Nutrition expert Marion Nestle talks to Scientific American about how researchers in "just the past few months" have published "seemingly contradictory studies showing that excess sodium in the diet leads to heart disease, reduces your blood pressure, or has no effect at all." The interview opens with a stark reality:
[I]t's impossible to put a population of people on a low-salt diet. Roughly 80 percent of the salt in the American food supply is in foods before people eat them—either in processed food or in restaurant food. Because so much salt is added to the food supply and because so many people eat out, it's impossible to find a population of people who are eating a low-salt diet. They basically don't exist. In the one comparative epidemiological study they did some years ago—the Intersalt study—they managed to find two populations of people in remote areas of the jungle someplace who weren't eating a lot of processed foods and who weren't eating in restaurants.
Nestle adds, "Campbell's soup, for example, just announced yesterday that [they] can't sell low-sodium soups and so they're adding salt back."