Influence of methionine availability on glutathione synthesis and delivery by the liver

The aim of this study was to define dietary conditions liable to elevate the circulating and tissue levels of glutathione (GSH). For this purpose, GSH synthesis and availability have been compared after supplementation of a low protein diet (10% casein) with 0.6% methionine or after adaptation to a high protein diet (30% casein), the final dietary methionine levels were similar in both cases. To compare the effects of an acute addition of sulfur amino acids to the diet with long-term adaptative changes on GSH status, rats adapted to the 10% casein diet received as a final meal (i) the diet supplemented with 0.6% methionine or (ii) a 30% casein diet.