Glutathione is a substance made from the amino acids glycine, cysteine, and glutamic acid. It is produced by the liver and is involved in many body processes, including tissue building and repair, making chemicals and proteins needed in the body, and immune system function. Glutathione is an antioxidant in plants, animals, fungi, and some bacteria and archaea. It is capable of preventing damage to important cellular components caused by sources such as reactive oxygen species, free radicals, peroxides, and lipid. Glutathione exists in reduced (GSH) and oxidized (GSSG) states, and the ratio of reduced glutathione to oxidized glutathione within cells is a measure of cellular oxidative stress where increased GSSG-to-GSH ratio is indicative of greater oxidative stress.

People take glutathione for various conditions, including aging, alcohol use disorder, liver disease, heart disease, nerve damage caused by the drug cisplatin, and weakened immune systems or infertility, among others. However, there is no good scientific evidence to support most of these uses. Glutathione has been evaluated by the FDA for AIDS-related weight loss, and it has shown benefit among cystic fibrosis and AIDS patients who have decreased glutathione in the intestine.

Glutathione is a powerful antioxidant that may help protect the body from disease, slow cancer progression, and improve insulin sensitivity, among other benefits. It has many important functions, including making DNA, supporting immune function, forming sperm cells, breaking down some free radicals, helping certain enzymes function, regenerating vitamins C and E, transporting mercury out of the brain, and helping the liver and gallbladder deal with fats. While supplements may be appropriate for some people, they may not be safe for everyone, and they could interact with other medications a person is taking. It is important to speak with a doctor before starting glutathione supplementation to determine if it is appropriate for you.