The study recruited 450 participants aged 18 to 74 years old and from the Palo Alto, California; Birmingham, Alabama; and Minneapolis, Minnesota regions of the US, with subjects divided evenly among each location.
Participants were asked to keep daily records of their food intake for a four-day period, which was then reported to researchers during four telephone interviews.
Participants also had to provide samples of salt for the researchers to replicate the amount they had added to their food at home.
The results showed that the sodium intake was similar across all age groups, with participants consuming an average of 3,501 mg each day -- over 50 percent more than the recommended 2,300 mg.
The team also found that it was sodium added to food eaten outside of the home -- including restaurant meals and processed foods purchased in stores -- that was the main contributor to this high intake, accounting for 70.9 percent of daily sodium consumption and sodium found naturally in food the next highest accounting for 14.2 percent.
In contrast sodium from salt added during home cooking accounted for just 5.6 percent and sodium added at home was next highest at 4.9 percent.
The American Heart Association recommends a maximum of 2,300 milligrams (mg) of sodium a day, equivalent to 1 teaspoon of salt, however for nearly 70 percent of US adults, based on their age, race or ethnicity, or existing high blood pressure, the maximum recommendation is even lower, just 1500 mg/day.
"If you're aiming to limit your sodium intake to the recommended level of less than 2,300 milligrams per day, you'll need to choose foods wisely when grocery shopping and dining out," advised lead author Lisa J. Harnock, "For packaged foods, the nutrition fact panel may be useful in identifying lower sodium products, and for menu items diners can request sodium content information. Also, if you frequently add salt to food at the table or in home food preparation, consider using less."
The Institute of Medicine has already recommended trying to reduce salt intake by gradually decreasing sodium levels in commercially processed foods, making the suggestion back in 2010. The American Heart Association also agree that food companies and also restaurants must play their part in tackling the serious health issue, encouraging both to also reduce the sodium in their products and foods.
Another US study published just last month also found that those who cooked at home were healthier eaters than those who ate out more, with regularly eating home-cooked dinners associated with diets lower in calories, sugar and fat.
The results of the sodium research can be found published online in the American Heart Association's journal Circulation.