Glutathione, the body's master antioxidant and detoxifier, is one of the 14 "Superfoods" listed in SuperFoods Rx : Fourteen Foods That Will Change Your Life, co-authored by Dr Steven Pratt. Glutathione levels cannot be increased to a clinically beneficial extent by orally ingesting a single dose of glutathione. (1) This is because glutathione is manufactured inside the cell, from its precursor amino acids, glycine, glutamate and cystine. Hence food sources or supplements that increase glutathione must either provide the precursors of glutathione, or enhance its production by some other means.