WASHINGTON -- The kids keep pushing away the spinach and broccoli? Wait a few years.
Researchers say sensitivity to bitterness in food appears to decline with age, making vegetables more palatable as people grow older.
A study to be published in Health Psychology found that women were less sensitive to bitter-tasting food as they got older and showed an increasing preference for vegetables, whole-grain foods and beverages such as coffee and tea. Their like for fruits, meat and dairy products did not change with age.
"Taste is the driving factor" in what people decide to eat, said study author Adam Drewnowski, director of the nutritional sciences program at the University of Washington. "Your preferences will change with age."
He presented his research Wednesday at an Agriculture Department conference on dietary behavior. Scientists hope that by better understanding why people choose certain foods, they can improve nutrition and stop the nationwide increase in obesity.
"The fact is that unhealthful living and obesity shortens lives and has the opportunity to make you sick for a longer period of time," Agriculture Secretary Dan Glickman said.
Studies have found a number of factors influence what children and adults eat, including their previous experience with different foods, their culture and family environment and their activity level. For example, people who exercise a lot tend to consume more fat and sugar.
But researchers also have been finding a strong inherited tendency to like or reject different types of food. Healthly foods like broccoli, brussels sprouts and mustard greens, which are naturally bitter anyway, can seem especially so to people who are particularly sensitive to bitterness.
Drewnowski's study, conducted at the University of Michigan, tested the taste sensitivity of 329 women, ages 21 through 84, who went to a breast-care clinic for examination, diagnosis or treatment. Such sensitivity is measured by response to a a thyroid medicine called 6-n-propylthiouracil, or PROP. The women, none of whom had surgery or chemotherapy yet, also were asked what food they liked and what they actually ate.
There was a close correlation between the decline in sensitivity to bitterness and what foods the women liked and ate. "Age was the best predictor of healthy diets," the study concluded.
Additional research must be done to determine whether food preferences and taste sensitivities in males change to the same extent, Drewnowki said.
He believes oils and sugars should be used more often in cooking vegetables to make them more attractive to people, especially children, with sensitive palates.
"We're surprised that people don't eat bad tasting foods. We shouldn't be surprised," he said. "Any kind of public policy program based on changing dietary behavior must take taste into account. If you forget that it won't happen."
Health professionals, however, worry that his advice could increase intake of fat and unnecessary calories, exacerbating the very obesity problem that nutritionists are trying to address.
"Part of the reason you want to get children to eat fruits and vegetables is to limit fat consumption," said Tom Baranowski of the Baylor College of Medicine in Houston. The trick is to avoid adding excessive fat, he said.