• Health
  • Public Health

Soda Taxes Are a ‘No-Brainer’ for Public Health, Says the Author of a New Study on Them

4 minute read

A new JAMA study suggests taxing sugary drinks really can make people buy fewer of them, potentially translating to better public health.

Taxes on soda and other junk foods are frequently proposed as a way to coax Americans into eating more healthfully, and in turn cut rates of diet-related chronic diseases such as obesity, type 2 diabetes, cancer and heart disease. While Americans are drinking less soda than they used to, it’s still a major source of sweeteners and empty calories for many people, contributing to an estimated 25,000 premature deaths a year.

But lawmakers and health experts have debated whether taxes on sodas and other sugary beverages, such as fruit juices and energy drinks, are actually good policy. Studies conducted in places that have enacted soda taxes, such as Berkeley, Calif. and Mexico, suggest they can drive down sales, but opponents argue that the policies can’t replace public health education and unfairly target low-income people who can’t afford higher price tags. The soda industry is, unsurprisingly, also a vocal opponent—so much so that its influence helped sway lawmakers in California, home of the U.S.’ first soda tax, to ban future ones.

The new JAMA study examined the effects of Philadelphia’s decision to place an excise tax of 1.5¢ per oz. on sugar- and artificially sweetened drinks, starting January 2017. In the year after the policy went into effect, researchers found that sweetened beverage purchases dropped by 38% compared to the year before, translating to almost a billion fewer ounces of these beverages sold.

Study co-author Christina Roberto, an assistant professor of medical ethics and health policy at the University of Pennsylvania’s Perelman School of Medicine, says that could be especially meaningful in Philadelphia, the poorest of America’s 10 largest cities, and one plagued by widespread health problems.

“For decades, we’ve been losing this war on chronic diseases like type 2 diabetes. The reality is, over-consumption of these drinks is widespread and they’re making us sick,” Roberto says. “The sugar-sweetened beverage taxes, to me, offer some hope.”

For the new study, Roberto and her colleagues examined 291 chain stores’ beverage prices and sales in the year before and after the tax was implemented. They used nearby Baltimore, which is similar in demographics but does not have a soda tax, as a control city, and also looked at sales data in zip codes bordering Philadelphia that did not have soda taxes.

In the year following the tax’s roll out, sugary drink sales dropped in Philadelphia by just over 50%. But sales increased in bordering zip codes, suggesting that some Philadelphia shoppers were leaving city limits to purchase sodas, Roberto says. Given that assumption, researchers estimated the total decrease in sales at about 38%, according to the paper. Sales fell in Baltimore, in keeping with overall reductions in U.S. soda drinking, but far less dramatically: They dropped by about 13.3 million ounces, compared to about a billion ounces in Philadelphia, the researchers found.

The data were strong enough that Roberto calls soda taxes “a no-brainer”—not only because they likely prompt people to drink fewer sweetened beverages, but also because they drive revenue for city projects (in Philadelphia’s case, education and infrastructure) and help people save money.

“In our data, we actually don’t see people switching and buying other kinds of non-taxed drinks,” Roberto explains. “What that means is that money goes into their pockets or they’re able to spend it on other things.”

That finding is, in part, why Roberto says she doesn’t see an ethical problem with taxing soda and other junk foods. And while soda taxes may have an outsized impact on lower-income people, Roberto says they also stand to gain the most from them.

“The flip side of the ethical concern is that we have a system right now where diseases like type 2 diabetes and chronic diseases are disproportionately impacting those with the lowest resources and the greatest need,” she says. “Part of what this is trying to do is to help people make healthy choices that are going to help them lead a long life.”

In pursuit of that goal, Roberto says she’d support taxes on other junk foods. “If you expand it to other kinds of foods that we know to be really unhealthy,” Roberto says, “that would also do more to help public health.”

More Must-Reads from TIME

Write to Jamie Ducharme at jamie.ducharme@time.com