Study authors note that in the spring of 2004, nearly 40% of elementary schools offered soft drinks, most of those coming from vending machines.
The majority of study participants were defined as non-Hispanic white children living in households above the poverty line.
Twenty percent of the respondents were considered overweight, which is in line with the national average of nearly 20% of all 6- to 11-year-olds deemed overweight.
The study was led by Meenakshi Fernandes, MPhil, doctoral fellow of the Pardee RAND Graduate School.
Researchers looked at the soda drinking patterns of thousands of fifth-graders from 2,303 schools in 40 states.
Soft Drinks in Elementary Schools
Here's what the researchers found:
26% of children who have access to soft drinks at school drink at least one soda a week while there.
Children from lower-income households and African-American children are more likely overall to drink sodas and to drink more sodas at school than other children.
In schools where sodas were limited, there was a 4% decrease in overall consumption.
Study authors admit the study has limitations because young children were asked to report how many sodas they drank a week.
Researchers add that older children may be more greatly affected by vending machines at school because they often have more pocket money and less teacher or adult supervision.
The study authors write that tougher measures may be needed, such as zoning regulations on "food outlet types" and promoting healthier food and beverage choices.
The authors note that in May 2006, the Alliance for a Healthier Generation and the American Beverage Association reached an agreement to restrict soda and snack foods (what they call "competitive foods") from being sold in schools.
There is no national law restricting vending machines in public schools. In 2003, California became the first state to outlaw the sale of soft drinks in public elementary schools.
Since then, other elementary schools across the country have followed suit. A law in Indiana requires that 50% of all food available for sale in public schools meet certain nutritional standards.
Money made from vending machines often goes to fund field trips, band, and other extracurricular activities.
Fewer schools in the western U.S. have soft drinks available on campus (16%) when compared to the national average of nearly 40%.
The research was funded by the Robert Wood Johnson Foundation's Healthy Eating Research program.