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I'm Rob Logan, Ph.D. senior staff National Library of Medicine for Donald Lindberg, M.D, the Director of the U.S. National Library of Medicine.
A recent report from the U.S. Institute of Medicine (IOM) suggests there is insufficient evidence to support public health warnings that adults should limit their salt intake to about one teaspoon, or 2,500 milligrams a day.
The IOM report counters prevailing recommendations from some other medical organizations, such as the American Heart Association, that very low salt intake helps control blood pressure, which in turn lowers the risk of a stroke and a heart attack. While the IOM explained the low salt guidance is based on sound clinical
Specifically, a 2011 study of 28,550 middle aged and older persons with elevated blood pressure found high and low levels of salt increased their risk of heart attack, stroke, congestive heart failure, and death from heart disease. The low salt levels assessed in the study (that increased health risks) were similar to the current salt intake guidelines. The high salt levels were more than 7,000 milligrams a day.
The IOM report noted the 2011 study was among the first to assess salt consumption by urinalysis, which provides a more precise measure of salt intake than previous research. In addition, the study was among the first to evaluate the direct impact of salt on other biomedical and health measures instead of solely measuring how salt intake levels are associated with increased blood pressure. Instead of inferring that the frequency of heart attacks, stroke, congestive heart failure, hospitalizations and death occurred as a result of higher blood pressure and salt intake levels, the research cited by the IOM measured salt intake’s direct clinical impacts for the first time — and inspired a reconsideration of the salt dietary recommendations the IOM made in 2005.
Among other recent research, the IOM report cited a study from Italy that found adults with moderate to severe congestive heart failure (who reduced their dietary salt to low levels) experienced three times the rate of hospital readmissions and twice as many deaths compared to a higher salt intake group. While the number of participants in the Italian study was small (232 adults), the study’s findings are consistent with other, recent international research.
Brian Strom M.D., chair of the IOM committee that issued the report, told the New York Times (and we quote): ‘As you go below the 2,300 [salt intake] mark, there is an absence of data in terms of benefit and there begin to be suggestions in subgroup populations about potential harms’ (end of quote).
While the IOM report questions the clinical benefits of low salt intake, the report does not specify how much salt adults should consume daily. The IOM report also does not recommend the optimal amount of salt in one’s diet. The report notes these issues should be evaluated by new research that follows the aforementioned model established in recent salt, diet, and health studies.
In a story following the release of the report, the New York Times noted the IOM’s recommendations stunned many of the organizations and researchers who advocate a very low salt diet. The director of nutrition at the Center for Science in the Public Interest told the Times (and we quote): ‘It would be a shame if this report convinced people that salt doesn’t matter’ (end of quote).
However, other scientists told the Times the conflicting new recommendations may be associated with the differences in the more rigorous, different research methods used in recent studies.
Meanwhile, MedlinePlus.gov’s dietary sodium health topic page provides background information about the amount of salt in selected foods (provided by the U.S. Department of Agriculture) in the ‘nutrition’ section. A website from the American Heart Association (available in the ‘related issues’ section) provides a guide to the amount of salt in processed foods.
A list of salt substitutes in foods and cooking (from NIH MedlinePlus magazine) is available within the ‘MedlinePlus magazine’ section of MedlinePlus.gov’s dietary sodium health topic page.
MedlinePlus.gov’s dietary sodium health topic page also contains links to the latest pertinent journal research articles, which are available in the ‘journal articles’ section. Links to related clinical trials that may be occurring in your area are available in the ‘clinical trials’ section. From the dietary sodium health topic page, you can sign up to receive email updates with links to new information as it becomes available on MedlinePlus.
To find MedlinePlus.gov’s dietary sodium health topic page, just type ‘salt’ in the search box at the top of MedlinePlus.gov’s home page. Then, click on ‘Dietary sodium (National Library of Medicine).’ MedlinePlus.gov also has health topic pages devoted to high blood pressure, as well as food and nutrition.
It will be interesting to see if the recommendations in the IOM’s guidelines are adopted by other public health and medical organizations. The IOM suggests the issue might be settled with more comprehensive and rigorous research that the report suggests should continue in the future.
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