New York's Soda Prohibition Won't Work

New York City's plan to prohibit the sale of large, sugary soft drinks is a brave and provocative policy, one that promotes public health at minimal cost to New York City residents.

Mayor Michael Bloomberg’s announcement last week highlights the kind of tough regulatory action we, as a society, need to make to combat an obesity epidemic that experts say will cause this generation of elementary school children to be the first in centuries to experience a shorter life span than their parents.

As a physician who has written extensively about the unconscious forces that cause people to overeat, I believe that local and federal governments need to enact bold initiatives to combat our nation's obesity epidemic.

Unfortunately, the Big Gulp ban is a bad idea.

To understand why, compare the proposed ban on large sodas with the trans-fat ban that the city instituted several years ago. Both bans share many important features. In both cases, the product in question is undeniably unhealthy. Trans fats are known to be more likely to cause cardiac disease than any other commonly used cooking oil.

And in both cases, restaurants can turn to possible alternatives to substitute for the banned good. After the trans-fat ban, restaurants were able to switch to other cooking oils with no discernible deterioration in the flavor of their offerings. Should the large soda ban go into effect, restaurants will easily be able to offer smaller beverages to their customers without anyone suffering significant harm.

Where the trans-fat and soda bans differ, however, is in the coherence with which New York City officials can explain how they draw the line between banned and unbanned goods. Trans fats are a particularly odious class of substances, 80 percent of which are artificially manufactured and added to processed foods. By one estimate, a 2 percent increase in energy intake from trans fats was shown to increase the risk for heart problems by up to 23 percent. This risk of cardiac consequences dwarfs that of alternative fats.

Prior to the trans-fat ban, the city’s health department made earnest efforts to educate restaurants about the problems with trans fats. But these efforts were completely ineffective, as restauranteurs realized that the cost of transitioning to alternative cooking oils would leave them at a competitive disadvantage.

By banning trans fats in all restaurants, New York City leveled the playing field, with the cost of transitioning to alternatives now borne by all restaurants. These costs were a small price to pay for the public health benefits of the prohibition.

Coke and Pepsi are artificially manufactured processed foods, too. And they contain an undeniably harmful substance. But herein lies the problem. The harmful substance (now that Coca-Cola no longer contains cocaine) is sugar, and the sugar in Coca-Cola is no more harmful than the sugar in apple juice or a milkshake. This is understandably confusing to the public, who can't understand why New York City is planning to ban large sodas but not triple-decker chocolate cakes, or why the 280 calories in a 24-ounce Coke is somehow worse for them than the 330 calories in a Starbucks peppermint mocha.

The success of most policies depends upon public support. But incoherent policies are difficult to embrace.

If Mayor Bloomberg were defending his policy in front of the Supreme Court, the justices would be asking him for a limiting principle -- a rationale that would help us know where this policy begins and ends. The ban on large sodas doesn't pass this test.

If sugar is the culprit, the city's policies should go after that culprit wherever it lies. That would require a sweeping policy, such as a tax on all sugar products, not just Big Gulps. But that may be a policy many people will find hard to swallow.

Peter Ubel, a physician and behavioral scientist, is the John O. Blackburn Professor of Marketing at Duke University’s Fuqua School of Business and a professor at Duke’s Sanford School of Public Policy. He is author of the upcoming book “Critical Decisions:  How You and Your Doctor Can Make the Right Medical Choices Together” (HarperOne, September 2012.) This commentary was originally published in The Philadelphia Inquirer and The News & Observer on June 6, 2012.