Update - It appears some of the key references for this article do not support its contentions. It should therefore be disregarded. The good reports at Amazon are good as far as they go but carry lesser weight. See instead the comment and research by Greenday posted below.
"Acetylglutathione is orally active, unlike plain glutathione, and is stable in the intestine and plasma when absorbed and delivered directly to the cells for natural de-acetylation intracellularly. Plain glutathione delivered to the plasma by precursors, liposomal products or intravenously must be broken down by enzymes to the basic amino acid components for absorption into the cell and require more energy expenditure to be re-constructed back to rGSH. It is known that disease states can block the re-assimilation of components into rGSH. Therefore, it is a better dietary/therapeutic decision to provide the orally active and absorbed Acetylglutathione which increases intracellular rGSH directly and naturally without increased energy expenditure and without being compromised from disease states.,"
Some good reports on this version: