COVENTRY, UNITED KINGDOM — A difference of 5 grams a day in habitual salt intake is associated with a 23% difference in the rate of stroke and a 17% difference in the rate of total cardiovascular disease, according to results of a meta-analysis of 13 studies involving 177,025 people from six countries, including the United States. The meta-analysis was published Nov. 24 in the British Medical Journal.

Higher salt intake is associated with significantly greater incidence of strokes and total cardiovascular events, with a dose-dependent association, said the researchers from the University of Naples Medical School in Naples, Italy, and Warwick Medical School in Coventry. A reduction in salt intake of 5 grams per day at the population level each year could avert about 1 ¼ million deaths from stroke and almost 3 million deaths from cardiovascular disease, according to the researchers.

Although the researchers said a voluntary approach may be helpful in reducing salt intake, they encouraged government regulation.

"One barrier to a more effective implementation of public health policies has been the historical opposition of the food industry, based on the arguments that the available evidence does not show significant benefits on hard end points at a population level from a moderate reduction in salt intake," they wrote. "Our study now clearly addresses those doubts."

The meta-analysis examined six studies from the United States, two from Finland, two from Japan, and one each from The Netherlands, Scotland and Taiwan. The 13 studies met the following criteria: published anywhere from January 1966 to December 2008; a prospective population study; assessed salt intake as baseline exposure; determined either stroke or cardiovascular disease prospectively as the outcome; followed participants for at least three years; included an adult population; and indicated the number of participants exposed and the rate or number of events in different categories of salt intake.

The habitual salt intake is close to 10 grams a day in most Western countries and higher in many Eastern European and Asian countries, according to the researchers. A reduction of 5 grams a day of salt would bring consumption close to a level of 5 grams a day recommended by the World Health Organization.

Worldwide there are more than 5.5 million deaths a year from stroke and close to 17.5 million deaths a year from cardiovascular disease, according to a recent report of the World Heart Federation. According to the meta-analysis, since the case fatality rates for stroke is estimated at one in three and those for cardiovascular disease is estimated one in five, a 23% reduction in the rate of stroke and a 17% overall reduction in the rate of cardiovascular disease attributable to a reduction in population salt intake could avert 1 ¼ million deaths from stroke and almost 3 million deaths from cardiovascular disease each year.