Children receive about 14 percent of their calories from fast-food restaurants, with burger joints leading the way, according to a recent study by the University of Washington School of Public Health.

Researchers from the School's Center for Public Health Nutrition set about to determine how different types of fast-food restaurants contributed to the diets of U.S. children. They analyzed data from more than 12,000 children ages 4 to 19 in the National Health and Nutrition Examination Survey for the years 2003 to 2010. Using a unique algorithm they created, the researchers estimated consumption of energy, sodium, added sugars and solid fats from each segment of the fast-food sector.

The study was published in PLOS One and co-authored by Colin Rehm and Adam Drewnowski. The authors found that more than a third of all children consumed fast-food items on any given day. Burger restaurants provided the most energy (6.2 percent) within the fast-food category, followed by pizza restaurants (3.3 percent). Sandwich, chicken and Mexican restaurants each provided less than 1.5 percent of total energy, while coffee/snack shops and Asian and fish fast-food restaurants each provided less than 0.5 percent of total energy.

"While the contribution of all fast food restaurants to children's diets in the US has been described previously, the real contribution of this study is providing, for the first time, estimates of the contribution for different types of fast-food restaurants to dietary intake," said Rehm, who earned his PhD in Epidemiology at the University of Washington earlier this year and is now a postdoctoral researcher at Tufts University. "Given justified concerns regarding the quality of diets consumed by American children, it is essential that dietary intakes be monitored and tracked with as fine a resolution as possible. This approach refines our view of children's diets and will prove valuable in monitoring trends looking forward."

Overall, foods and beverages from supermarkets and grocery stores accounted for the bulk of dietary energy (65 percent), sodium (62 percent), added sugars (69 percent) and solid fats (60 percent). Fast-food restaurants were the next most important source of these dietary factors, accounting for 14 percent of total energy, 16 percent of sodium, 10 percent of added sugars, and 18 percent of solid fats. Researchers said their new approach can also be adapted for other dietary outcomes, including fruit, vegetable and fiber consumption.