Subjects: Behavioral health
A meta-analysis performed by Italian scientists has shown that reducing salt intake by half in Westernized countries can reduce strokes by 23%, which amounts to about 1.25 million deaths, and reduce cardiovascular disease by 17% which amounts to nearly 3 million additional deaths per year.
Americans consume about 10 grams (or 2 teaspoons) of salt per day.
The World Health Organization recommends that dietary salt intake should be half that. The US Department of Agriculture recommends just under 6 grams per day.
To reach their astounding conclusions, Pasquale Strazzullo and colleagues at the University of Naples pooled data from 13 prospective studies published between 1966 and 2008. The analysis covered 177,000 subjects who sustained more than 11,000 strokes or cardiovascular events.
The extra power of the meta-analysis proved decisive in reaching the positive conclusions, since only 9 showed a direct positive link between sodium intake and the adverse events (of which only 4 reached statistical significance). Three actually showed a non-significant inverse relationship.
Studies featuring longer periods of follow-up appeared to strengthen the relationship between salt intake and stroke, although this was not the case for cardiovascular events.
The findings were not impacted by age, sex, and hypertension status.
In an accompanying editorial, Lawrence Appel of Johns Hopkins hailed the study as a “useful and welcome addition” to the confusing literature on the subject.
“At a minimum, Strazzullo and colleagues’ analyses should dispel any residual belief that salt reduction might be harmful (a canard resulting from misinterpretation of studies, often with flawed analyses),” Appel wrote.
Appel probably had in mind long-standing efforts by the food industry to oppose tougher public health policies on dietary salt intake, which have been largely successful because the above-mentioned studies had muddied the waters so completely.
The write-up is in the British Medical Journal.