Deciding on a GRS Ultra product for supplementing glutathione greatly depends on the reason why you want to supplement glutathione. Are your needs long term or short term? How important is cost? Are you interested in better athletic performance, general wellness, or support for a treatment such as chemotherapy or radiation? Ideally, the type of glutathione supplementation you choose should be safe, affordable and there should be clinical evidence that it actually is effective at increasing cellular glutathione levels in humans. Glutathione does its work inside the cells of the body, so a supplement should increase glutathione at the cellular level.

Many products can be eliminated from consideration because clinical evidence indicates that they do not work. Glutathione in capsule or tablet form is very common. However, many professionals feel that oral administration of glutathione is ineffective, commonly citing the studies done at the University of Bern and Emory University. One study demonstrated that rats are able to absorb oral glutathione. This goes to show that animal studies alone are not necessarily a reliable guide.

When glutathione is taken orally, very little reaches the bloodstream. There are other products that are probably more effective at delivering glutathione to the bloodstream. There are nasal, sublingual (under the tongue), dermal (patches), and even intravenous administrations. One oral product encloses reduced glutathione in microscopic packages called liposomes. There is not a great deal of clinical evidence that any of these methods increase cellular levels of glutathione. Even if that were the case, the long term use of a direct delivery method might pose problems. The body already has a complex system for managing glutathione involving production, recycling and a two stage negative feedback loop for regulating cellular glutathione levels. Forcing glutathione into the body is likely to disrupt the balance of this system.

Availability of the amino acid cysteine can limit the body's production of glutathione. Therefore, the two most popular ways of making cysteine available for glutathione production are N-acetyl cysteine (also called NAC) and whey protein concentrate. Other compounds that are known to increase levels of glutathione include S-adenosylmethionine, alpha lipoic acid and silymarin or milk thistle. There are products that use combinations of these compounds. They generally include a cysteine donor such as NAC or whey protein in conjunction with the other compounds so as to provide support for all phases of glutathione metabolism.