Sodium content needs to be on the menu at Philly restaurants. Here's why

New legislation proposed Jan. 25 by Councilwoman Blondell Reynolds Brown will help Philadelphia restaurant-goers reduce their risk of stroke and heart disease.

The bill would require chain restaurants to put warning labels alongside menu items or meals containing at least an entire day's worth (2,300 mg) of sodium. Its aim is to let consumers make informed choices when dining out. If the legislation passes, Philadelphia will become the second city in the country, after New York, to implement such labels.

There is no time to waste. Of the 11 largest counties in the United States, Philadelphia has the highest obesity prevalence and the highest rate of premature death.

Nearly 50 percent of American adults have high blood pressure, putting them at great risk of suffering a stroke or developing heart disease, two of the leading killers of Americans. Because excessive sodium contributes to high blood pressure, reducing our sodium intake is important for our health. The Dietary Guidelines for Americans recommend that we eat no more than 2,300 mg of sodium a day. But nearly all of us are overshooting that goal, with 89 percent of Americans consuming more than that on a daily basis.

When we look at where we are getting all this sodium, we find that it doesn't come from using a salt shaker when cooking at home. Instead, it largely comes from packaged and restaurant foods. In fact, 25 percent of the sodium that Americans consume is from restaurant food, much of which contains jaw-dropping amounts. For example, TGIFriday's Southern Fried Buffalo Chicken Sandwich has 4,010 mg of sodium, while Chili's full rack of Texas Dry Rub Ribs has a whopping 5,000 mg of sodium — more than two day's worth.

I am a scientist at the Perelman School of Medicine at the University of Pennsylvania, where I direct the Psychology of Eating and Consumer Health (PEACH) lab. In our lab, we've studied how food labeling influences people. Perhaps it's not surprising that food labeling can encourage people to make healthier choices.

But food labeling can also influence packaged food companies and restaurants to offer healthier items. This happened when the Food and Drug Administration required trans fats—a harmful type of fat in foods—to be included on the nutrition facts label. Over time, food companies removed trans fats from their products so that they could proudly display "0 trans fat" on their labels. The mass removal of trans fats from the food supply following policies like food labeling requirements and banning trans fats in restaurants is already saving lives.

In my lab, we have conducted online experiments to study the potential effects of Philadelphia's proposed sodium warning labels. In these studies, we randomly assigned people to see different types of sodium warning labels prior to making judgments about restaurant foods. We found that exposing people to sodium warning labels improved their understanding of the sodium content in restaurant meals. We also found that the design of the label matters. Including the words "sodium warning" alongside a warning symbol like a stop sign was more helpful to consumers than showing a warning symbol without these words, like the current New York City label.

There are many reasons why Americans over-consume sodium, but one of the most important reasons is this: We have no idea how much sodium we are consuming when we eat at restaurants. Indeed, studies show that, on average, consumers underestimate the sodium in restaurant foods by 1,000 mg a meal. Consumers can't make healthy choices unless they understand which foods are healthy.

Placing sodium-warning labels on restaurant menus is a public health no-brainer. It's really hard for restaurant-goers to control their sodium intake if they don't know which foods are high in sodium. This legislation is an important next step in improving the health of Philadelphians. 

Christina A. Roberto, Ph.D., is assistant professor of medical ethics and health policy at the Perelman School of Medicine of the  University of Pennsylvania.