When will we see a very-low-methionine diet food range akin to those that exist for brand-name diet fads? The fact that such a thing doesn't exist and isn't being promoted to the hilt is yet another indication that the "anti-aging" marketplace cares little for science. Here's yet more evidence for methionine levels as one of the lynchpins of beneficial changes in metabolism caused by calorie restriction: "Protein or methionine restriction in the diet is known to decrease reactive oxygen species (ROS) production and mitochondrial oxidative stress and to increase maximum longevity in rodents, which could explain how these changes also take place in dietary restriction. However, it is not known whether restriction of other amino acids is also involved. To clarify this question, we studied the effect of restricting all the amino acids, except methionine ... the results obtained in the present study clearly show that the decrease in ingestion of only one molecule, methionine, causes the decrease in ROS production and oxidative damage to mitochondrial DNA that is observed in dietary restriction in relation to the decrease in the rate of aging."

Link: http://www.ncbi.nlm.nih.gov/pubmed/19577342