May 7/Minneapolis/KSTP -- Researchers at the University of Minnesota and St. Catherine University analyzed the menus of eight of the biggest fast food chains: McDonald's, Burger King, Wendy's, Taco Bell, KFC, Arby's, Jack in the Box, and Dairy Queen.
They tracked how the nutritional value of those menus has changed over more than a decade, and found most restaurants have made only modest gains.
Researchers scored those menus using the Healthy Eating Index. A perfectly nutritious meal is a 100. In 1997, those fast food restaurants registered a 45.
By 2010, that score had only climbed to a 48, well below what nutritionists consider a healthy diet. Experts stress that consumers can buy healthier options. But they want fast food chains to keep improving the health of their menus because they're such a big part of what Americans eat.
"Fast food restaurants are so ubiquitous in the American diet, and I think that it's important that they contribute to the wellness of our population," said Mary Hearst, director of the public health program at St. Catherine University, and lead researcher on the study.
Overall, researchers found that fast food has less saturated fat and calories than it used to. But there was no improvement in terms of fruits and vegetables.
The results also varied from restaurant to restaurant. KFC improved its nutrition the most, while Burger King and Wendy's were the only two to actually get less nutritious over time.