Mandatory nutrition policies could be a valuable tool in helping high school students to lower their sugar intake, a University of Waterloo study has found.

The study compared the consumption of sugar-sweetened drinks between 41,000 secondary school students in Ontario, where school nutrition policies are mandatory, and Alberta, where they are voluntary. The study took place during the 2013-14 school year.

It found that students in Alberta had a 16 per cent higher rate of sugar-sweetened beverage consumption compared to their counterparts in Ontario, where the sale of most sugar-sweetened drinks in secondary schools have been prohibited since 2011.

"These findings have implications on how we approach efforts to promote healthy dietary habits among adolescents," said Katelyn Godin, lead researcher and PhD candidate at Waterloo. "We need to devise strategies to improve the broader food environment so that healthier dietary choices are attractive and accessible, as well as improve students' food and nutrition-related attitudes, knowledge, values, and skills."

The study also found that students' meal and snack purchases outside of school and on weekends had a greater bearing on their beverage intake than their purchases in school food outlets. Godin believes this reflects how many teens spend their leisure time with friends, such as going out for food, to sporting and music events, or shopping -- all places where sugary drinks are readily available.

"Our findings suggest that while nutrition standards in schools could have an impact on sugar-sweetened beverage consumption, those standards alone won't be enough to dramatically curb adolescents' intake of these drinks," said Godin. "Given the important role of diet in chronic disease prevention, adolescents should be a priority group for intervention because poor dietary habits formed in childhood and adolescence often persist into adulthood."

According to previous studies, adolescents are the largest consumers of sugar-sweetened drinks in Canada, with many school age students consuming such beverages daily. Soft drinks and other sweetened beverages are linked to higher rates of obesity, cardiovascular disease, and a lower intake of vitamins and nutrients.

The research in the study was collected by the COMPASS research group at Waterloo, which aims to generate knowledge and evidence to advance youth health.

This study was done in collaboration with Scott Leatherdale, David Hammond, and Ashok Chaurasia, all professors at Waterloo's School of Public Health and Health Systems. It was published in the Journal of Nutrition Education and Behavior.