When people check nutrition labels, they often look at fat and calories and ignore sodium, even though sodium has been linked to high blood pressure.
Clinical nutritionist Samantha Heller said on "Good Morning America" that even a health-conscious consumer could be eating hidden salt.
High blood pressure often doesn't cause obvious symptoms.
If it's left untreated, however, it can lead to heart attack and stroke. Of the 65 million Americans believed to have high blood pressure, about one-third don't know it.
Although the federal government recommends 2,300 mg of sodium a day, the average American takes in 4,000 mg of daily sodium, which is equivalent to more than three pounds of salt per year.
"Sodium in and of itself is not bad," Heller said. "It's an electrolyte and works with other nutrients in your body. Still, we eat too much."
Heller said that 75 percent of the sodium consumed was in processed food, not salt that people added themselves.
"Well, the main thing is that it doesn't have to taste salty for there to be sodium," she said. "For example, the grande Starbucks java chip Frappuccino® light blended coffee has 350 milligrams of sodium, and one Krispy Kreme chocolate iced cake doughnut has 320 mg. That's about 15 percent of your daily allowance."
"Also, cheese is always high in sodium, and any processed tomato products: tomato paste, tomato sauce, tomato juice. Unless it says 'low-sodium' on the label, it's got high sodium."
Starbucks and Krispy Kreme say they list nutritional information so that customers can make informed decisions.
Kraft, which owns Oscar Mayer, said it was currently looking for ways to reduce sodium in many of its products.
Heller said that any food with more than 480 mg per serving should be considered a high-sodium food.
It is not only salt that accounts for sodium, she said.
"It might say baking soda, baking powder, MSG or disodium phosphate," she said. "Those all are other names for sodium. Also, things that are smoked -- they've got sodium."
Heller recommended spices and herbs like cayenne pepper, wasabe or rosemary to season foods, and fresh salsa also adds a lot of flavor. She said salt was an acquired taste, but people could wean themselves off it.
"Be prepared that it's gonna be an adjustment," she said. "You just have to have some patience. Always go for low-sodium alternatives. Use fresh, unprocessed food and spices and low-sodium alternatives. You can get rid of hundreds of milligrams of sodium just by using the low-sodium alternative to things like tomato paste and soup."