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Oh Baby, Is That Where Hypertension Starts?

Infants who prefer salty foods have higher blood pressure

FRIDAY, Aug. 9, 2002 (HealthDayNews) -- 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.

What To Do

The American Dietetic Association has tips for reducing salt in your diet. For more information on hypertension, visit the National Hypertension Association.

SOURCES: Stephen Zinner, M.D., chairman of medicine, Harvard Medical School, Boston; Theresa Roca, M.D., staff pediatric cardiologist, the Ochsner Clinic, New Orleans; Aug. 9, 2002, Hypertension: Journal of the American Heart Association
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