Releases Saturday 22 November 2003
No 7425 Volume 327
Please remember to credit the BMJ as source when publicising
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(1) EFFECT OF BREAST FEEDING ON BLOOD
PRESSURE MAY BE OVERESTIMATED
(2) SUN AVOIDANCE WILL NOT REDUCE CANCER
(3)
HEARING PROBLEMS MAY BE PROGRAMMED
AT
BIRTH
(1) EFFECT OF
BREAST FEEDING ON BLOOD
PRESSURE MAY BE OVERESTIMATED
(Effect of breast feeding in infancy
on blood pressure in
later life: systematic review and
met-analysis )
http://bmj.com/cgi/content/full/327/7425/1189
Previous research may have overestimated
the beneficial
effects of breast feeding on blood pressure
in later life,
say researchers in this week's BMJ.
Christopher Owen and colleagues reviewed
24 studies
to determine whether breast feeding in
infancy was
associated with lower blood pressure at
different ages
compared with bottle feeding formula milk.
Studies that reported noticeable and statistically
significant differences in blood pressure
between feeding
groups were mostly small, raising the
possibility of
publication bias.
Larger studies showed little difference,
suggesting that
any effect of breast feeding on blood
pressure is, at
most, modest and of limited clinical or
public health
importance, say the authors.
However, breast feeding should be encouraged
on the
basis of other short and long term benefits,
including
improved neural and psychological development,
potential protection against obesity and
allergic disease,
and lower blood cholesterol levels in
later life, they
conclude.
Contact:
Christopher Owen, Epidemiologist, Department
of
Public Health Sciences, St George's Hospital
Medical
School, London, UK
Email: c.owen{at}sghms.ac.uk
(2) SUN AVOIDANCE WILL NOT REDUCE CANCER
(Letter: Sun avoidance will increase
incidence of cancers
overall)
http://bmj.com/cgi/content/full/327/7425/1228
Avoiding the sun is not the best strategy
for reducing
overall rates of cancer, claims a senior
doctor in a letter
to this week's BMJ. Recommending moderate
exposure
to the sun would be more prudent.
Sun exposure is the main source of vitamin
D, which
reduces the risk of colon, breast, prostate,
and other
cancers, writes Professor Cedric Garland
at the
University of California.
People in the United Kingdom cannot synthesise
vitamin
D from November to March, so become deficient
by
December, he says. Therefore, supplementation
of the
diet with vitamin D would be helpful,
in addition to
encouraging moderate exposure to the sun.
Residents of the United Kingdom should
aim for 10-15
minutes a day in the sun when the weather
allows,
without sunscreen, to allow adequate synthesis
of vitamin
D, he concludes.
Contact:
Professor Cedric Garland, University of
California at
San Diego, School of Medicine, La Jolla,
California,
USA
Email: cgarland{at}ucsd.edu
(3) HEARING PROBLEMS
MAY BE PROGRAMMED
AT BIRTH
(The thrifty phenotype hypothesis
and hearing problems)
http://bmj.com/cgi/content/full/327/7425/1199
Hearing loss in adulthood may be programmed
at birth,
and short people may be particularly susceptible,
say
researchers from Sweden in this week's
BMJ.
Their conclusions are based on the theory
(known as the
thrifty phenotype hypothesis) that events
before birth,
such as malnutrition or exposure to alcohol
or nicotine,
may cause disease in adulthood.
They assessed the hearing of 479 men aged
20 to 64,
who were exposed to noise in their jobs,
and 500
randomly selected male conscripts born
in 1974. Factors
such as height, weight, exposure to noise,
heredity for
hearing loss, and other medical disorders
including use of
drugs were taken into account.
Among the conscripts, shortness was found
twice as
often in those with hearing loss as in
men with normal
hearing. Shortness was also associated
with a positive
heredity for hearing loss but not with
noise exposure.
Short workers had worse hearing than expected
by age,
three times more often than taller workers
and were 12
times more often taking drugs.
The thrifty phenotype hypothesis is applicable
to hearing
loss, say the authors. They suggest that
a low level of
growth hormone (IGF-1) before birth leads
to a reduced
number of cells at birth, which results
in short stature and
earlier onset of age related disorders.
Contact:
Marie-Louise Barrenas, Associate Professor
of
Otorhinolaryngology, Goteborg Pediatric
Growth
Research Centre, Goteborg University,
Sweden
Email: marie-louise.barrenas{at}vgregion.se
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London WC1H 9JR
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Association for the
Advancement of Science
(http://www.eurekalert.org)
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