The oral diabetes drug metformin may slow the aging process by mimicking the effects of a calorie-restricted diet, according to a new animal study from the United Kingdom. Metformin is believed to be the most commonly prescribed diabetes medicine in the world, with over 48 million prescriptions written in 2010 in the United States alone.
Calorie restriction has been shown, in some cases, to improve health and lengthen life in animals ranging from worms to rhesus monkeys. Similar effects have been noted with the use of metformin, but it has not been clear how the drug might help delay the aging process.
To determine how metformin slows aging, researchers looked at the effects of the medicine on C. elegans worms that were exposed to and colonized by E. coli bacteria — the relationship between these two organisms is similar to that which humans have with healthful bacteria in their gut. (Studies have found that “good” gut bacteria help their host digest and extract nutrients from food, and defects in these bacteria have been linked to metabolic conditions such as Type 2 diabetes and obesity.)
The results showed that the worms lived longer only when the E. coli strain they had been cultured with was sensitive to metformin. In these cases, the worms lived an average of six days longer than usual, equivalent to a third of their normal lifespan.
The researchers discovered that metformin slowed the aging process by altering the metabolism of the E. coli bacteria — specifically, by disrupting the bacteria’s ability to metabolize folate, a type of B vitamin, and methionine, a building block of protein — thereby limiting the nutrients available to the worm, mimicking the effects of a calorie-restricted diet.
When the team added excess sugar to the worms’ diets, however, the life-extending benefits of metformin were cancelled out, a finding that could be particularly relevant for determining how the medicine works in humans.
“We don’t know from this study whether metformin has any effect on human aging. 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,” noted David Gems, PhD, who directed the research.
In a related study, this one conducted at the University of Montreal, investigators found that metformin may slow the aging process and cancer progression by reducing the production of inflammatory cytokines, a component of the immune system that helps fight infection. (When cytokines are overproduced, it leads to chronic inflammation that is involved in both the aging and cancer processes.) Specifically, metformin disrupted a protein that would typically trigger activation of the immune system.
To learn more about the research looking at metformin and C. elegans, read the article “How Diabetes Drug Delays Aging in Worms” or see the study’s abstract in the journal Cell. And to learn more about metformin, click here.