April 12 (UPI) -- Many of the meals consumed in the United States have poor nutritional quality, with the most nutritious eaten by children at school, a study published Monday by JAMA Network Open found.
About 65% of adult meals and 80% of children's meals from restaurants had low nutritional value In 2018, the most recent year for which information is available, researchers reported.
That same year, 44% of adult meals and 52% of children's meals purchased from entertainment venues and food trucks were unhealthy, the data showed.
At work, 51% of adult meals eaten were of poor dietary quality while, for children, 24% of meals consumed at school were unhealthy, the data showed.
In addition, one in three of adult meals and 45% of children's meals obtained from grocery stores, where about two-thirds of calories consumed in the United States are sourced, offered low levels of nutrition.
"Schools are now the single healthiest place Americans are eating. This finding is particularly timely given widespread school closures over the last year from COVID-19," study co-author Dariush Mozaffarian said in a press release.
"Our results suggest substantial nutritional harms for millions of kids who have not been consistently receiving meals at school and must rely on other sources," said Mozaffarian, dean of the Gerald J. and Dorothy R. Friedman School of Nutrition Science and Policy at Tufts University in Medford, Mass.
For this study, Mozaffarian and his colleagues analyzed the diets of about 40,000 adults and 21,000 children between 2003 and 2018.
The passage of the federal Healthy, Hunger-Free Kids Act in 2010 ushered in "significant improvements" in meal nutritional quality nationally, the researchers said.
From 2003 to 2018, the proportion of food with poor nutritional quality at schools was cut by more than half, to 24% from 57%, the data showed.
Over the same period, the proportion of unhealthy food consumed from grocery stores fell to 45% from 53%, while the proportion of food of poor nutritional quality consumed from restaurants declined to 80% from 85%.
Grocery stores accounted for 65% of calories consumed by children and 67% by adults, while restaurants made up 19% of calories for children and 22% of calories for adults, according to the researchers.
Food trucks, entertainment venues and schools each accounted for fewer than 10% of calories consumed for children and 9% for adults, they said.
"Our results underscore the fact that the nutritional quality of most meals, snacks and drinks consumed in the U.S. remains poor, and with important differences by where the food is obtained," Mozaffarian said.
"Improvement in schools was especially striking ... [and] clearly linked to the 2010 Healthy Hunger-Free Kids Act, a powerful lesson on how a single federal policy can improve both nutrition and equity for millions of Americans," he said.