Junk Food Tax Could Improve Health

March 10, 2010— -- Taxing junk food may help reduce obesity and improve health, researchers have found.

Patients got significantly less of their calories from soda or pizza when there was a 10 percent increase in the price of either, Penny Gordon-Larsen of the University of North Carolina at Chapel Hill and colleagues reported in the March 8 issue of Archives of Internal Medicine.

"Policies aimed at altering the price of soda or ... pizza may be effective mechanisms to steer U.S. adults toward a more healthful diet and help reduce long-term weight gain or insulin levels over time," the researchers wrote.

Talk of a soda tax has sparked debate across the country, particularly in New York and Philadelphia, where such legislation is currently under consideration. However, not much research has been done to study how price changes would affect health outcomes.

So the researchers looked at data from 5,115 patients enrolled in the longitudinal Coronary Artery Risk Development in Young Adults (CARDIA) Study from 1985 to 2006.

During that time, the inflation-adjusted price of soda and pizza actually decreased, with the largest drop observed for soda, falling from $2.71 to $1.42 for a 2-liter bottle -- a 48 percent decline.

In their analyses, the researchers found that changes in the price of soda and pizza were associated with changes in the probability of consuming those foods, as well as in the amounts consumed.

A 10 percent increase in the price of soda was associated with a 7.12 percent decrease in calories consumed from it, while the same increase in the price of pizza led to an 11.5 percent drop.

Price was also significantly associated with total caloric intake and body weight. A $1.00 increase in soda prices, for example, was tied to a mean of 124 fewer total daily calories, which amounted to an average weight loss of 2.34 pounds.

The researchers noted that similar trends were seen for pizza, adding that a $1.00 increase in the price of both soda and pizza together was associated with even greater changes in total energy intake, body weight, and insulin resistance.