Hi, Alexa.
As Alex has noted, the response to Immunocal has varied. For people who tolerate it well, I think it can be a good source of balanced protein as well as a supplier of cystine. Note that I wrote cystine, not cysteine. In spite of advertising material that may be contrary to this, Immunocal is a whey protein isolate. As such, it is a byproduct of cheese manufacturing, and the whey has been subjected to pasteurization and acid treatment, which denatures proteins and oxidizes cysteine to cystine. The liver absorbs cysteine well, but not cystine, which must be absorbed and processed primarily by the kidneys. Since the liver is normally the main producer of glutathione in the body, and cysteine is usually the rate-limiting amino acid for the synthesis of glutathione, the glutathione production can be helped more by the use of nondenatured whey protein products. Some of them are ImmunePro, RenewPro, True Whey, and the Whey to Health. There may be others. The key words to look for are nondenatured, whey protein concentrate, immunoglobulins, and lactoferrin.
I should note that Freddd, on these forums, has reported that any supplements that have provided glutathione or the substrates for making glutathione have set him back seriously. However, this is not the experience of everyone, and I think it depends on genomic inheritance.
Best regards,
Rich