Not only is this bad for consumer health - according to the Center for Science in the Public Interest (CSPI), it is also unnecessary.
"Some brands of processed foods have sodium levels that are off the charts compared with other brands in the same category," said CSPI executive director Michael F. Jacobson.
"Excess sodium in the diet causes tens of thousands of preventable heart attacks and strokes each year. This salt assault is probably good for funeral directors and coffin makers, but it is a disaster for shoppers and restaurant patrons."
The CSPI argues that the huge disparities between brands show that many companies could easily achieve significant reductions without sacrificing taste.
Salt content is becoming a major battleground within the food sector. While there is no question that salt consumption in the American diet needs to be reduced - one in three Americans regularly consumer more salt than is recommended - many companies argue that consumer taste demands high salt levels.
Certainly, salt has a number of distinct characteristics that make it extremely attractive to food makers. Apart from being the world's oldest preservative, it can block bitterness in foods, and humans have an innate liking of salt, related to a specific body need, that makes salty snacks attractive.
The problem is that too much salt is bad for you, and that it is difficult to replicate. Potassium chloride-based sodium substitutes are only so good. Organizations such as the CSPI believe that the answer is simple: cut back on salt levels in processed food.
"Because salt is in so many foods at such high levels, it is virtually impossible for people to follow health authorities' advice to cut way back on sodium, particularly when packaged foods and restaurant foods make up such a big part of Americans' diets," said Jacobson.
"Food companies should use less salt across the board, but especially in the products that have the most. Why not put consumers in the driver's seat, and let them decide for themselves how much salt to add?"
The organization analyzed the labels of more than 500 food items in 20 categories and ranked them according to sodium content. For each product, CSPI calculated how much more sodium it had than the product with the least sodium in the category.
For instance, among brands of diced canned tomatoes, CSPI says that Hunt's Original has almost twice as much sodium (310 milligrams per 100 grams of product) as Contadina Roma Style (160 mg per 100 g). However, Contadina Roma Style tomato paste has more than three times as much sodium (910 mg per 100 g) as Hunt's (270 mg per 100 g).
In addition, many frozen or processed poultry and pork is marinated or otherwise processed in a sodium-rich solution. As a result, some brands of pork spareribs (Hormel, say) might have three-and-a-half times as much sodium as what USDA says spareribs naturally have (290 mg vs. 80 mg per 100 g).
According to CSPI, processed foods and restaurant foods contribute about 80 percent of the sodium in Americans' diets. Americans now consume about 4,000 milligrams of sodium per day - about twice the recommended amount.
As a result, the organization is urging Congress to create a new Division of Sodium Reduction within the FDA that could encourage food companies to use less salt. In the United Kingdom, where salt reduction has been a major priority for that country's Food Standards Agency, some food products, such as Kraft's Lunchables, have less sodium there than they do in the United States.