Harvard University researchers are projecting major health benefits if Mayor Kenney's proposed tax on sugar-sweetened beverages is enacted.
Within a few years of the three-cents-an-ounce tax's beginning, they forecast, nearly 2,300 diabetes diagnoses would be prevented annually, and eventually, 36,000 people a year would avoid obesity. Over a decade, about 730 deaths would be averted, and close to $200 million saved in health spending.
"It is just a total winner of a policy from a public health perspective," said Steven Gortmaker, who led the analysis, being released Thursday.
The mayor's argument for an excise tax that would add 36 cents to the cost of a can of soda has focused largely on the revenue it could provide for universal prekindergarten and other programs. Health benefits have taken a backseat in his campaign.
Multiple sugary-drink tax proposals around the country, including two by former Mayor Michael Nutter, have been defeated after intense lobbying by the beverage industry. It again is fighting hard to stop what would be a precedent-setting levy.
Most tax proposals around the country have emphasized projected health benefits. A change in strategy may be "a smart move," said Gortmaker, a health-sociology professor at Harvard's T.H. Chan School of Public Health. Gortmaker also directs the school's Prevention Research Center and has coauthored more than 60 papers on obesity.
The new analysis relies on previously published findings on the national impact of a one-cent tax. It then uses census and other data to simulate the combined experience of more than one million Philadelphians - a population that is poorer, and less healthy, than the national average.
Campaigning in Pennsylvania for the Democratic presidential nomination last week, Sen. Bernie Sanders came out against the tax as "regressive," an argument that the beverage industry has made. Rival Hillary Clinton said she supported the tax.
No one disagrees that lower-income people, who tend to drink more soda than the affluent, would be most affected financially. But the fact that they might also benefit most from cutting back on soda, Gortmaker said, makes the tax "progressive" for their health.
"Right now, they are spending a lot of their money on sugar-sweetened beverages that are, frankly, killing them," said Gortmaker, whose analysis was funded by the nonprofits Healthy Food America and JPB Foundation.
The analysis has not been peer-reviewed, meaning it has not been scrutinized by other scientists. Evidence that the liquid calories in sugary beverages are more harmful than solid calories has accumulated only in the last few years. The ultimate health impacts of that link have not been proved.
But in Philadelphia, the larger controversy may center on how consumers would respond to the tax.
Would they simply switch to bottled water and diet sodas, as proponents hope? Would they drive over the city line to buy sugary drinks, depriving the city of its new revenue source?
Kevin Dietly, an economics consultant who prepared estimates for the American Beverage Association, said the tax's impact on consumption and buying patterns is unknowable. Any health impacts are similarly unclear, he said, pointing to conflicting research on the topic.
The Philadelphia proposal is triple the size of the only sugary-drinks tax approved in the United States, a penny-per-ounce levy that Berkeley, Calif., began phasing in a year ago. It is so big, Dietly said, that standard economic theory "goes out the window." Not just consumers but even small businesses might smuggle in soda from a suburban discount retailer, he said.
Larry Ceisler, a spokesman for the beverage industry, said in an email that the industry had not focused on claims of health benefits, since Kenney had presented the tax as a revenue issue.
"The mayor has stated this is not about health. . . . So there would be no reason to address it, and I do not anticipate we would."
Eric M. Eisenstein, who teaches marketing and supply chain management at Temple University's Fox School of Business, thought soda-smuggling was unlikely in any significant volume, since most sales are through national retailers. But that doesn't necessarily mean the tax would improve health, Eisenstein said.
"The economists of the world think these things will have effectively zero impact on obesity," he said, because a lengthy chain of events would be required between imposing a tax and controlling weight. "The public health people think it matters a lot."
One of them is Thomas Farley, the city health commissioner. Farley held the same title in New York City, where he was former Mayor Michael Bloomberg's vocal partner in an ill-fated attempt to ban jumbo sodas. He has been less visible here - City Council has not asked for his testimony on health benefits, he said - but believes a tax will work.
"We have these twin epidemics of obesity and diabetes. We know that, if the price increases, people will switch to water or other beverages that don't have this high sugar content," Farley said. The new study, he said, confirmed for him that the tax is appropriate.
"There's no other single policy we could implement that would have this widespread, generational impact," he wrote Wednesday after seeing the study.
Preliminary Berkeley data presented at a conference a month ago appeared to support the Harvard model, at least for reduced consumption.
So do findings from Mexico's two-year-old tax on sugar-sweetened beverages, which has had the biggest effect on the lowest-income residents, said researcher Barry M. Popkin, who coauthored the Mexican study, published in the open-access journal BMJ.
Popkin, a nutritionist and economist at the University of North Carolina, has researched the pricing of sugar-sweetened beverages around the world. He predicted that Kenney's proposed tax, if approved by Council, would speed up the already significant decline in soda consumption and lead to a gradual improvement in health.
"The most important thing for Philadelphia is going to be the long-term effect on child obesity. It plays out their whole life. It continues as adults. Obesity doesn't kill you as much as it debilitates you. It puts you in retirement homes and takes you out of work," Popkin said.
"While the mayor is doing it for revenue reasons, it could have a very big impact on Philly."
By the numbers
36,000 obesity cases a year eventually prevented
2,280 cases of diabetes avoided each year
730 deaths averted over a decade
$197M in health-care costs saved
SOURCE: Harvard CHOICES project. Numbers in 10-year analysis are the most likely in a range.