IOM: No Clear Benefits To Slashing Sodium Intake to 1500 mg/Day

Shelley Wood

May 15, 2013

WASHINGTON, DC — The US Institute of Medicine (IOM), asked by the US Centers for Disease Control and Prevention (CDC) to review the evidence for limiting sodium intake, has reached a controversial conclusion: there is no consistent evidence to support lowering sodium intake in the general population to levels of 1500 mg/day[1,2].

Moreover, the report concludes, there is no scientific evidence to support treating certain population subgroups any differently from the rest of the US population.

The report, issued yesterday, was blasted by the American Heart Association (AHA), which claimed the report was "incomplete," failing to take into account the vast evidence linking high blood pressure to excess sodium consumption[3].

The AHA recommends that Americans consume no more than 1500 mg of sodium per day; federal guidance uses a cutoff of 2300 mg per day, except for certain subgroups that should aim for the 1500-mg target: people over 50, non-Hispanic blacks, and anyone with diagnosed hypertension, prehypertension, diabetes, congestive heart failure, or chronic kidney disease.

The IOM report does agree that there is a "positive relationship" between higher sodium intake and risk of CVD. But it says that the existing research does not conclusively establish that lowering sodium below 2300 mg/day increases or decreases the risk of heart disease, stroke, or all-cause mortality. Moreover, "the evidence on both benefit and harm is not strong enough" to indicate that so-called high-risk subgroups should lower their sodium intake to 1500 mg/day, the report concludes.

"Studies make clear that looking at sodium's effects on blood pressure is not enough to determine dietary sodium's ultimate impact on health," writing committee chair Dr Brian Strom (University of Pennsylvania Perelman School of Medicine) said in a press statement. "Changes in diet are more complex than simply changing a single mineral. More research is needed to understand these pathways."

The AHA, however, points out that both the World Health Organization, as well as the prior IOM report, determined that blood pressure was a suitable proxy for hard cardiovascular disease outcomes. A review of the evidence linking high blood pressure to heart disease and stroke is missing from the IOM's latest report, the AHA notes.

The lack of studies linking sodium intake to increased risk of hard events has long been a topic of hot debate. A number of modeling studies have estimated that excess salt intake shoulders the blame for millions of deaths worldwide, as well as soaring healthcare costs.


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