Did you start your day yesterday with a breakfast sandwich, pop into Subway for lunch, have a burger for dinner—or otherwise consume anything placed between two slices of bread? If so, you were part of the approximately 49 percent of all Americans over 20 years old who eats one sandwich per day, a new study finds.

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In the past, nutrition researchers tended to lump sandwiches under a single heading. In this new study, however, USDA Agricultural Research Service scientists turned to data from a survey called “What We Eat in America,” which asked around 6,000 participants to go into detail about the content of their meals the previous day. Forty-nine percent of Americans, they found, had eaten at least one sandwich the previous day.

Given all of that sandwich eating, this type of meal makes up a significant portion of Americans' daily dietary intake. But quantifying exactly how sandwiches contribute to our diet isn't easy, since they can be so variable. Past studies calculated that sandwiches make up about four percent of daily sodium intake, the researchers report. But adjusting for specific sandwich contents significantly changed that calculation.

The researchers now estimate that sandwiches account for one-fifth of the nation's total daily sodium intake—or about 30 percent of the sodium a person who's not on a restricted diet needs to consume in a single day. In addition to having a higher daily sodium intake, sandwich eaters also consumed about 300 kilocalories more than people who didn't opt for sliced bread that day.

“Many sandwiches, such as burgers and franks, and common sandwich components, such as yeast breads, cheese, and cured meats, are among the top contributors not only to sodium but also to energy in the diets of adult Americans,” the researchers conclude in a statement. “Due to sandwiches’ frequent consumption and considerable contributions to sodium intake, substituting lower-sodium for higher-sodium ingredients in sandwiches could significantly impact sodium intakes.”