Can Cutting Carbohydrates From Your Diet Make You Live Longer?

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It’s an extraordinary
claim. But scientists say you can extend your life AND stay fit
throughout old age – just by a change of diet that switches on your
youth gene…

For centuries
man has dreamed of being immortal, fixated on tales of magic fountains
that restore youth, the rejuvenating power of a vampire’s bite
or asses’ milk.

More recently
came claims that injections of monkey glands or hormone supplements
would make us live longer.

But so far,
what’s actually worked are medical advances such as vaccines
and better living conditions. Over the past century these have boosted
average life expectancy by far more than 50 per cent, from 50 to
88.

The problem
is that this longevity does not mean a healthier life. Indeed, thanks
to chronic diseases such as diabetes and arthritis, we’re becoming
like the Struldbruggs – the miserable characters in Gulliver’s
Travels who were immortal, but still suffered from all the diseases
of old age.

Gradually they
lost their teeth, their hair, their sense of smell and taste. All
their diseases got worse and their memory faded, so they had no
idea who their friends and relations were. At funerals they wept
because they couldn’t die.

But now a U.S.
geneticist is thought to have discovered the secret to a long life,
full of health and energy. And the answer might be as simple as
cutting down on carbohydrates.

Professor Cynthia
Kenyon, whom many experts believe should win the Nobel Prize for
her research into ageing, has discovered that the carbohydrates
we eat – from bananas and potatoes to bread, pasta, biscuits
and cakes – directly affect two key genes that govern youthfulness
and longevity.

She made her
remarkable breakthrough after studying roundworms, specifically
the C.elegans, a worm just a millimetre in size that lives in soil
in temperate climates all over the world.

By tweaking
some of their genes she has been able to help these worms live up
to six times longer than normal. ‘Not only that, but we also
know how to make them stay healthy all that time as well,’
she told an audience at the Wellcome Collection in London earlier
this month.

So, what do
worms have to do with us?

A great deal,
it seems. Professor Kenyon’s work has been successfully repeated
in labs around the world – the genes she found controlling
ageing in worms do the same thing in rats and mice, probably monkeys,
and there are signs they are active in humans, too.

This work has
revolutionised our understanding of ageing, explains Jeff Holly,
professor of clinical sciences at Bristol University.

‘Ten years
ago we thought ageing was probably the result of a slow decay, a
sort of rusting,’ he says. ‘But Professor Kenyon has shown
that it’s not about wear and tear, but instead it is controlled
by genes. That opens the possibility of slowing it down with drugs.’

So how does
a worm hold the key to human ageing?

At 18 days
old the average roundworm is flabby, sluggish and wrinkled. Two
days later it will probably be dead.

However, Professor
Kenyon, based at the University of California, San Francisco, found
that damping down the activity of just one of their genes had a
dramatic effect.

‘Instead
of dying at about 20 days, our first set of mutant worms carried
on living to more than 40 days,’ she says.

‘And they
weren’t sluggish and worn out – they behaved like youngsters.
It was a real shock. In human terms it was the equivalent of talking
to someone you thought was about 30 and finding they were actually
60.’

With more sophisticated
genetic manipulation, she now has some worms that have lived for
an astonishing 144 days. An increase of that proportion would allow
humans to live to 450.

Scientists
already knew how to make laboratory animals live longer and healthier
lives – you just cut back their calories to about three-quarters
of their normal amount.

It’s not
a practical solution for humans, because you feel cold and hungry
all the time.

But what Professor
Kenyon found out was why – drastically reducing calories has
such a remarkable effect.

She discovered
that it changed the way two crucial genes behaved. It turned down
the gene that controls insulin, which in turn switched on another
gene, which acted like an elixir of life.

Read
the rest of the article

October
28, 2010

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