The power of water

09 November 2017
A drop of water

A new US study finds that encouraging children to drink water with their school lunches could prevent more than half a million youths from becoming overweight or obese.

The study, published in the journal Pediatric Obesity, suggests that this would also lead to reduced medical and societal costs in the region of $13 billion.

The findings are based on the nationwide programme introduced in 1,200 elementary and middle schools in New York City between 2009 and 2013.

All schools had water dispensers placed in cafeterias and this resulted in a trebling of students’ consumption of water at lunchtime.

It was also associated with small but significant declines in the students’ risk of being overweight one year later, the researchers found.

According to a cost-benefit analysis conducted by University of Illinois expanding the programme to all public and private schools nationwide would cost a total of about $18 for the entirety of each student’s 12 years at elementary and middle schools, but could yield an average net benefit to society of $174 across each person’s lifetime, or a total of $13 billion.

The New York City school students who drank more plain water consumed significantly less whole milk at lunchtime, but researcher Professor Ruopeng An says this is unlikely to pose any kind of nutritional hazards.

“The nutrition profile doesn’t change much when people increase their plain-water intake, but we do see a significant drop in their saturated fat and sugar intake,” he says.

“While there might potentially be some problems if children consume less whole milk, I would say those are probably minor in comparison with the costs associated with the skyrocketing rates of childhood overweight and obesity in the U.S.”

Professor An said the plain-water intervention’s projected long-term savings compared favourably with other population-level obesity-prevention policies, such as imposing excise taxes on sugar-sweetened beverages and enforcing nutrition standards for foods and drinks sold in schools outside of meals.

Prior researchers predicted that a sugar-sweetened beverage tax could prevent nearly 600,000 cases of child obesity, saving $14.2 billion across children’s lifetimes, while enforcing nutrition standards for non-meal food/beverages sold in schools would prevent 340,000 cases of child obesity, saving $800 million in lifetime costs. 

The economic impact of the water intervention was estimated to be greater among boys ($199) than girls ($149) because greater reductions were expected in the rates of overweight males than females (0.9 percent vs. 0.6 percent, respectively).

However, Professor An and his co-authors suggested that the probabilities of both sexes benefitting from the intervention were high.

The school-based water intervention also holds potential as a low- or moderate-cost population-level obesity-prevention intervention in developing countries, the researchers say.