SALT.

The best available evidence on how salt consumption affects our health comes from observational studies, in which groups of subjects are investigated to identify any correlations between usual sodium intake and subsequent heart attacks and strokes. Nine such studies, looking at a total of more than 100,000 participants who consume as much sodium as New Yorkers do, have had mixed results. In four of them, reduced dietary salt was associated with an increased incidence of death and disability from heart attacks and strokes. In one that focused on obese people, more salt was associated with increased cardiovascular mortality. And in the remaining four, no association between salt and health was seen.[...]Only one...rigorous clinical trial on salt intake has been reported so far, and it focused on patients with fairly advanced heart problems. As it turned out, the group that adhered to a lower sodium diet actually suffered significantly more cardiovascular deaths and hospitalizations than did the one assigned to the higher sodium diet.

It's also important to distinguish between table salt and preservative salt. The majority of salt in our diets comes not from the crystals we shake onto pasta but from processed foods that use sodium for its preservative effects. Often, these foods don't even taste particularly salty, but can deliver more than 50 percent of your daily sodium requirements.