Liver key to extending life

Liver key to extending life

Monday, 18 March 2002
An Australian expert argues that the liver is a neglected key in
anti-ageing research.
Liver blood vessell walls

in blood vessel walls deplete: Sample A is from the blood vessel of the
liver of a young rat; Sample B is from an old rat and has few holes.
(Pic: D. Le Couteur)

Professor David Le Couteur, of the Centre for Education and Research
in Ageing at Concord Hospital, presented his case at a symposium at
Sydney University on Saturday.

There are many wonderful things about getting older, said
Dr Le Couteur, a geriatrician with a background in clinical
pharmacology and toxicology.

"Your mortgage is paid off, your children have moved out, you’re not
embarrassed about who you are, and you have the benefit of wisdom and
resilience," he said.

"It would be fine if it wasn’t for dementia, arthritis, heart
disease, cancer, and pneumonia. This is why we are actively
investigating new ways to prevent age-related disease."

Professor Le Couteur said that many age-related illnesses were
caused by toxins and fats and that this is where his interest in the
liver came from.

The liver’s role in the body is to process blood coming from the gut
by absorbing nutrients, metabolising fats, and processing toxins.

"Previous to our research, the liver was not thought to change much
during ageing, except for shrinking in size," he said.

However Professor Le Couteur and colleague Allan McLean of the
National Ageing Research Institute in Melbourne have discovered that as
the liver ages, its blood vessels also change.

The blood vessels in a healthy liver have tiny holes in their walls
to allow blood going from the gut into the liver to be processed.

Professor Le Couteur and team have found that in rats, baboons, and
humans these tiny holes seem to clog up or disappear as the liver ages.

"This means that fats and toxins can’t get processed properly," he
said. "And it explains a lot of problems."

For example, he said, the fats involved in atherosclerosis — the
build-up on blood vessel walls — float around in the blood because they
are unable to be processed properly in the liver.

In an article due to appear in medical journal The Lancet
next month, Professor Le Couteur argues that the age-related increase
in atherosclerosis is due to these age-related changes in the liver.

Previous research has shown that toxins
such as alcohol and
bacteria-derived toxins damage the holes in the blood vessels
but this
is the first time this type of process has been related to diseases of

"Rather than simply using drugs to treat Alzheimer’s and heart
disease, we could be using a broader range of interventions targeted at
the liver instead," Professor Le Couteur said.

His team is exploring avenues such as reducing food intake, using
antioxidants designed to work specifically in the liver at time of
digestion, improving blood flow to the liver, and using substances that
return the healthy holes in liver blood vessels.

Interestingly, alcohol is one such substance that helps to punch
holes in the liver blood vessels — which could explain the so-called
‘wine paradox’. Alcohol in moderation is beneficial to health but too
much is bad.

Professor Le Couteur’s research has been mainly funded by the
National Health and Medical Research Council.

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