Cysteine is necessary for new skin formation, comprising 10 to 14 percent of all skin and hair molecules

Cysteine (or L-cysteine) is one of 22 amino acids commonly referred to as the building blocks of protein. There are two specific types of amino acids: essential amino acids and nonessential amino acids. Typically, they are categorized based on their nutritional role and value within the body. Essential amino acids are those that cannot be produced by the body and as such, must be obtained through either a food source or through supplements. Nonessential amino acids on the other hand, are those that can either be manufactured by the body through a metabolic or physiologic process or through the synthesis of another amino acid within the body. These types of amino acids can also be obtained from dietary sources or supplements. Cysteine is a sulfur-based amino acid and is one of the 11 identified nonessential amino acids. Some people mistakenly believe that because a particular amino acid is classified as ‘nonessential’, it is not necessary to the body; however this is completely untrue. Perhaps scientists should have used different terms when classifying these amino acids, nevertheless their intention was to relate that these nonessential acids are still very important. Ideally, there are other avenues, apart from the body’s own manufacturing process, such as diet, through which they can be obtained. Researchers have since added a third sub-category of nonessential amino acids known as ‘conditionally-essential.’ Basically, these are the amino acids normally formed in our body, but under very specific circumstances, such as disease, injury or in times of extreme stress, the body is unable to produce adequate amounts of these compounds, necessitating the need for supplemental or dietary sources.

Amino acids in general function as antioxidants, protecting the body against harmful free radical production that can alter DNA and other cellular functions. While free radicals are also a natural byproduct of aging, when radiation and other environmental pollutants such as ultraviolet light, noxious chemicals and cigarette smoke are further introduced into the system, the body can become overwhelmed triggering such health problems as heart disease and cancer. Apart from its extraordinary antioxidant properties, cysteine in particular, is also necessary for the formation of new skin cells, an obvious requirement in burn cases or after surgery for example. The hair and skin is composed of 10 to 14 percent cysteine, making this amino acid very important in both the healing and aging process.

N-acetyl-L-cysteine (NAC) is a modified form of the amino acid cysteine and is the form most widely used for nutritional and healing purposes. This particular structure of the amino acid is known to help break up mucus and rid the body of heavy metals. Both cysteine and NAC are also believed to increase metabolic levels of another amino acid called glutathione (GTH). NAC, in conjunction with glutamic acid and glycine, is a key component in the conversion of cysteine into GTH, now known to be the body’s primary cellular antioxidant.

Researchers believe that NAC acts in two principal ways to increase overall cellular health. First, studies show that NAC is quickly and easily metabolized into GTH, a process that triggers antioxidant activities. GTH then synthesizes harmful chemicals into more benign compounds. It is also responsible for reducing and eliminating heavy metals such as mercury and lead, both of which are highly toxic to the body. Further, NAC is known to transport beneficial nutrients to immune cells and protect cellular membranes.

Secondly, through a delicate deconstruction process, NAC has been found to break up mucoprotein cells found in pulmonary mucus, reducing and thinning excess mucus in cases of bronchitis or smoker’s cough. It is this property that has brought NAC to the forefront of several studies on respiratory conditions such as acute respiratory distress syndrome (ARDS), a condition that results in rapid and progressive lung deterioration. It is thought that intravenous NAC may boost levels of GTH preventing and possibly treating lung damage caused by ARDS.

In one study of 116 individuals suffering form chronic bronchitis, it was shown that those who took NAC for 6 months required significantly less sick days while suffering from fewer days of heightened coughing. Further investigations into NAC’s mucolytic properties show that this amino acid derivative may also be helpful in cases of cystic fibrosis, asthma, and emphysema. Researchers are also looking to NAC as an anti-carcinogenic nutrient for those at risk for lung cancer.

Traditionally, one of the most widely recognized uses for NAC is in cases of acetaminophen poisoning. Those admitted to hospital with an acetaminophen overdose are routinely administered intravenous NAC as a means to protect the liver and kidneys from this drug’s toxic side effects. This type of poisoning is quickly becoming a serious health concern for medical professionals who invariably treat hundreds of these cases each year. It is especially common among those who drink alcohol on a regular basis since acetaminophen poisoning can occur from much lower doses in these individuals. Many over-the-counter medications such as cold remedies or pain relievers contain acetaminophen (most commonly as Tylenol) and poisoning occurs primarily when people take several products together, unknowingly digesting unsafe amounts of the drug. Unfortunately, once poisoning occurs there is a high risk of potentially life-threatening complications including liver failure and renal disease and as such, NAC must be administered within 8 hours.

Low levels of GTH are consistently seen in people suffering from a variety of immune disorders including acquired immunodeficiency syndrome (AIDS). Although GTH can be taken in supplemental form, absorption rates are extremely low. NAC therefore is thought to be the better choice for boosting the immune system. In cases of HIV and AIDS, excessive oxidative stress (free radical damage) in conjunction with low GTH levels has been identified as the primary cause. There have been several studies on the subject and in most cases, the introduction of NAC has significantly boosted immune function. In one such study, HIV sufferers who took a daily dose of 40g glutamine, 800 mg vitamin C, 500 IU vitamin E, 27,000 IU beta-carotene, 280 mcg selenium and 2400 mg NAC gained significantly more weight than the placebo group after 12 weeks of supplementation.

In another study, 53 percent of HIV positive patients who received two daily injections of 400 mg NAC or an oral supplementation of 600 mg NAC twice daily, did not progress to an AIDS diagnosis. Of those patients, 25 percent actually became HIV negative. One further study suggests that HIV-positive patients who took NAC were two times as likely to survive an additional two years longer than those not taking the supplement. NAC was shown to boost GTH levels, which in turn boost immune function including T cells, B cells and phagocyte levels, all of which protect the body against secondary complications of the disease such as pneumonia.

NAC is also used in cases of coronary distress. Studies of individuals, who are suffering a heart attack with continued chest pain, show that when NAC is given in combination with nitroglycerin, subsequent chest pain and heart attack greatly improved and the risk of death is lowered. This research concluded that both NAC and nitroglycerin are more useful when used together than either is alone, however individuals can experience severe headaches from this treatment.

NAC studies also show that this amino acid is helpful in heart disease and prevention. It has been shown to lower homocysteine and lipoprotein levels, both of which are commonly associated with increased risk of coronary disease. Through its antioxidant properties NAC may also work to stop the damaging effects of free radical oxidation, a process proven to trigger the production of LDL (bad) cholesterol.

In several studies researchers have shown that NAC may play a role in preventing cancer. Through its antioxidant properties, NAC will fight free radical production, a process directly linked to cancer. It is surmised that NAC may therefore reduce and slow the development of cancerous tissue. One study has also shown that NAC reduces nausea and vomiting caused by chemotherapy. Further research is still needed, although results to date are promising.

Once again the antioxidant properties of NAC also make this amino acid a possible preventative and treatment for cataracts and macular degeneration. Both conditions are linked to free radical damage caused by aging and environment. Researchers believe that by boosting the antioxidant activity in the lens and macula of the eye, NAC could help to delay and or prevent these deteriorations.

Research now shows that those suffering from Parkinson’s disease have significantly reduced brain levels of GTH. It is believed that increasing this amino acid may slow the symptoms of the disease and could also minimize age-related deterioration of the nervous system in general.

It is further believed that multiple sclerosis is linked to low GTH levels resulting from free radical damage. Theoretically, NAC could help protect the nerve cells from oxidation, preventing or slowing the progression of this disease.

Studies continue to investigate the seemingly endless benefits of this amino acid. Some suggest it can improve symptoms of Sjogren’s syndrome, an autoimmune disorder that causes dry mouth and eyes. Low cysteine levels have also been linked to cervical dysplasia, a precancerous change to the uterus. Some research suggests that NAC may enhance overall cognitive functioning in cases of Alzheimer’s disease. Other research suggests that NAC could slow the progressive loss of voluntary muscle control associated with ALS or Lou Gehrig’s disease. It has been used in cases of Hepatitis C and is also proving beneficial for symptoms of the flu.

All disease is caused by oxidation. In fact, no disease can live in an oxygen rich environment. Overall, NAC works to counter free radical damage including that caused by environmental toxins such as mercury, lead, chromium and boron. It has also been shown to attack chloroform, carbon monoxide and alcohol, helping the liver to excrete these poisons without complications. These and other toxins wreak havoc on the body, lowering the immune system, triggering disease and overall weakened health. The antioxidant properties of this amino acid make it invaluable for countless health issues.

NAC is available in several forms. Liquid or spray forms are generally available only by prescription. You can however purchase cysteine/NAC as a supplement, usually in tablet form or as a powder. You can also buy NAC as a topical solution. For the most part, when given in hospital for acetaminophen poisoning, NAC is administered intravenously. It can also be given orally and in both cases is used to treat children and adults. When children are diagnosed with an amino acid imbalance, a complete amino acid regime is normally recommended by the health care professional. For most therapeutic reasons, the typical daily dose of NAC is between 250 to 1500 mg. The adult dose will vary depending on the health problem. Generally however, for cases of respiratory illness such as acute bronchitis, 500 mg three times daily is recommended. For chronic bronchitis most health professionals recommend taking 250 mg three times a day. For sinusitis, take 500 mg twice a day. As an overall antioxidant and for general health, you can take 500 mg daily to start. In some cases, people suffering from AIDS are put on doses as high as 4,000 mg, however you should always consult with a health professional before self-prescribing any supplement, especially is you are already taking prescription medications or other herbs that could interfere or react with each other.
Some forms of cysteine are known to be toxic and should be avoided at all times. These include D-cysteine, D-cystine and 5-methyl cysteine. As well, extremely high doses of 7 grams or more have in some cases caused toxicity and even death. If you have kidney problems or are pregnant speak with your health professional before taking NAC. There are a few reported cases of nausea, vomiting and diarrhea when taking this supplement.
As with all amino acids, NAC is best absorbed when taken between meals, and away from protein foods or supplements. For best absorption, do not take at the same time as other amino acids unless in comprehensive supplement. NAC is more readily absorbed if taken in conjunction with Vitamin B6, Vitamin C and selenium.
NAC is shown to interact with several medications including blood pressure medicines, and ACE inhibitors such as benazepril and captopril. As well, if you are taking any immunosuppressive drugs, NAC can enhance the effectiveness of these medications. NAC has also been shown to increase the effectiveness of nitroglycerin and isosorbide, drugs used to treat chest pain. Studies show NAC can also interfere with oxiconazole, an antifungal medication. If you are currently taking these or any other medications it is best to talk to you health professional before taking NAC.

References:

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