Methionine Restriction Differs From Calorie Restriction
While methionine restriction brings similar longevity and health benefits to calorie restriction where it has been tested, it doesn't appear to be quite the same thing under the hood - probably meaning the calorie restriction operates through additional mechanisms beyond a reduction in methionine intake: "Life span can be extended in rodents by restricting food availability (caloric restriction [CR]) or by providing food low in methionine (Meth-R). Here, we show that a period of food restriction limited to the first 20 days of life, via a 50% enlargement of litter size, shows extended median and maximal life span relative to mice from normal sized litters and that a Meth-R diet initiated at 12 months of age also significantly increases longevity. Furthermore, mice exposed to a CR diet show changes in liver [biochemistry, including gene expression patterns] that are not observed in liver from age-matched Meth-R mice. These results [suggest] that the spectrum of metabolic changes induced by low-calorie and low-methionine diets may differ in instructive ways." This is also a helpful reminder that starting calorie restriction later in life isn't a waste, and can still provide significant health benefits.
Link: http://biomedgerontology.oxfordjournals.org/cgi/content/full/glp051