In research funded by BioMarker Pharmaceuticals and the Life Extension Foundation, published in the March 22 2004 online early edition of The Proceedings of the National Academy of Sciences, Steven Spindler PhD and colleagues from the University of California at Riverside found that caloric restriction started late in life prolongs life span in mice.
It had previously been believed that calorie restriction, a proven life-extending therapy that involves lowering calories without inducing malnutrition, must be started in youth to be effective. In the current research, the team found that mice, like fruit flies, that began calorie restriction in late middle-age benefited from it almost immediately.
In the first study, a long-lived strain of mice were fed a control diet or a diet restricted in calories by 40 percent less than normally required by typical mice. The diets were started at nineteen months of age, which is a few months before the onset of age-accelerated death for this species. Mice were checked daily, and autopsies performed upon their deaths. A second experiment fed mice control or calorie restricted diets beginning at seven months of age. At the approximate age of 34 months, gene expression studies of the liver were conducted.
The first study found that within two months of the initiation of the diets, the rate of age-associated mortality decreased three-fold in the restricted group, with the average time to death increasing 42 percent. Maximum lifespan was extended from 37.6 to 43.6 months. The cause of death for both groups of mice was mainly tumors, however the onset and growth of tumors was delayed in the calorie restricted mice.
At the conclusion of the gene expression study, calorie restricted mice showed the same patterns of liver gene expression as mice that began calorie restriction at young ages. In a group of mice that were taken off the restricted diets, 90 percent of this gene expression returned to previous patterns within eight weeks.
Dr Spindler told Life Extension that the findings in this mouse study may be true for humans as well, suggested by this and other studies. He added, “We found that the gene expression changes produced by caloric restriction occur rapidly, and are closely linked with its health benefits. This means we can relatively rapidly screen for pharmaceuticals which reproduce the gene expression effects of caloric restriction in animals, and have a reasonable expectation that these same pharmaceuticals may induce some or all of the beneficial physiological effects of caloric restriction (the delay in cancer mortality, for example), perhaps in humans.” Source: Life Extension Foundation (online at www.lef.org).