ANN ARBOR—Restaurants are reducing sodium in some newer items on their menus, but when it comes to existing fare and use of sodium overall there has been little change, according to research led by the University of Michigan.

Julia Wolfson, assistant professor of health management and policy and of nutritional sciences at the U-M School of Public Health, and colleagues examined menu items from 66 of the top 100 chain restaurants and found that while some attention has been given to offering lower-sodium options, restaurant food is still high in sodium, particularly in main-course items. High-sodium diets have serious adverse health effects.

“Overall, sodium content of newly introduced menu items declined by about 104 milligrams. However, among existing and new main-course items, the average sodium content of a single menu item is still more than half of the daily sodium recommended limit of 2,300 mg,” Wolfson said.

“The fact that new, lower-sodium menu items are being introduced indicates that it is possible for restaurants to reduce the sodium content of their food, but that, thus far, their efforts have been insufficient. Restaurants may be reluctant to reformulate existing menu items that are popular with customers and that define their brand.”

Using data from the MenuStat project, Wolfson and colleagues at the Harvard T.H. Chan School of Public Health and the University of Pittsburgh looked at nearly 22,000 menu items in fast-food, fast-casual (think Jimmy Johns and Panera) and full-service chain restaurants over the period 2012 to 2016. The database contains calorie and nutrition data gathered from websites of the 200 largest restaurants in the United States, as defined by sales volume.

The researchers compared sodium content in items available in 2012 to new items added in each of the next four years. Full-service restaurants showed the largest reduction in sodium on new items (163 mg), followed by fast-food (83 mg) and fast-casual (19 mg) eateries.

The team’s findings are reported online in the American Journal of Preventive Medicine.

The average American aged 19-50 consumes more than 3,700 mg of sodium. The excess has been linked to high blood pressure, stroke and heart disease. Health experts have determined that a 1,200 mg drop in daily sodium intake could save as many as 92,000 lives and up to $25 million in health care costs annually.

Previous research has shown that 80 percent of our sodium consumption is from eating food prepared outside of the home. Studies also have found that one-third of adults and children eat fast food every day and nearly half of all food purchases are outside of the home. Therefore, reducing the sodium content of restaurant food could have benefits for Americans’ health, Wolfson said.

Nearly a decade ago, leading health organizations called for a National Salt Reduction Initiative, which sought to reduce sodium consumption by 25 percent from 2009 to 2014. This initiative may have motivated many restaurants to offer healthier food options, but Wolfson said voluntary efforts have not been enough.

“Requiring large chain restaurants to add sodium warning labels to their menus could be an important tool to incentivize restaurants to reduce the sodium content of their food, and are an important information tool for consumers,” she said. “Federal regulations requiring warning labels are not likely at this time, but states and cities could certainly implement these regulations.

“State and local labeling regulations, in combination with public awareness campaigns to increase consumer awareness about the dangerously high sodium content of restaurant food could increase consumer demand for lower sodium options and spur chain restaurants to voluntarily reduce the sodium in their food.”

In the meantime, Wolfson said consumers should be aware that many foods have hidden sodium, and they should ask restaurants for information on what is in the meals they are buying. It may not be printed on the menu but most chain restaurants have nutrition information available.

And she has one other tip for consumers.

“Restaurant food is notoriously high in sodium—it’s one reason it tastes so good,” she said. “Switching from restaurant meals to more meals prepared at home made with fresh or minimally processed ingredients will help reduce the sodium in your diet.”

More information: