16 August 2013 | News | By Bureau Report
Recent studies that examine links between sodium consumption and health outcomes support recommendations to lower sodium intake from the very high levels some Americans consume now, but evidence from these studies does not support reduction in sodium intake to below 2,300 mg per day, says a report from the Institute of Medicine, Washington. The report was sponsored by the Centers for Disease Control and Prevention.
Despite efforts over the past several decades to reduce dietary intake of sodium, a main component of table salt, the average American adult still consumes 3,400 mg or more of sodium a day – equivalent to about 1 ½ teaspoons of salt. The current dietary guidelines for Americans urge people between 14 to 50 to limit their sodium intake to 2,300 mg daily. Those 51 and above, African Americans, and people with hypertension, diabetes, or chronic kidney disease – groups that together make up more than 50% of the US population – are advised to follow an even stricter limit of 1,500 mg per day. These recommendations are based largely on a body of research that links higher sodium intakes to certain “surrogate markers” such as high blood pressure, an established risk factor for heart disease.
The expert committee that wrote the report reviewed recent studies that in contrast examined how sodium consumption affects direct health outcomes like heart disease and death. "These new studies support previous findings that reducing sodium from very high intake levels to moderate levels improves health," said committee chair Brian Strom, George S Pepper, Professor of Public Health and Preventive Medicine, at the University of Pennsylvania, Perelman School of Medicine. "But they also suggest that lowering sodium intake too much may actually increase a person’s risk of some health problems."
While cautioning that the quantity of evidence was less-than-optimal and that the studies were qualitatively limited by the methods used to measure sodium intake, the small number of patients with health outcomes of interest in some of the studies, and other methodological constraints, the committee concluded that:
The report does not establish a "healthy" intake range, both because the committee was not tasked with doing so and because variability in the methodologies used among the studies would have precluded it.
The recent studies suggest that dietary sodium intake may affect heart disease risk through pathways in addition to blood pressure. "These studies make clear that looking at sodium’s effects on blood pressure is not enough to determine dietary sodium’s ultimate impact on health," said Strom. "Changes in diet are more complex than simply changing a single mineral. More research is needed to understand these pathways."