Lowering sodium intake, a drumbeat of doctors’ efforts to improve patient health, may have the opposite effect if taken to the extreme, scientists said.
U.S. dietary guidelines to reduce sodium intake to 1,500 milligrams a day for certain people aren’t supported by enough scientific evidence, an Institute of Medicine panel said in a report yesterday. Studies reviewed by the panel didn’t prove health outcomes improved when salt consumption was cut to that level.
“Lowering sodium intake too much may actually increase a person’s risk of some health problems,” Brian Strom, the panel chairman and a public health professor at the University of Pennsylvania Perelman School of Medicine, said in a statement. The studies still “support previous findings that reducing sodium from very high intake levels to moderate levels improves health.”
Adults consume an average 3,400 milligrams of salt each day. The U.S. recommends 2,300 milligrams for the general public and as low as 1,500 milligrams for those with high blood pressure, diabetes or chronic kidney disease, black people and people older than age 50. The American Heart Association, which advises 1,500 milligrams for everyone, challenged the report.
“The report is missing a critical component -- a comprehensive review of well-established evidence which links too much sodium to high blood pressure and heart disease,” said Nancy Brown, chief executive officer of the association.
In addition, studies that don’t show a benefit on heart disease or adverse effects were conducted on sick people, the Dallas-based association said in a statement.
The IOM panel said it looked at studies that measured health outcomes such as heart disease and death rather than high blood pressure as an indicator of heart disease.
“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,” Strom said. “Changes in diet are more complex than simply changing a single mineral. More research is needed to understand these pathways.”
The report recognizes that blood pressure is only one of many factors that should be considered when evaluating dietary changes, the Salt Institute, an Alexandria, Virginia-based trade group that represents companies including Morton Salt Inc., said in a statement. Morton Satin, vice president of science and research for the Salt Institute, praised the report’s caution against reducing sodium to 1,500 milligrams.
“The recognition by the IOM experts that such low levels may cause harm may help steer overzealous organizations away from reckless recommendations,” Satin said.
The panel’s report didn’t list what a healthy sodium range would be, and the authors said further research is needed on associations between lower levels of sodium and health outcomes.
The Institute of Medicine, the health arm of the Washington-based nonprofit National Academies, provides medical advice to policy makers and the public. The report was sponsored by the U.S. Centers for Disease Control and Prevention.