MARCH 2010

Cutting your salt intake could significantly reduce your risk of stroke and cardiovascular disease, according to a new analysis. Researchers systematically reviewed the scientific literature and identified 13 studies of salt/ sodium involving a total of 177,025 participants. Pooling this data, the researchers found that a decrease in intake of 5 grams of salt a day—a little less than a teaspoon—was associated with a 23% lower rate of strokes and as much as a 17% lower risk of cardiovascular disease.

That level of salt reduction would amount to roughly cutting in half the typical intake in the American diet, estimated at about 10 grams daily. The US Department of Agriculture recommends limiting salt intake to 5.8 grams per day, while the World Health Organi zation calls for no more than 5 grams daily.

But the importance of cutting down on salt to reduce dietary sodium hasn’t really hit home with many consumers, experts say. And the food industry has resisted tougher regulations on salt content, even though more than 70% of the salt in the US diet comes from packaged foods, not the salt shaker.

Researchers Pasquale Strazzullo, MD, of the Federico II University of Naples, and colleagues said they hoped their findings put to rest any lingering doubts about the health effects of too much salt. “This meta-analysis shows unequivocally that higher salt intake is associated with a greater incidence of strokes and cardiovascular events,” they concluded.

In an accompanying editorial in the journal BMJ, Lawrence J. Appel, MD, MPH, of Johns Hopkins Meducal Institutions, commented that the importance of the association between excess salt intake and raised blood pressure— leading, in turn, to strokes and coronary heart disease—“cannot be overstated.”

Indeed, a report from market-research firm Mintel released at the same time as the Italians’ meta-analysis suggests the food industry may finally be getting the message. Mintel new-products expert Lynn Dornblaser predicted that sodium reduction in packaged foods is “poised as the next major health movement.” Unlike most trends toward healthier eating, Dornblaser added, “sodium reduction is being pushed by food companies and health organizations, not by consumers.” Nonetheless, Mintel forecasted that sodium reduction is “finally ready to take hold.” Food-industry giants that have recently announced sodium-reduction goals include ConAgra and Unilever.

Adding to the drumbeat of supporting scientific evidence, Dr. Straz - zullo and colleagues analyzed studies with a total of more than 11,000 strokes and other vascular events. They noted a wide variety in the results of individual studies both for stroke and cardiovascular disease. But when the data were combined, the connection between excess salt and greater stroke risk was clear: An average of about 5 grams higher salt intake per day was associated with a 23% higher relative risk of stroke. As salt intake went up, so did stroke risk.

The link between salt and cardiovascular disease was less dramatic—14% higher risk for an extra 5 grams of daily salt. But when one “outlier” study showing a significant risk reduction with greater salt intake was excluded, the association became significant (17%).

The researchers noted that studies with longer follow-up periods showed an even stronger relationship between salt intake and stroke risk, though not for total cardiovascular events. They also cautioned that the analysis likely underestimated the risk of too much salt because all the studies relied on only a single measurement of salt intake, while actual consumption varies widely from day to day.

TO LEARN MORE: BMJ, online before print; abstract at www.bmj.com/cgi/content/abstract/339/ nov24_1/b4567. Sodium Tipsheet: 10 Tips to Cut Back www.mypyramid.gov/downloads/TenTips/ SodiumTipsheet.pdf