Human dietary supplement linked to longer life in mice

London, England: An over-the-counter supplement designed to ease osteoarthritis prolonged the lifespan of lab mice by nearly a tenth, scientists said Tuesday.

This would translate into an average eight-year longevity gain if the result could be repeated in humans, Swiss researchers reported in the journal Nature Communications.

A team led by Michael Ristow at the Swiss Federal Institute of Technology (ETH) in Zurich used a common dietary supplement called glucosamine on laboratory mice after testing it on worms.

Glucosamine is a naturally occurring compound found in the lubricating fluid which surrounds joints.

It is widely sold over the counter as a supplement to combat osteoarthritis, the commonest form of arthritis, although studies into its efficacy have thrown up mixed results.

Ristow's team first tested a tiny dose on a well-researched lab animal, a nematode worm called Caenorhabditis elegans, and found it extended its lifespan by some five percent.

They then experimented with 146 mice just under two years old -- the rough equivalent of 65 years in human terms.

Mice given glucosamine lived on average 10 percent longer than counterparts who did not get the supplement, which in human terms is about eight years.

Additional work in lab dishes suggested glucosamine had a big effect on the metabolic system, the scientists said.

It prevents the breakdown of large sugar molecules into smaller ones, thus replicating a "low-carb" diet that restricts intake of carbohydrates.

Further work is needed to explain why this appears to affect the mice's longevity -- and to see whether the benefit extends to humans.

"If an even modest effect on ageing were proven, it would be a major advance," Tim Spector, a genetic epidemiologist at King's College London, said in an independent comment.

"However, humans are not the same as worms or rodents, and studies will need careful replication before we get over-excited."

-AFP