Low birth weight children are more likely
to develop cardiovascular problems
David Barker, is an epidemiologist at the University
of Southampton, in England. Barker has long argued that our chances
of developing
heart disease and other chronic ills depend to a surprising degree
on what happens to us early in life - not just as kids but as fetuses.
He reasons that, like a poorly made car, an undernourished fetus
is more likely to break down later. "We've been obsessed with the
breaking-down bit," he says, "and we've forgotten how easy it is
to influence people permanently before they're born. "
Barker and others have amassed considerable evidence that
smaller-than-average babies run a bigger-than-average risk of developing
hypertension, diabetes and heart disease as adults. The possibility first
occurred to him back in the early '80s, as he puzzled over Britain's regional
disease patterns. Heart-disease mortality is twice as high in some areas
as in others, even when dietary and lifestyle differences are taken into
account. Looking back in time, Barker noticed that the heart-attack hot
spots had been infant-mortality hot spots 70 years earlier. Suspecting
that early deprivation might have long-delayed consequences, he gathered
data on 16,000 Britons born between 1911 and 1930. His analysis showed that among people who reached full term and weighed
from 5.5 to 9.5 pounds at birth, those with the lowest birth weights
had the highest average heart-disease rates.
Subsequent studies
have brought mixed results, but most tend to support Barkers hypothesis.
In the past year alone, he and his colleagues have
linked low birth weight to stroke and heart attack in British men, and
to cardiovascular disease in men and women from southern India. Large
studies conducted in Wales and the United States have turned up the same
pattern. When Dr. Gary Curhan of Harvard looked at birth weight and
blood
pressure in 164,000 female nurses, he found that hypertension was 40
percent more common among those born weighing less than 5 pounds than
among those
born at 7 to 8.5 pounds. "It really looks like there's something to this," says
Harvard epidemiologist Walter Willett.
How could low birth weight foster chronic disease? One theory holds that
when a fetus lacks the nutrients it needs, its body resorts to a costly
sort of triage. "The first thing it does is alter its metabolism so it
can continue to grow," says Barker. That could mean ratcheting up its
blood pressure to draw more nutrients through the placenta, or abandoning
work on the liver, pancreas and blood vessels to complete construction
of the brain. When unborn rats or sheep are deprived of nutrients, they
make all these adjustments, and suffer accordingly. Barker draws the lesson
that women can protect their kids against heart disease by eating well
during pregnancy, but many experts are skeptical. A newborn's size is
only modestly related to its mother's diet, says Dr. Nigel Paneth, an
epidemiologist at Michigan State University. And even if low birth weight
does contribute to heart disease, Barkers own studies show that adult
obesity is a stronger predictor.
P. gingivalis is a bug that inflames our gums, and preliminary evidence
suggests that it may also gum up our arteries. As part of the VA Normative
Aging Study, Dr. Raul Garcia of the Boston VA Outpatient Clinic followed
1, 100 men over a 25-year period. They were all basically healthy
at the
outset, but they had varying levels of gum disease. And over the course
of the study, the men with bad gums suffered nearly twice the heart-attack
rate of their fresh-mouthed counterparts - and nearly three times the
stroke rate. The bottom line, as Garcia puts it half jokingly: "Floss
or die. " In truth, no one knows whether P. gingivalis can kill you,
but the bacterium has been found in diseased carotid arteries. Researchers
now hope to see whether treating gum disease can help prevent heart attacks.
Together, these inquiries are painting an ever-richer picture of America's
leading killer. None of the new findings imply that cholesterol doesn't
matter, but they suggest it's not our only enemy -or even our worst one. As the homocysteine revolution unfolds, it may turn out that we can accomplish
more with nickel-and-dime vitamin supplements than with drugs that cost
hundreds of times more. And if the bacterial connections hold up, antibiotics
and dental floss may become major weapons in cardiology. But whatever
happens, the way we eat and live will count as much as ever.
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