Babies who tolerate a salty flavor have higher blood pressure on average than their less tolerant counterparts do, a new study shows.
During the 30-month experiment, scientists measured blood pressures of 283 newborns at a Providence, R.I., hospital. The researchers also tested each baby’s taste preferences using a special nipple that delivers tiny drops of fluids and then records the intensity and frequency of a baby’s sucking. Each newborn received several rounds of drops of sweet liquids, salt-flavored ones, and plain water. Researchers conducted the taste tests 3 hours after a feeding.
All the babies showed energetic sucking responses to the sugar-flavored fluid and slightly less enthusiasm for plain water. In contrast, most showed an aversion to the taste of salt; they sucked less when given salt-flavored fluids rather than sweet liquids or plain water. Some of the babies, however, were less put off by the salt flavor than others were.
On average, babies who had the highest diastolic blood pressure–the bottom number on a blood pressure reading–tolerated salty flavor better than the babies with lower diastolic blood pressure did, the researchers report in the September Hypertension.
One month later, follow-up examinations of 234 of the babies revealed that those who had been more tolerant of salt flavor still averaged significantly higher blood pressure, compared to the other babies. This finding is reminiscent of research indicating that elevated blood pressure begins early and “remains on a track” throughout life, says study coauthor Stephen H. Zinner, an internist at Harvard Medical School in Boston and Mount Auburn Hospital in Cambridge, Mass.
“We know salt is related to blood pressure,” says endocrinologist Myron H. Weinberger of Indiana University Medical School in Indianapolis. “Developing tastes for salt may be something that occurs early in life and may then lead to high blood pressure later.” The new study, he says, “is a very important addition [to this field] because it suggests these differences in the aversion to the salt taste exist when the infants are born.”
Zinner suggests researchers could create risk profiles for children with elevated blood pressure and a salt taste preference so pediatricians could intervene “to keep them off salt.”
While the causes of high blood pressure are poorly understood, there’s evidence of a hereditary component. Indeed, in this study, babies with at least one grandparent who had high blood pressure had significantly higher average readings than did the other infants. In babies with a grandparent whose high blood pressure was serious enough to warrant medication, the link between salt taste tolerance and higher blood pressure was strongest, Zinner notes.