically administered dosages, as low levels are normally reported in HIV/AIDS patients

People in these groups at risk of cysteine deficiency should talk to a medical professional about cysteine supplementation BEFORE trying it.

Symptoms of cysteine deficiency

No direct deficiencies have been reported, but in chronic diseases it seems the formation of cysteine from methionine can be prevented, resulting in a deficiency

Cysteine in food

The body can synthesise cysteine from the amino acid methionine, so there is unlikely to be a deficiency in this amino acid. It is also found in high protein foods such as:

* Broccoli
* Eggs
* Garlic
* Onions
* Poultry
* Red peppers
* Wheat

Cysteine works best with

* Folic Acid
* Vitamin B3 (Niacin)
* Vitamin B6 (Pyridoxine)
* Vitamin B12 (Cobalamin)
* Vitamin C
* Chromium
* Glycine
* Glutamine
* Methionine
* Serine

Overdosage, toxicity and cautions for cysteine

None known, but damage to nerve cells in rats has been reported in very high dosage, and research data is still not available.

Alternative Names:

Acetylcysteine; L-cysteine; N-acetylcysteine; NAC

thank you and reference


Continue Reading