Taste for Salt May Be Shaped During Infancy
By Amanda Gardner
WEDNESDAY, December 21, 2011 (Health.com) — People who sprinkle salt on everything and gravitate toward unhealthy high-sodium foods may be expressing a taste preference formed during early infancy, a small new study suggests.
Researchers found that six-month-old babies are more likely to enjoy the taste of salt if they have already been given starchy table foods such as cereal and crackers, the most common source of sodium for babies.
And this affinity for salt appears to be lasting. Once they'd reached preschool age, the kids in the study who were exposed to sodium as infants were apt to prefer salty foods such as potato chips, hot dogs, and french fries—and some showed signs of being salt fanatics, going so far as to lick salt crystals off pretzels or eat salt plain.
By contrast, infants who stayed on baby food in their first six months, or who were given only fruit in addition to baby food, were more likely to be indifferent to salt as they matured.
"The implication is that this very early dietary experience may have a prolonged effect on how much individuals like the taste of salt," says Leslie J. Stein, Ph.D., the lead author of the study and a senior research associate at Monell Chemical Senses Center, in Philadelphia.
The findings, published this week in the American Journal of Clinical Nutrition, raise the possibility that delaying early exposure to sodium could help create a nation of adults who are less fond of salt and high-sodium foods, both of which can raise blood pressure and increase the risk of heart disease and stroke when consumed to excess.
"In Paleolithic times infants had breast milk for two to three years, but in modern culture, many kids go to processed foods, where the factory decides how much salt to put in," says Philip J. Klemmer, MD, a professor of medicine at the University of North Carolina School of Medicine, in Chapel Hill, who was not involved in the new research.
The way the babies in the study seem to have developed a taste for salt is "almost like imprinting," Klemmer says, referring to the process by which infants bond with their parents and learn other social behaviors.
Next page: When does salt taste begin?
When babies are born, they don't react to the taste of salt like they do to other tastes, such as sweet or bitter. "Either the baby can't detect salt or the baby just doesn't care about salt," Stein says. But babies begin to register salt taste sometime between the ages of two months and six months.
To explore what's behind that shift, Stein and her colleagues gave bottles filled with plain water and two saltwater solutions—one salty (2% sodium) and one not so salty (1%)—to 61 two-month-old infants, and gauged their preference by measuring how much of each they drank.
Then, when the babies were six months old, the researchers repeated the test and also surveyed the mothers about the foods they'd introduced. The questionnaire covered baby foods (which are almost always sodium-free), low-sodium table foods such as fruits and vegetables, and higher-sodium foods such as crackers and cereal. (Cheerios, which often are recommended for infants, contain 120 milligrams of sodium per child-size serving, for instance.)
At two months, the babies showed no discernible preference for the salt solutions. At six months, however, babies who had already been introduced to starchy table foods preferred the taste of salt to plain water. The babies who hadn't yet tried table foods were either indifferent to the higher-salt solution or actually rejected it.
Twenty-six of the children were tested again when they were between the ages of 3 and 4, and those who'd displayed a preference for salt at six months continued, as a group, to prefer the salt solutions. According to their mothers, these kids also were more likely than the others in the study to like salty foods.
The study did have some shortcomings. For instance, the actual salt content of food consumed by the children wasn't measured (although starchy table foods are known to contain more sodium than baby foods or fruit). Nor do the findings prove a cause-and-effect relationship, the authors say.
John E. Hayes, Ph.D., an assistant professor of food science at the Pennsylvania State College of Agricultural Sciences, in College Park, says the researchers also may have underestimated the innate preference some infants have for salt. Some studies have shown that newborns as young as two days to four days old may have a preference for salt, sucking harder at bottles that contain salt solution, Hayes says.
Untangling how salt preferences form has important implications for public health, because people's attachment to salty taste is among the biggest obstacles in bringing sodium intake down to healthy levels. Nearly 90% of Americans consume more sodium per day than is recommended, according to an October report from the Centers for Disease Control and Prevention.
In recent years, public-health officials have increasingly urged Americans to reduce their sodium consumption and have encouraged food companies to scale back the sodium they use, but these messages have gone largely unheeded. Some food manufacturers have been reluctant to use less sodium for fear of losing customers to saltier competitors.