There's no question that the average American has a sweet—and a salty—tooth. The American Heart Association says we consume about 355 calories per day of sugar, more than three times its new recommended daily limit of 100 calories for women and twice the 150-calorie cap for men. And the Centers for Disease Control and Prevention said in March that the average American age 2 or over consumes 3,436 milligrams of sodium per day; nearly 70 percent of adults fall into higher-risk groups that should take in only 1,500 mg per day, and the rest of us are advised to top out at 2,300 mg.
Not surprisingly, there's been a chorus of voices saying we need to make changes to what and how we eat. In April, two nutrition experts at the Harvard School of Public Health called for a switch to less sugary drinks: things like water, tea, seltzer with a splash of juice, and coffee with one lump of sugar. And they called on beverage makers to create reduced-calorie drinks with no more than a gram of sugar per ounce. The goal is not to compensate with noncaloric sweeteners like asparatame or stevia. Though there's not definitive research to prove it, constantly drinking sweet beverages, even if noncaloric, may set us up to look for other similarly sweet foods and drinks during the day, says Lilian Cheung, a lecturer at Harvard and one of the proposal's authors.
There have also been numerous requests by the American Medical Association and other medical groups for manufacturers to cut the amount of sodium in processed foods by as much as half, with the aim of reducing rates of high blood pressure, heart problems, and stroke. A recent report by the Institute of Medicine called on the government to cut the sodium in school meals; an average high school lunch now has about 1,600 mg of sodium, and the report says that should drop to no more than 740 mg.
[Check out: 10 Salt Shockers That Could Make Hypertension Worse.]
But as anyone who has struggled with a yogurt-covered pretzel habit can confirm, sweet and salt can be quite the siren song. (Former FDA Commissioner David Kessler explains how the food industry takes advantage of those preferences, as well as our enjoyment of fat, in his recent book, The End of Overeating.) Even newborns have a strong positive response to sweet, says Gary Beauchamp, director of the Monell Chemical Senses Center in Philadelphia. That preference declines a bit during adolescence, for unknown reasons. And he says that though there's certainly variation in how much we like sweet, at least among older kids, we don't know what causes that; there's some evidence that there are genetic differences in sweet receptors, but it's also possible that what kids eat when they're very young can influence their sweet preferences in childhood and adulthood. Less clear is how the preference for salt develops, says Beauchamp. Not all infants like the taste, but "by the time they're 2 or 3, they show a high preference for salty foods, just like adults," he says. In fact, kids like things even saltier than adults.
However, even if a preference is innate, that doesn't mean it can't be changed through experience, says Beauchamp. Debra Zellner, a psychologist at Montclair State University who studies food cravings and taste, has done research that shows your sweet preference can indeed be jacked up by repeated exposure to sugary foods and drinks. "Your ideal point on sweetness will increase. So what originally might have tasted good to you—a very low sweetness level—after ingesting a lot of beverages that are very, very sweet won't taste good anymore," she says. In theory, the mechanism should work the other way, too, she says—though the research to prove it hasn't been done. Evidence on switching to a low-sodium diet, at least in adults, shows that it's hard to make an abrupt change, says Helen Jensen, an economics professor at Iowa State University who was on the IOM's school meals panel. That's one of the reasons the panel recommended sodium be reduced over 10 years; there's not much research on how changes in saltiness will affect palatability in kids, and "the last thing we want to do is make a change that [takes] kids out of the program, so they're not consuming school lunches at all," she says.