BOSTON — Finalization of the farm bill will affect how many children are eligible to participate in the U.S. Department of Agriculture’s Supplemental Nutrition Assistance Program, which includes the nation’s school nutrition programs. Beyond the debate taking place in Washington regarding eligibility, researchers continue to seek ways to improve the nutritional quality of school meals and instill eating behaviors that will remain ingrained well beyond childhood and into adulthood.

Researchers at Tufts University’s Friedman School of Nutrition Science and Policy, Boston, published a study in early July that looks at the potential benefits of limiting the availability of sugary beverages and expanding the availability of fruits and vegetables.

“Standards such as Smart Snacks in School have largely eliminated sugary drinks in U.S. public schools, but potential effects on obesity in children or long-term health are not known,” said Dariush Mozaffarian, M.D., dean of the Friedman School and senior author of the study. “Also, elementary schools in low-income neighborhoods often have free fresh fruits and vegetables programs, but these have not been expanded to other elementary, middle or high schools and potential long-term health effects have not been evaluated.”

The study, published in PLOS ONE, used a comparative risk assessment model to estimate the impact that implementing national food policies in U.S. elementary, middle and high schools may have on dietary intake and body mass index (B.M.I.) in children and what disease outcomes might be influenced in adulthood.

Girl with lunch in school cafeteria

“As children consume more than one-third of their daily meals and snacks in school, having policies focused on healthy food options in school is important,” said Katherine L. Rosettie, first and corresponding author of the study. Ms. Rosettie conducted the work when she was a research scholar at the Friedman School. She is now a researcher at the Institute for Health Metrics and Evaluation in Seattle. “What we need to know is how these policies are changing food choice, nutrition and health.”

The risk assessment model estimated the effects of a free fruits and vegetables provision and sugary drink limitations on diet and B.M.I. in children ages 5 to 18. Data from the National Health and Nutrition Examination Surveys for 2009-2010 and 2011-2012 on baseline B.M.I. and intakes of fruits, vegetables and sugar-sweetened beverages were used.

To estimate the effects of policies on long-term changes, the researchers used a meta-analysis of long-term within-person correlations of childhood and adult diets, meta-analyses of diet and cardiometabolic disease, and data on national cardiometabolic disease deaths from the National Center for Health Statistics for 2012.

A provision for free fruits and vegetables would lead to an increase in habitual consumption across school-age children over a period of 1 to 2 years, with a 17% increase for children in elementary school, 22% in middle school and 25% in high school, according to the study.

Child drinking sodaThe study showed a limitation on sugary drinks would decrease habitual consumption and have a modest effect on B.M.I. across school-age children, with a 27% decrease in consumption and 0.7% decrease in B.M.I. for children in elementary school, 19% and 0.5% for children in middle school, and 15% and 0.5% for students in high school.

The researchers then estimated that if such school food policies had been implemented when current adults were children, a provision for fruits and vegetables would increase fruit intake of the adults by 19% and vegetable intake by 2% and decrease consumption of sugary drinks by 24%.

If they had been implemented together, the researchers estimated the free fruits and vegetables provision and limitation on sugary drinks would prevent more than 22,000 adult deaths per year due to heart disease, diabetes or stroke, or 3% of total annual cardiometabolic deaths. Reduced consumption of sugary drinks was estimated to have the largest impact, averting more than 14,000 adult deaths per year.

“Identifying the benefits of school food policies helps to inform how to enhance these programs as well as the potential for harm if they were to be weakened or cut,” Dr. Mozaffarian said. “Our findings suggest that eliminating sugary drinks and providing free fruits and vegetables in schools has small effects on obesity in childhood but real potential for meaningful long-term health benefits into adulthood.”