Methionine Restriction and QOD Feeding
The latest issue of Rejuvenation Research is online. You'll find a few more esoteric items on calorie restriction biochemistry, but one paper on methionine restriction is more accessible and interesting. By way of a reminder, recall that there's a fairly good argument for the beneficial effects of calorie restriction to largely stem from lowering the intake of methionine, one of the eight essential amino acids in your diet.Various manipulations of diets in animal models should provide us with more information about aging mechanisms, as research designs become more sophisticated to tease out effective manipulations, and as collection and analysis of animal response data delves more deeply into the actual molecular mechanisms that are altered.
On Methionine Restriction, Suppression of Mitochondrial Dysfunction and Aging
Rats and mice, when subjected to methionine restriction (MetR), may live longer with beneficial changes to their mitochondria. Most explanations of these observations have centered on MetR somehow suppressing the effects of oxygen free radicals.
The other paper that caught my attention is a nice demonstration that the benefits of calorie restriction don't necessarily have anything to do with insulin-like growth factor 1, IGF-1. For those who have been following research into IGF-1 metabolism and aging, a field with at least as much interest as investigations into mitochondria and aging, that might be a counterintuitive result.It is known that dietary restriction (DR) increases maximum longevity in rodents, but the mechanisms involved remain unknown. Among the possible mechanisms, several lines of evidence support the idea that decreases in mitochondrial oxidative stress and in insulin signaling are involved but it is not known if they are interconnected._FightingAging
It has been reported that when C57BL/6 mice are maintained on an every other day (EOD) feeding their overall food intake is only slightly decreased and plasma insulin-like growth factor (IGF)-1 is even somewhat increased. In spite of this, their maximum longevity is increased, analogously to what occurs in classic DR. Thus, this model dissociates the increase in longevity from the decrease in IGF-1 observed in classic DR.
These results support the possibility that EOD DR increases maximum life span at least in part through decreases in mitochondrial oxidative stress which are independent from insulin/IGF-1-like signaling.