Cysteine (abbreviated as Cys or C) is a semi-essential proteinogenic amino acid with the formula HO2CCH(NH2)CH2SH>. It is encoded by the codons UGU and UGC.
When used as a food additive, it has the E number E920.
The presence of L-Cysteine is often a point of contention for people following dietary restrictions such as Kosher, Halal, Vegan or Vegetarian as it may be sourced from various human or animal sources. As a result, an increasing amount of L-Cysteine is produced via a microbial or other synthetic processes.
Cysteine has been proposed as a preventative or antidote for some of the negative effects of alcohol, including liver damage and hangover. It counteracts the poisonous effects of acetaldehyde. Cysteine supports the next step in metabolism, which turns acetaldehyde into the relatively harmless acetic acid.
The N-acetyl-cysteine form of cysteine is used in medicine as a way to increase the effectiveness of corticosteroid drugs. It can also be used to decrease the unpleasant symptoms of certain chemotherapy drugs, as a treatment for acetaminophen poisoning and as a way to prevent physiological tolerance to the chest pain medication nitroglycerin.
According to the World’s Healthiest Foods website and Healthy.net, consuming cysteine both in foods and as a dietary supplement has alternative medicine benefits; it is thought to help protect against cellular damage by free radical compounds, eliminate metal ions and potentially harmful chemicals from body tissue and help treat or prevent respiratory problems such as asthma and excessive mucus buildup.
N-acetyl cysteine is LIKELY SAFE for most adults, when used as a prescription medication. It can cause nausea, vomiting, and diarrhea or constipation. Rarely, it can cause rashes, fever, headache, drowsiness, low blood pressure, and liver problems.
When inhaled (breathed into the lungs), it can also cause swelling in the mouth, runny nose, drowsiness, clamminess, and chest tightness.
N-acetyl cysteine has an unpleasant odor that may make it hard to take.
Special Precautions & Warnings:
Pregnancy or breast-feeding: N-acetyl cysteine is POSSIBLY SAFE when taken by mouth, delivered through a hole in the windpipe, or breathed in. N-acetyl cysteine crosses the placenta, but there is no evidence so far linking it with harm to the unborn child or mother. However, N-acetyl cysteine should only be used in pregnant women when clearly needed, such as in cases of acetaminophen toxicity.
There is not enough reliable information about the safety of taking N-acetyl cysteine if you are breast-feeding. Stay on the safe side and avoid use.
Allergy: Don’t use N-acetyl cysteine if you are allergic to acetyl cysteine.
Asthma: There is a concern that N-acetyl cysteine might cause bronchospasm in people with asthma if inhaled or taken by mouth or through a tube in the windpipe. If you take N-acetyl cysteine and have asthma, you should be monitored by your healthcare provider.
Bleeding disorder. N-acetyl cysteine might slow blood clotting. There is concern that N-acetyl cysteine might increase the risk of bruising and bleeding in people with bleeding disorders.
Surgery. N-acetyl cysteine might slow blood clotting. This might increase the risk of bleeding during and after surgery. Stop taking N-acetyl cysteine at least 2 weeks before a scheduled surgery.
Nitroglycerin interacts with N-ACETYL CYSTEINE
Nitroglycerin can dilate blood vessels and increase blood flow. Taking N-acetyl cysteine seems to increase the effects of nitroglycerin. This could cause increased chance of side effects including headache, dizziness, and lightheadedness.
Activated charcoal interacts with N-ACETYL CYSTEINE
Activated charcoal is sometimes used to prevent poisoning in people who take too much acetaminophen and other medications. Activated charcoal can bind up these medications in the stomach and prevent them from being absorbed by the body. Taking N-acetyl cysteine at the same time as activated charcoal might decrease how well it works for preventing poisoning.
Acetyl Cysteine, Acétyl Cystéine, Acetylcysteine, Acétylcystéine, Chlorhydrate de Cystéine, Cysteine, Cystéine, Cysteine Hydrochloride, Cystine, Hydrochlorure de Cystéine, L-Cysteine, L-Cystéine, L-Cysteine HCl, L-Cystéine HCl, NAC, N-Acetil Cisteína, N-Acetyl-B-Cysteine, N-Acétyl Cystéine, N-Acetyl-L-Cysteine, N-Acétyl-L-Cystéine, N-Acetylcysteine, N-Acétylcystéine
Source: WebMD, http://www.webmd.com/vitamins-supplements/ingredientmono-1018-n-acetyl%20cysteine.aspx?activeingredientid=1018