Frontline Medical News, 2013 May 14, K Blum
Americans should lower sodium consumption to optimize their health – but not below levels of 2,300 mg per day, according to a new report from the Institute of Medicine.
People aged 51 years and older, African-Americans, and those with hypertension, diabetes, or chronic kidney disease can follow the same advice, according to authors of the report, released during a webinar May 14.
That recommendation is a departure from the current Dietary Guidelines for Americans from the U.S. Department of Health and Human Services, which recommends that these higher-risk groups limit sodium intake to 1,500 mg daily. The HHS guidelines recommend that most other people aged 14-50 years limit sodium intake to 2,300 mg per day.
On average, Americans consume 3,400 mg or more of sodium a day (equivalent to 1.5 teaspoons of salt), despite efforts over the past few decades to reduce sodium consumption, according to the IOM report, which was sponsored by the Centers for Disease Control and Prevention.
“We found no consistent evidence to support an association between sodium intake and either a beneficial or adverse effect on most direct health outcomes,” said Dr. Brian L. Strom, George S. Pepper Professor of Public Health and Preventive Medicine at the University of Pennsylvania, Philadelphia, who chaired the committee that released the report.
The committee did not suggest an optimal target range for sodium consumption.
Dr. Strom and his colleagues reviewed medical studies from 2003 to 2012 that evaluated the direct impact of sodium intake on outcomes such as heart disease and death. Although the studies varied widely in the quality of their methodology and data collection, the report’s authors came to the following conclusions:
• There was a positive relationship between higher levels of sodium and risk of heart disease, consistent with previous research looking at sodium’s effects on blood pressure.
• There were insufficient data to determine if lowering sodium intake below 2,300 mg/day conferred any increase or decrease in the risk of heart disease, stroke, or death.
• Sodium intake of 1,840 mg/day or less may increase the risk of adverse health effects such as cardiovascular events or death among people with mid- to late-stage heart failure receiving aggressive treatment.
• Health outcomes studies provide little evidence about the effects of low sodium intake among those with diabetes, kidney disease, and heart disease, suggesting that people affected by these conditions could follow recommendations for the general public.
But the recommendations prompted calls for caution by some health experts.
The IOM report included “weak studies with numerous problems” and did not include evidence on the effects of sodium reduction on blood pressure, “a key determinant of health and the largest determinant of preventable mortality worldwide,” Dr. Lawrence Appel, director of the Welch Center for Prevention, Epidemiology, and Clinical Research at Johns Hopkins University, Baltimore, said in an interview.
Dr. Appel said he still supports the recommendations of the Dietary Guidelines, which he helped create. “Middle- and older-aged adults, African Americans, and patients with hypertension, diabetes, and chronic kidney disease are those at greatest risk for blood pressure–related heart disease and stroke,” he said, and they stand to benefit from keeping sodium levels to 1,500 mg/day or less.