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Q+A: The Public Health Effects of a Philly Soda Tax

March 1, 2016

To date, only one city in the United States has passed a soda tax: Berkeley California. But Mayor Jim Kenney reportedly hopes to have Philadelphia soon join the west coast city in taxing sugary beverages.

Several articles from around the city indicate that Kenney hopes to make a soda tax part of his inaugural budget. This effort follows attempts by the previous, Michael Nutter administration to pass such a tax.

But what can happen if such a tax is passed? Could it really make people healthier?

Dave Kern, an epidemiology PhD candidate in Drexel’s Dornsife School of Public Health, is in the midst of studying the price impact of food and beverage products and their correlation with health. 

He recently shared his thoughts on what the public health impact might be of a soda tax and what Kenney might have to fight against to enact it.

Is soda really that bad for you?

There are well-known links between consumption of added sugars and dietary quality, in general. That includes risks for obesity, diabetes and cardiovascular disease, in particular. Recent United States dietary guidelines highlight those relationships and motivated recommendations to limit sugar intake.

On average, close to 20 percent of U.S. adults and nearly 50 percent of children are consuming at least one soda per day (or six per week) and prevalence of soft drink consumption is even higher among Latinos and blacks — demographic groups with higher risk for obesity and diabetes.

What kinds of obstacles could such a tax face?

The soft drink industry is spending over $3 billion a year marketing carbonated beverages and has lobbied very hard to successfully block municipal soda taxes (with the exception of Berkeley California).

To date, only very small “junk food”/soda taxes have been implemented or proposed. Obviously, the higher the tax, the more that consumers will shift their behavior.

However, even under modest tax scenarios, some simulation studies conclude that — while taxes may have only modest effects on body mass index (BMI) — small changes in BMI could have favorable primary or tertiary impacts on diabetes and cardiovascular disease.

So would a tax dissuade people from buying unhealthy items?

Public health experts generally agree with economists that prices clearly have the potential to affect food/beverage purchasing patterns — particularly in combination with marketing and availability.

I’m working on specifically trying to quantify price differentials between healthier and unhealthy products. My new work is finding that, on average, the price of soda is 60 percent lower than the price of milk — which illustrates potential “incentives” that soda prices may exert on consumer decision-making. My research is finding that soda is cheapest in areas with higher concentrations of black and Hispanic individuals and in areas of lower socio-economic status — thus potentially adding additional incentives to purchase soda in high-risk communities.

In follow-up work, I expect to see price impacts on diet quality and risk for diabetes. I’m using prices from a national sample of 1,700 supermarkets and will be linking these data to a cohort study that has detailed dietary and health outcome data.

Any media interested in speaking to Kern can contact Frank Otto at 215.571.4244 or at