Researchers analyzed the salt in 2,000 types of bread in 32 countries. Here’s what they found.

What do you think has more salt: a slice of bread or a pack of potato chips?

It depends, but in some cases, the answer may surprise you.

Bread, it turns out, is the top contributor of dietary sodium in the US and many other countries around the world. And a big new analysis from the World Action on Salt and Health, based at Queen Mary University of London, helps us understand why.

For the report, a global team of researchers analyzed the salt content in 2,000 breads sold in 32 countries and regions. More than a third of the loaves exceeded the maximum salt target for bread set out by the UK: 1.13g of salt per 100g, or the equivalent of half a teaspoon of salt for about two slices of bread.

The US has no official target, but voluntary draft Food and Drug Administration guidance suggests manufacturers should aim for about the same levels. According to the Centers for Disease Control and Prevention, about nine in 10 kids and adults in the US exceed the daily limits for sodium consumption (2.3g, or one teaspoon’s worth).

Some of the products analyzed in the report — like the rosemary focaccia from Ace Bakery in Canada — were “saltier than seawater.” That loaf had more than a teaspoon’s worth of salt per 100g (or about two slices), exceeding the recommended daily sodium intake. A popular product from South Africa, Golden Crust’s toaster bread, had the most salt per serving among all white breads in the survey: 2.46g per 250g portion. That’s “more salt than four portions of McDonald’s fries,” the report stated.

Breads from the US didn’t fare much better. Among the saltiest: Pepperidge Farm’s Hearty Sliced white bread, which contained 1.4g salt per 100g or two slices. That means every slice, the Center for Science in the Public Interest has pointed out, carries as much sodium as a small bag of potato chips. Even Whole Food’s white sandwich bread rivaled a bag of potato chips, with 1.37g salt per 100g.

Overall, the researchers discovered flatbreads and whole-wheat breads tended to be saltier than other types, and mixed-grain breads had the lowest average salt content. (You can see more details about your favorite breads, and how they rank, here.) Bakers put sodium in packaged breads because it boosts the flavor and acts as a preservative.

“Bread is an essential staple food in many countries but is still a key source of salt in our diets due to the frequency with which we eat bread,” said Mhairi Brown, a nutritionist at World Action on Salt and Health, in a statement. “Globally we must do more to reduce salt intake, and a simple way to do this is to lower salt in our staple foods.”

The major reason salt is concerning for health is that too much of it can increase blood pressure, which can in turn increase risk for a heart disease and stroke.

To be sure, salt isn’t the only risk factor for high blood pressure. Genetics, exercise, bodyweight, alcohol consumption, stress, age, and overall diet play a role as well. And some people may be more sensitive to salt and its health effects than others. But researchers generally agree most people should aim to eat no more than one teaspoon per day. (For more detail, read here).

If you’re trying to cut back, you definitely want to look beyond the salt shaker. About 80 percent of the sodium Americans eat comes from salt that’s added to some of our most popular foods during processing, like store-bought bread, frozen pizza, and cold cuts. Avoiding these kinds of prepackaged foods and restaurant meals wherever possible will help reduce your sodium intake.

When you eat foods that you prepare yourself, you shouldn’t have to worry about sodium. As Norman Kaplan, a blood pressure researcher at the University of Texas Southwestern Medical Center, has told me, “If it’s fresh, you don’t have to worry about the sodium. The fact that nothing in nature is high in salt should tell people something.”

Of course, cooking fresh foods at home is not always possible at a time when many of us rely on quick, ready-made foods to get by. That’s why many public health officials continue to call on governments and industry to find ways of cutting salt during food processing.

The FDA is currently working to advance voluntary sodium reduction targets for the food industry, asking the food industry to commit to cutting sodium levels in packaged foods.

Until that happens, don’t forget to pay attention to the sodium in your bread. The new report is a reminder that not all breads are created equal, and the biggest salt contributor to the diet is probably lurking next to your butter knife.