[PHNUTR-L] Links between smoking and osteoporosis strengthened
Kathrynne Holden, MS, RD
fivestar at nutritionucanlivewith.com
Tue Jun 6 11:10:32 PDT 2006
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Public release date: 5-Jun-2006
Contact: Andrew Leopold
aleopold at webershandwick.com
International Osteoporosis Foundation
Clearing the air – links between smoking and osteoporosis strengthened
Young or old, man or woman, smoker or non-smoker – no matter what
category you fit into, cigarette smoke can weaken your bones and
increase your risk for fractures, according to new research presented
this week at the IOF World Congress on Osteoporosis in Toronto.
Smoking has long been known to increase the risk for osteoporosis in
women, but the new studies, two conducted in Sweden and one in China,
find that smoking also hastens the erosion of men's bones. In addition,
the Chinese study demonstrates, for the first time, that even
second-hand smoke can significantly increase the risk for osteoporosis
and fractures in both men and women.
Bad News from GOOD Study
The deleterious effects of smoking can readily be detected in young
bones. That's one conclusion from the Gothenburg Osteoporosis and
Obesity Determinants (GOOD) study, which has been following the health
of young Swedish men (see conference Abstract No. OC31).
"Though smoking has previously been linked to low bone density in the
elderly population, its effects on adolescents has remained
controversial. Now, we clearly demonstrate that young smokers also have
significant losses in bone density," said Mattias Lorentzon, lead author
on the study.
Lorentzon, working with Prof. Claes Ohlsson and colleagues at the Center
for Bone Research at the Sahlgrenska Academy, Gothenburg University,
measured bone mineral density--a measure of bone strength--in over 1,000
Swedish men between 18 and 20 years old. They found that in smokers,
bone density in the spine, hip, and body as a whole, was lower than in
their non-smoking peers. The most significant effects were in the hip,
where the mineral density was over 5% lower than in
non-smokers--typically, a 10% loss of bone mineral density doubles the
risk of fracture.
Their results explain why previous findings have been equivocal. In this
case the researchers used a sophisticated computer assisted X-ray
machine (CAT scanner) to get three-dimensional images of bone. These 3D
images showed that smoking primarily affects a specific type of bone
called cortical bone. This very dense bone forms a layer, similar to the
enamel on teeth, around softer, spongy bone. Lorentzon and colleagues
found that smoking reduces the thickness of cortical bone. The findings
indicate that smoking may significantly affect bone strength. "If you
think of bone as a pencil, then the thicker the pencil the harder it
will be to break," said Lorentzon.
In a separate study, Center for Bone Research colleagues Dan Mellström
and co-workers have been measuring how a variety of lifestyle and
biological factors influence the likelihood of bone fracture in elderly
men (see conference Abstract No. P117). Mr. OS, as it is called, is
being conducted internationally. Mellström and colleagues have recruited
over 3,000 elderly men for the Swedish part of the study and correlated
smoking history with bone density measurements and fracture incidence.
"We find that in elderly men a history of smoking is associated with
weak bones and almost a twofold increase in vertebral fracture
incidence," said Mellström, who presented the data this week in Toronto.
Vertebral fractures are a major sign of osteoporosis and a strong
predictor of future fractures.
Mellström and colleagues took X-rays of the neck and back spine in over
1,300 men to screen for vertebral fractures--these fractures are often
asymptomatic and go undetected. They found that nearly 17 percent of the
men had an identifiable vertebral fracture, but when they compared
fracture rate to smoking history they found that 24% of smokers had
fractures compared to only 14% or those who never smoked. They also
measured bone mineral density in the hip, thigh bone, and spine.
Mellström reported that bone density in all regions tested was
significantly lower in men who were current smokers, or who used to
smoke. Overall the findings suggest that smoking reduces bone strength
and dramatically increases the risk for bone fractures.
Second-Hand Smoke, First-Hand Problem
In the first ever analysis of the effects of second-hand smoke on bone
density, researchers in the U.S. have found that Chinese men and
pre-menopausal women have significantly lower bone density if they are
exposed to second-hand smoke, even if they are themselves smokers (see
conference Abstract No. P114).
Yu-Hsiang Hsu and colleagues from the Harvard School of Public Health
measured hip bone mineral density in over 14,000 men and women in rural
China--hip fractures are a major cause of morbidity and mortality
worldwide. They also used recorded non-spine fractures and smoking history.
When they correlated smoking with osteoporosis and fracture history,
they found that the largest effects were seen in pre-menopausal,
non-smoking women--only 6% of women in the study were smokers, versus
87% of men. "Compared to non-smokers that are not exposed to second-hand
smoke, premenopausal women exposed to second-hand smoke have a threefold
higher risk of having osteoporosis and a 2.6 times greater risk for a
non-spine fracture," said Hsu. Though smoking itself is a risk factor
for osteoporosis, Hsu and colleagues also deduced that smokers were at
increased risk if they were also exposed to smoke from other family
members on a daily basis.
Though this is the first reported study of the effects of second-hand
smoke on bone health, previous studies have reported that second-hand
smoke may alter levels of estrogen, which is a key hormone for bone
health in both women and men, Hsu explained. "Our finding is consistent
with this hypothesis," said Hsu, who now plans a follow up study to
correlate serum levels of cotinine, a nicotine derivative that only
appears in blood of those exposed to tobacco smoke, with serum hormone
Kathrynne Holden, MS, RD < fivestar at nutritionucanlivewith.com >
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