http://news.bbc.co.uk/1/hi/health/2167316.stm
BBC News/Health
Friday, 2 August, 2002, 00:19 GMT 01:19 UK
Scientists unravel secrets of long life
By Richard Black
BBC science correspondent
Scientists in the United States have
discovered three things which help predict how
long someone is going to live.
In a study published in the journal Science,
they report that the length of a person's life is
related to their body temperature, and to
levels of two chemicals, insulin and DHEAS,
circulating in the blood.
On average, people
who have a lower
body temperature live
longer, as do those
with lower levels of
insulin, and those with
higher levels of
DHEAS.
The researchers are not entirely sure of
the reasons behind this finding but
experiments with animals suggest it may
be to do with a lower metabolic rate.
They say that unravelling the mechanisms
behind the finding may lead to new ways
of helping people to live longer.
Of mice and men
The suggested link between lifespan and
metabolic rate comes from experiments
in which animals are maintained on strict
calorie-controlled diets.
These animals tend to live longer than
normal - up to 40% longer. They also
have lower than average body
temperature, low levels of insulin, and
high levels of dehydroepiandrosterone
sulphate (DHEAS).
George Roth from the National Institute
of Ageing in Baltimore in the United States
has been working on a long-term study of
factors affecting human lifespan.
Called the Baltimore Longitudinal Study of
Ageing, it has been running since 1958
and has enrolled around 1,500 people.
Longevity clues
Following the lead given by the animal diet
experiments, Dr Roth's team decided to
analyse body temperature and levels of
insulin and DHEAS in men enrolled in the
Baltimore study.
"Men with lower temperature and insulin
and those maintaining higher DHEAS levels
have greater survival than respective
counterparts," he writes in the Science
journal. At present, there are not enough
data to say precisely how big these
effects are.
The average human body temperature is
around 37 degrees Celsius but individuals
differ by around a degree.
The men in the Baltimore study are not
on diets. So something else must be
keeping body temperature and insulin
down, and DHEAS up, in the men who are
living longer.
"It could be genetic, it could be something
else in their lifestyle apart from diet," Dr
Roth told the BBC. "If we can learn what
these individuals are doing then perhaps
we could help the rest of us to live longer,
too."
