A simple solution: water jet machines placed in schools resulted in lower BMIs in students in New York.
It may sound simple, but, "sometimes, a very simple intervention can have a powerful effect," write researchers in a related editorial to the study, which is published in JAMA Pediatrics.
Lead study author Brian Elbel, PhD, of the New York University School of Medicine, and colleagues note that water is not only essential for human function, but also it prevents dehydration and is "critical to a nutritious diet."
Additionally, water provides a healthy alternative to sugar-sweetened beverages (SSBs), which have been linked to obesity in children.
The researchers explain that in 2009, New York City's Department of Health and Mental Hygiene and Department of Education introduced "water jets" into schools.
The so-called water jets are large, clear, electronically powered jugs with a lever for dispensing water.
Each of the water jets costs around $1,000, and about 40% of schools in the area received a water jet during the study's duration, which ran from 2008-2013.
Water jets linked with decreased BMIs in students
Elbel and his team wanted to assess the effect the water jets had on student body mass index (BMI), overweight and obesity. They also looked at milk purchases as a potential mechanism behind weight loss.
- Obese children and adolescents are more likely to be obese as adults
- Adolescents with obesity are more likely to have prediabetes
- Obese children have a greater risk for bone and joint problems, sleep apnea and social and psychological problems.
They note that although milk is promoted as a healthy beverage for children, it still contains calories - particularly chocolate milk, which contains added sugar. For example, one half-pint of fat-free chocolate milk has about 20 g of sugar, half of which is added sugar.
In total, the study included 1,227 public elementary and middle schools, with over 1 million students.
Of the schools, about 40% received a water jet and 60% did not.
Results showed that for boys, water jets were linked with a 0.025 decrease in standardized BMI, a 0.9% reduction in the likelihood of being overweight and 0.5% reduction in likelihood of obesity. For girls, there was a 0.022 reduction in BMI and 0.6% decrease in the likelihood of being overweight.
Additionally, the team found that water jets were linked with a decrease of half-pints of chocolate milk students purchased. In detail, there was a decrease of 12.3 half-pints per student per year.
The researchers say a possible explanation for their finding that chocolate milk purchases decreased is that "some children might not like white milk, and when given the option for chocolate choose that instead. When water is then introduced, they switch away from chocolate milk and toward water."
Study 'adds to evidence supporting water access in schools'
Although the study benefits from a large group of participants, the authors admit some limitations.
Firstly, they used administrative data on water jet delivery, rather than observing use in the cafeteria. Secondly, they also used administrative data on kitchen milk purchases and, therefore, lack data on milk consumption.
Still, Elbel is optimistic about their findings and says:
"This study demonstrates that doing something as simple as providing free and readily available water to students may have positive impacts on their overall health, particularly weight management.
Our findings suggest that this relatively low-cost intervention is, in fact, working."
In a linked editorial, Lindsey Turner, PhD, of Boise State University in Idaho, and Erin Hager, PhD, of the University of Maryland School of Medicine in Baltimore, write about the significance of the findings.
They say the study "adds to a growing body of evidence supporting the importance of providing drinking water access in schools." Turner and Hager add that the findings demonstrate "that water access in schools can promote healthy weight outcomes among students."
Medical News Today recently reported on a study that suggested health warning labels could stop parents from buying sugary drinks for kids.