Oh baby, is that where hypertension starts?
Infants who prefer salty foods have higher blood pressure. "Can
a tendency for high blood pressure be traced to infancy?
A new study has found that babies who don't mind the taste of salt have higher blood
pressure than infants who can't stand the stuff.
The researchers believe this early response to salt could indicate which babies
might go on to develop hypertension, or high blood pressure. Here's the reasoning:
a preference for salt in infancy could indicate salt sensitivity, a condition in
which salt in the diet is a major factor in hypertension.
The link was made stronger because babies who had at least one grandparent with
hypertension had the highest blood pressure readings of all, according to the study.
The researchers admit they're still a long way from being able to detect in infancy
who's going to get high blood pressure. But ultimately, that's the goal, says Dr.
Stephen Zinner, lead author of the study and chairman of medicine at Harvard Medical
School in Boston.
"It's possible the tendency for hypertension might be predictable early in life,"
Zinner says. "This study says a preference in taste for salt in a newborn is related
to higher blood pressure. The implication is it might be a way of screening people
who have salt sensitivity and could be prone to higher blood pressures or hypertension
later in life."
The study appears in today's issue of Hypertension: Journal of the American Heart
Association.
Zinner and his colleagues gave 283 healthy, 3-day-old babies a tiny taste of salt
on a nipple. The researchers then measured the babies' blood pressure and their
"sucking response" - how vigorously they sucked on the salt.
None of the babies actually liked the taste of salt. Some just minded it less than
others, Zinner says.
Babies with a relative salt preference had blood pressures that averaged 5 mmHg
(millimeters of mercury) higher than babies who had an "aversive" or "neutral" response.
The researchers measured the blood pressures again one month later. Babies with
a salt preference had a diastolic blood pressure that averaged 3.1 mmHg higher and
a systolic blood pressure that averaged 3.3 mmHg higher than babies who liked salt
the least. Systolic is the first, or top, number on a blood pressure reading; diastolic
is the second, or lower, number.
The relationship between salt preference and blood pressure was even stronger in
newborns who also had a grandparent being treated for high blood pressure. Babies
in this group had a diastolic blood pressure that was 5.0 mmHg higher and a systolic
pressure that was 6.7 mmHG higher than babies with an aversive response. A month
later, their pressures remained elevated.
None of the babies in the study had hypertension; some just had higher readings
than others.
The researchers also tested the babies' response to a sweet taste and found no correlation
between sucking response and blood pressure.
Dr. Theresa Roca, a staff pediatric cardiologist at the Ochsner Clinic in New Orleans,
says that the study is interesting, but that it's too early to use to help patients.
It remains to be seen if there is a link between a preference for salty foods in
adulthood and hypertension.
"It has never been shown that adults who are most salt-liking are more prone to
hypertension," Roca says. "You can't base any management of patients on this research."
She also cautions that taking blood pressure readings from infants is difficult,
mainly because they squirm.
It's estimated that about 26 percent of Americans with normal blood pressure and
about 58 percent of those with hypertension are salt sensitive, according to the
National Heart, Lung, and Blood Institute.
For adults who are salt sensitive, even a slight increase in salt in their diet
can cause an increase in blood pressure. African-Americans are particularly susceptible
to salt sensitivity, health experts say.
Previous research has shown that a low-salt diet can decrease blood pressure, both
diastolic and systolic, by as much as 10 mmHg. A normal blood pressure reading for
an adult is about 140 mmHg/90 mmHg, Roca says."