Comparing Protein Restriction and Isoleucine Restriction in Aged Mice

Proteins are made up of amino acids. It is known that reducing only protein in the diet, while maintaining the same calorie intake, produces a modest slowing of aging. Some of the beneficial effects of reduced calorie intake, such as upregulation of autophagy and improved cell maintenance, are triggered by sensing protein levels rather than other components of diet. The sensor mechanisms are more specific than simply protein as a whole, however, and can be triggered by reducing levels of individual essential amino acids, meaning amino acids that are required for protein synthesis in cells, but must be consumed because they are not manufactured in the body. A good deal of work has gone into assessing the effects of lower levels of the essential amino acid methionine in the diet, for example, finding that this captures a sizable fraction of the benefits of reduced calorie intake. In today's open access paper, researchers compare overall protein restriction (all dietary amino acids) with restriction of only the essential amino acid isoleucine, in both cases maintaining an overall calorie intake equivalent to that of a non-restricted diet. Old mice are given these different diets, and the researchers present a great deal of data on the outcomes. Restriction in older individuals doesn't help with muscle loss and frailty, which is interesting given that long-term calorie restriction does slow the progression of age-related loss of muscle mass and strength. Restricting only i...
Source: Fight Aging! - Category: Research Authors: Tags: Medicine, Biotech, Research Source Type: blogs