To live longer - eat less!

Scientists have known for a long time that animals fed diets which border on starvation live longer, but they are now saying that a particular gene is linked to calorie restriction.

In the 1930's it was found that laboratory animals fed a calorie-restricted diet lived longer and had a lower risk of cancer, diabetes and cardiovascular disease, but until now, there has been little evidence to suggest that calorie restriction diets extended human lives.

Researchers at the Salk Institute for Biological Studies in La Jolla, California, have identified a gene in roundworms that directly links calorie restriction to a longer lifespan.

The research team led by Andrew Dillin say a gene called pha-4 plays a role in gut development in embryonic worms, but in adults is associated with calorie-restricted longevity.

However Mr Dillin also says it is unclear whether similar genes may play a similar role in humans but humans do have three genes very similar to the worm's pha-4.

These genes say the researchers are related to glucagon, a pancreatic hormone that increases blood sugar concentration and maintains the body's energy balance, particularly during fasting.

The researchers say the pinpointing of the worm gene might lead to drugs being developed that imitate the effects of calorie restriction and could allow people to live longer without following a severely restrictive diet.

Mr Dillin says whether dietary restriction will increase longevity in humans is unclear but they are now testing the diets on monkeys.

As Mr Dillin says some people are actively doing this voluntarily; he says it usually takes a 50 to 70 per cent reduction in normal food intake to yield longer lifespan in animals but if food is reduced too much and leaning towards starvation that would make life shorter.

Dietary restriction says Mr Dillon is one of the universal forms of increasing longevity and this has been shown in everything ranging from yeast all the way up to dogs.

The report is published in the current issue of the journal Nature.