Scientists from the University of Aberdeen, the Aberdeen-based Rowett Research Institute and the Medical Research Council (MRC) in Cambridge have made a major breakthrough in understanding how metabolism affects lifespan.
In a seven-year study of mice they found that those with the highest metabolic rate lived the longest, raising the prospect that the effect could be mimicked in humans.
Scientists have long thought that a high metabolic rate was linked to a shortened life-span. The present discovery turns this century old belief on its head and changes dramatically our understanding of the regulation of life-span.
Metabolism is the series of chemical changes necessary for the maintenance of life which take place inside the cells of the body. It is the means by which nutrients are broken down to smaller building blocks and chemical energy, which are used to make new body materials and to do work.
The researchers discovered that the most metabolically active 25% of the mice studied, far from having shorter life-spans, in fact lived 36% longer than the least active. If the same effects are mimicked in humans then the finding would imply that a higher metabolic rate could add an extra 27 years to the average human lifespan.
When the muscles of the most metabolically active mice were examined, they were found to contain factors that increased their metabolism by making it less efficient.
Although the scientists do not yet fully understand how these factors work, it is suspected that while they make the metabolism less efficient, on the positive side they reduce the generation of toxic by-products called "oxygen free radicals".
Free radicals can cause damage to the genetic information held in cells, but if fewer of them are produced, less cellular damage will take place, enabling the mice to live longer.
Professor John Speakman, leader of the Aberdeen research team, said: "We are really excited by this finding. Exactly how energy metabolism is linked to lifespan has been an issue of debate for decades.