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Study first to show how metformin extends lifespan in animals

A study published earlier this month in the journal Cell has revealed how the widely prescribed type 2 diabetes drug metformin delays the ageing process in animals.
Researchers from the Institute of Healthy Ageing at University College London looked at the effects of metformin on worms that were grown in the presence of E. coli bacteria, a relationship similar to that humans have with the ‘healthy’ bacteria in our gut.
They found that treatment with metformin extended the life of a worm by up to six days (equivalent to around a third of its normal lifespan).
The team used strains of E. coli with defects in genes are linked to metabolism and tweaked the levels of nutrients available to tease out which metabolic pathways might be affected by the drug.
They found that metformin disrupted the bacteria’s ability to metabolise folate, a type of B-vitami, and methionine, one of the building blocks of proteins. This limits the nutrients that are available to the worm and mimics the effects of dieting to slow down their ageing process.
“Metformin seems to work by altering metabolism in the bacteria that live in the worm, which in turn limits the nutrients that are available to the worm host and has a similar effect to dietary restrictio,” explained lead researcher Dr Filipe Cabreiro.
But the team also found that adding an excess of sugar to the diet cancelled out the life-extending effects of metformin, a finding which they said is particularly relevant for understanding how the drug works in people.
Study director Professor David Gems said: “We don’t know from this study whether metformin has any effect on human ageing.
“The more interesting finding is the suggestion that drugs that alter bacteria in the gut could give us a new way of treating or preventing metabolic diseases like obesity and diabetes .”
The research was supported by the Wellcome Trust and the Medical Research Council.

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