Unhealthy habits hurt kids’ bones
Too little milk, sunshine and exercise leading to rise in rickets in
children
The Associated Press
updated 1:37 p.m. MT, Mon., Nov. 26, 2007
WASHINGTON - Too little milk, sunshine and exercise: It is an anti-bone
trifecta. And for some children, shockingly, it is leading to rickets, the
soft-bone scourge of the 19th century.
But cases of full-blown rickets are just the red flag: Bone specialists say
possibly millions of seemingly healthy children in the U.S. are not
building as much strong bone as they should — a gap that may leave them
more vulnerable to bone-cracking osteoporosis later in life than their
grandparents are.
"This potentially is a time-bomb," says Dr. Laura Tosi, bone health chief
at Children's National Medical Center in Washington.
Now scientists are taking the first steps to track childrens' bone quality
and learn just how big a problem the anti-bone trio is causing, thanks to
new research that finally shows just what "normal" bone density is for
children of different ages.
First bone-growth guide
Dr. Heidi Kalkwarf of the Cincinnati Children's Hospital led a U.S. study
that gave bone scans to 1,500 healthy children ages 6 to 17 to see how bone
mass is accumulated. The result, published last summer: The first
bone-growth guide, just like height-and-weight charts, for pediatricians
treating children at high risk of bone problems.
Next, the government-funded study is tracking those 1,500 children for
seven more years, to see how their bones turn out. Say a 7-year-old is in
the 50th percentile for bone growth. Does she tend to stay at that level by
age 14, or catch up to kids with denser bones? If not, if she more prone to
fractures?
Ultimately, the question is what level is cause for concern.
"I don't know if we're raising a population that's going to be at risk" for
osteoporosis, Kalkwarf cautions. "It's really hard to know what the cutoff
is, how low is too low."
But almost half of peak bone mass develops during adolescence, and the
concern is that missing out on the strongest possible bones in childhood
could haunt people decades later. By the 30s, bone is broken down faster
than it is rebuilt. Then it is a race to maintain bone and avoid the thin
bones of osteoporosis in old age.
"There's some early data showing that even a 10 percent deficit in your
bone mass when you finish your adolescent years can increase your potential
risk of having osteoporosis and fractures as much as 50 percent," says Dr.
James Beaty, president of the American Academy of Orthopaedic Surgeons.
Already there's evidence that U.S. children break their arms more often
today than four decades ago — girls 56 percent more, and boys 32 percent
more, according to a Mayo Clinic study.
Kalkwarf's hospital recently found that kids who break an arm have lower
bone density than their playmates who don't. That suggests the fracture
rise isn't due solely to newer forms of risky play, like inline skates.
Fracture risks for overweight
And last year, government researchers found overweight children were more
likely to suffer a fracture, even though theoretically their bones should
be hardier from carrying more weight. Maybe they have poorer balance; maybe
they fall harder. Kalkwarf says there even are hints that fat itself may
produce bone-harming substances.
Doctors have long known that less than a quarter of adolescents get enough
calcium.
But strong bones require more than calcium alone. Exercise is at least as
important. Consider: The dominant arm of a tennis player has 35 percent
more bone than the non-dominant arm.
And Canadian researchers recently reported that postmenopausal women who
had exercised more as teens had 8 percent stronger bone decades later than
their more sedentary counterparts.
Yet childhood exercise is dropping as obesity rises.
Likewise, the body can't absorb calcium and harden bones without vitamin D.
By some estimates, 30 percent of teens get too little.
It is not just that they do not drink fortified milk. Bodies make vitamin D
with sunlight. With teen computer use, urban youngsters without safe places
to play outdoors and less school P.E., it's no wonder D levels are low.
Because skin pigment alters sun absorption, black children are particularly
at risk.
Rickets marks the worst deficiency, where bones become so soft that legs
literally bow. Rickets was once thought to have been eradicated with milk
fortification, but "I am now treating rickets in a way that I never treated
it 20 years ago," says Tosi, who diagnoses rickets or super-low D levels in
children every month at a bone clinic she runs for mostly inner-city
children.
Doctors who have never seen rickets can miss it. Charlene Bullock
repeatedly asked her 5-year-old's doctor why his leg was bending inward and
he could no longer run with his playmates. It took a trip to Tosi's special
clinic to learn Na-shun had rickets — the once energetic child had quit
running because his bones ached like an old man's.
Fortunately, rickets caught early is easily cured with high-dose infusions
of vitamin D and calcium, and Bullock's son quickly rebounded. "He's doing
everything with that little leg."
It is the children whose low vitamin D has not gotten quite bad enough for
symptoms that Tosi most worries about. They may never get treated.
Copyright 2007 The Associated Press. All rights reserved. This material may
not be published, broadcast, rewritten or redistributed.
URL:
http://www.msnbc.msn.com/id/21979043...5773?gt1=10613
Overweight children are more likely to suffer a fracture 
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