Philadelphia's tax on all sweetened beverages — with or without sugar — reduced consumption among children and adults who were heavy consumers, while having no significant impact overall, a study published by the National Bureau of Economic Research has found.

The study by Mathematica Policy Research, the University of Iowa, and Cornell University collected data on price and availability of more than 1,200 sweetened and unsweetened beverages in more than 140 stores in Philadelphia and nearby counties. It measured buying habits before and after 2017, when the 1.5-cent-per-ounce tax went into effect.

While the tax didn't have a substantial impact on consumption by children overall, among children who drank the equivalent of 20 ounces or more per day, the tax did decrease consumption by about 22 percent. Among African American children, who have higher rates of sweetened beverage consumption nationally, the tax reduced consumption by about 8 grams, or 32 calories a day, the study found.

It found the cost of sugared drinks increased an average of 21 percent; that was passed on to consumers, with prices rising more in high-poverty neighborhoods. Stores decreased availability of both sugared and diet sodas, and increased stocks of untaxed beverages such as bottled water.