Low calorie diet and longer life span linked by hormone
The hormone that could be responsible for prolonging life of animals fed on a low-calorie diet has been identified using genetically modified mice. The findings open up the possibility of new life-extending medicines and bring scientists a step closer to understanding the link between diet and a long and healthy life.
In experiments using species ranging from worms to primates, scientists have found that a calorie-restricted but nutritionally-balanced diet can prolong life. The phenomenon has puzzled researchers since it was first observed in 1934, when it was found that mice could live twice as long as usual.
Diet is known to have many effects on the body. Many of these are believed to be mediated by hormones, such as fibroblast growth factor-21 (FGF21), which is secreted by the liver in mice during periods of starvation. To investigate whether FGF21 and prolonged life were linked, researchers genetically modified mice to continuously over-produce the hormone. They found that high levels of FGF21 allowed the mice to live on average 10 months longer than their unmodified relatives (38 months vs 28 months). Despite eating a normal diet, the extension in lifespan of the modified mice was equal to that of the mice fed a restricted diet in earlier experiments. This suggests that it could be the release of FGF21 in mice fed a low-calorie diet that is responsible for an extended life. In support of this, the researchers found the same changes in gene activity in the livers of both the GM mice with too much FGF21 and those given a restricted diet.
The researchers found FGF21 caused changes in insulin production and other metabolic processes that could shed further light on the long-life phenomenon, but many more experiments will be needed to understand all the effects of FGF21.