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Male patient discussing the use of cysteine supplements.
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Cysteine is a type of amino acid that's combined in your body with glutamic acid and glycine to make glutathione. Glutathione is a type of protein. Both cysteine and glutathione are available in various supplement forms and are taken for a variety of health purposes, ranging from providing antioxidant effects to correcting a deficiency. Before you begin taking glutathione or cysteine supplements, consult your doctor to discuss the possible risks and proper dosage.


Cysteine is considered a "nonessential" amino acid, meaning that your body can create it and you don't need to get it from your diet, according to the University of Michigan Health System. Cysteine is unique among amino acids in that it contains sulfur, which helps it to maintain protein structure in your body. Also, cysteine is necessary in your body's production of glutathione and the amino acid taurine. The protein glutathione plays an important role as an antioxidant in your body's defense system, according to the University of Pittsburgh Medical Center. Glutathione fights damaging free radicals, mostly in your liver, and can combat toxins like heavy metals and chemicals. Both glutathione and cysteine play parts in your body's defenses and immune-system function.


Cysteine and glutathione supplements are most often used to treat specific deficiencies of these substances, according to the University of Michigan Health System. People who have HIV/AIDS are likely to have low blood levels of cysteine and glutathione. Glutathione deficiencies are sometimes associated with diabetes, male infertility, cancer, cataracts, liver disease, respiratory distress syndrome and idiopathic pulmonary fibrosis. Talk with your healthcare provider before taking cysteine or glutathione.


In addition to correcting deficiencies, glutathione and cysteine supplements are also sometimes recommended for their antioxidant benefits, as well as to help in the treatment of colon cancer, says the University of Michigan Health System. Cysteine supplements are associated with no specific medical conditions, but the modified form known as N-acetyl cysteine, or NAC, has potential benefits for many different ailments. NAC could possibly help people who have angina, chronic bronchitis, cocaine and gambling addictions, chronic blepharitis, Sjogren's syndrome, schizophrenia, liver failure and female infertility due to polycystic ovary syndrome, according to the University of Pittsburgh Medical Center. NAC might also help in preventing influenza, colon cancer and kidney damage due to contrast agents, as well as support chemotherapy cancer treatment. No conclusive, widely accepted scientific evidence supports the use of glutathione, cysteine or NAC supplements for any medical purpose, however.


Your body makes cysteine from methionine and other amino-acid building blocks, and you also get small amounts of the substance from eating high-protein foods, says the University of Michigan Health System. Glutathione is also found in protein-rich foods like fish, meats and walnuts, as well as other food sources like fruits and vegetables, particularly avocados and asparagus. Glutathione is also available in supplement form. Although cysteine is also found as a supplement, it's most commonly found in the form of NAC, notes the University of Pittsburgh Medical Center.


No significant side effects or health dangers are associated with taking cysteine or glutathione supplements, according to the University of Michigan Health System. But the NAC form of cysteine could cause an adverse interaction with nitroglycerin, warns the University of Pittsburgh Medical Center. Also, oral supplements of glutathione appear not to absorb in the human body, further hampering the veracity of health-related benefits.

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