Photo of soda/sugary drink being poured in glassHarvard researchers found that Boston Public School’s sugary drink policy helped 90 percent of the 115 schools meet the state’s nutrition standards for competitive beverages.

Competitive beverages are drinks sold outside of the federally reimbursable school meal program, including soft drinks, fruit drinks, sweetened teas and sports drinks. The drinks are found in some schools in such places as vending machines, school stores and snack bars.

The Harvard study found that more than 88 percent of Boston’s elementary schools and 61 percent of its middle schools didn’t sell competitive beverages. Only 4 percent of all students in Boston public schools had access to sugar-sweetened beverages.

Nationally, the numbers are significantly lower, and about 40 percent of district wellness policies ban soda in schools.

“Our study demonstrates that a comprehensive district-wide policy, in coordination with ongoing professional education, community-identified tools, and technical assistance training, can translate into a sustained healthier environment in public schools,” researchers wrote.