The 200-page report* - which will likely prove controversial given that the Dietary Guidelines for Americans currently advise large sub-sectors of the US population to consume no more than 1,500mg/day - says there is not sufficient evidence to determine that lowering intakes below 2,300mg increases or decreases the risk of heart disease, stroke, or all-cause mortality.
Evidence is not strong enough to indicate that subgroups should be treated differently from the general population
It also noted that low sodium intake may lead to risk of adverse health effects among people with mid- to late-stage heart failure receiving aggressive treatment, and that there is limited evidence of an association between low sodium intake and health outcomes in people with diabetes, kidney disease, heart disease, hypertension or borderline hypertension; those 51 years of age and older; and African Americans.
It added: “The evidence on both the benefit and harm is not strong enough to indicate that these subgroups should be treated differently from the general US population. Thus, the evidence on direct health outcomes does not support recommendations to lower sodium intake within these subgroups to or even below 1,500 mg daily.”
Currently, Americans typically consume more than 3,400mg sodium a day, which is way above the maximum levels recommended in the Dietary Guidelines, which stipulate 2,300mg/day for most people, and 1,500mg for people aged 51+, all African Americans, plus anyone with hypertension, diabetes, or chronic kidney disease.
CSPI: Getting down to 2,300mg/day will be ‘nearly impossible’ unless the government mandates reductions
However, the report should not get the food industry off the hook, said the Center for Science in the Public Interest, which published research on Monday showing that industry sodium reduction efforts have been patchy and inconsistent.
“As the IOM itself stated in 2010”, said the CSPI, “urgent government action, including mandatory limits on salt in packaged foods, is required to help Americans bring their sodium consumption down to safe levels.
“Getting down to 2,300 will be nearly impossible until the government phases in reasonable limits on the sodium content of foods.”
Whether we aim for 2,300 or 1,500mg a day is irrelevant until we move down out of the red zone
Meanwhile, the committee did not determine whether the safest intake is below 2,300mg or below 1,500mg, it added.
“What the committee failed to emphasize is that most Americans are deep in the red zone, consuming 3,500 to 4,000mg of sodium a day.
“It’s clear that those excessive levels increase the risk of high blood pressure, heart attacks, and strokes. Whether we aim for 2,300 or 1,500mg a day is irrelevant until we move down out of the red zone.”
Meanwhile, the Grocery Manufacturers Association (GMA), welcomed the report.
Dr. Leon Bruner, Chief Science and Regulatory Affairs Officer said: “We are very pleased by the committee’s finding that there is insufficient scientific evidence to support a lowering of daily sodium intake levels to 1,500mg. We also note with interest the Committee’s acknowledgement of the new research pointing to possible adverse health effects in some populations from consuming too little sodium.
“Reducing sodium in products without negatively affecting consumer acceptance must be taken into consideration, because a ‘healthy food’ will not promote health if it is not purchased or eaten."
The debate: How low should we go?
The merits of population-wide sodium reduction are debated at length in submissions to the recent FDA/FSIS probe into sodium reduction strategies, with the American Heart Association arguing that there is “overwhelming evidence” to support population-wide sodium reduction efforts, and the GMA arguing that new data challenges “the conventional wisdom that sodium reduction will universally lead to health-promoting outcomes”.
One such study is a review by The Cochrane Library published in 2011 (click here), which concluded that “cutting down on the amount of salt has no clear benefits in terms of likelihood of dying or experiencing cardiovascular disease”.
Responding to the latest IOM report, American Heart Association CEO Nancy Brown said: "While the AHA commends the IOM for taking on the challenging topic of sodium consumption, we disagree with key conclusions. 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.”
She added: "The American Heart Association has meticulously reviewed scientific research and recommends that all Americans eat no more than 1,500 mg a day of sodium."
*To put together its new report, the IOM established a committee of 12 members with expertise in nutrition, cardiovascular disease, hypertension, diabetes, kidney disease, epidemiological studies, clinical trial design and data analysis, biostatistics, and evidence-based reviews. They focused on research published between 2003 and 2012, but described the quantity and quality of relevant studies as "less than optimal".
To read their report click here.