"The foods that children are exposed to early on in life influence the pattern for their eating habits as adults," said Madhuri Kakarala, M.D., Ph.D., lead study author and clinical lecturer of internal medicine at the U.M. Medical School.
Earlier studies assessing the nutritional value of school lunches and the impact they have on children's overall health have found similar results, but this study is the first to also consider competitive foods and beverages – those sold at snack bars or vending machines – rather than through the U.S.D.A. lunch program.
Data from 2,309 children in grades 1 through 12 from schools throughout the country was analyzed. Interviewers administered questionnaires to obtain 24-hour food intake data on a given school day. Second-day food intake data was obtained from a group of students to account for day-to-day usual intakes.
Twenty-two percent of school children surveyed consumed competitive or vended food items in a school day. Usage was highest in high school, where 88% of schools had vending machines, compared to 52% of middle schools and 16% of elementary schools. Competitive food and beverage consumers had significantly higher sugar intakes and lower dietary fiber, vitamin B levels and iron intakes than non-consumers, researchers said.
Soft drinks accounted for more than two-thirds of beverages offered in school vending machines and stores. Desserts and fried snacks were the most commonly consumed vended items among elementary school children and beverages other than milk and fruit juice were the most commonly consumed items among middle and high school students. Other frequently consumed vended foods included candy, snack chips, crackers, cookies, cakes and ice cream.
Results did not show a significant difference in students' consumption of these items based on family income or race and ethnicity.
"Consumption of vended foods and beverages currently offered in U.S. schools is detrimental to children's diet quality," Ms. Kakarala said. "Childhood obesity, resulting from poor dietary choices, such as those found in this study, greatly increases the risk for many chronic diseases. A healthy school food environment can reduce these dietary risks."
The study authors recommend school administrators design guidelines restricting vended and competitive foods and beverages to those that are rich with nutrients and not energy-dense. School foodservice personnel can also prepare point-of-service materials and displays to promote more healthful foods such as fresh fruit, yogurt, low-fat milk, juice and sandwiches.