BOSTON—Getting kids to eat their veggies can be a struggle, especially when it comes to broccoli, Brussels sprouts, and bitter greens. But simply adding a small sprinkle of sugar boosts their appeal to children—and increases how much they actually eat at school—according to preliminary findings presented here today at the annual meeting of the American Association for the Advancement of Science (which publishes ScienceNOW). "A major question is how to get people to eat more fruits and vegetables," comments Paul Breslin of Rutgers University in New Brunswick, New Jersey. "Any research efforts that accomplish that are to be praised."
There have been a lot of efforts to get kids to eat healthier lunches at school, but they haven't had a huge amount of success. The first meta-analysis, published last year, looked at 27 programs—such as teaching the importance of eating well—and found only minimal increases in consumption of vegetables. (Fruit fared better, as you might expect.) Better flavor is the missing ingredient, says Valerie Duffy, a dietician and researcher at the University of Connecticut, Storrs, because kids have more sensitive palates than adults do. "We need to pay more attention to taste and improving preferences for vegetables," so that kids will develop a long-term affinity for vegetables, she said during her presentation.
Bitterness can be minimized in several ways. Even a small amount of sugar spooned into a cup of coffee, for example, will send a strong signal to the brain. Salt blocks the sensation in the mouth, as does acidity. Fat coats the taste buds and prevents the offending molecules from reaching them; that's one reason salad dressings are popular around the world. Duffy and several colleagues conducted a laboratory study of some of these approaches in 37 adults. When the volunteers munched on asparagus, Brussels sprouts, and kale, sweetness was most effective at increasing the appeal of the vegetables. And only sugar was able to change the opinion of people who hadn't liked Brussels sprouts or kale, Duffy told the audience. The findings are described in detail in the December 2012 issue of Chemosensory Perception.
Duffy is also investigating the impact of adding sweeteners to broccoli, spinach, or collard greens served to preschoolers. In this study, funded by the American Diabetes Association, researchers offered kids two servings of the same vegetable. In a double-blinded experiment, they lightly misted one serving with plain water and the other with a dilute solution of aspartame. Two out of three kids preferred the vegetables that had been sweetened. When the team served some kids the lightly sweetened vegetables for a month, they ate slightly more vegetables. One reason that consumption might not have been higher, given the increased appeal, is the other food on the plates, Duffy said. It could be that the kids filled up on pizza or chicken nuggets before turning to the veggies.
The sweetener itself shouldn't be a concern to parents, Duffy said. All that's needed is a fraction of a teaspoon, just enough to balance the bitterness. In addition, after the kids have eaten the sweetened vegetables a few times, sugar can be eliminated and they will continue liking the vegetables, according to studies published by other researchers. Still, it may be a challenge to implement this approach, notes Adam Drewnowski of the University of Washington, Seattle. The findings "put sensory science in direct conflict with public health initiatives aimed at removing salt, sugar, and fat from school meals," he writes to ScienceNOW in an e-mail, "leaving the kids with nothing but the bitter taste of steamed cabbage."