NEJM: Even small salt reduction in U.S. would reduce CV events, medical costs

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Modest reductions in dietary salt could substantially reduce cardiovascular events and medical costs and should be a public health target in the U.S., according to a study in the Feb. 18 issue of the New England Journal of Medicine.

The U.S. diet is high in salt, with the majority coming from processed foods, according to the study authors, who added that reducing dietary salt is a “potentially important target” for the improvement of public health.

Kirsten Bibbins-Domingo, PhD, MD, from the University of California, San Francisco, and colleagues used the coronary heart disease (CHD) policy model to quantify the benefits of potentially achievable, population-wide reductions in dietary salt of up to 3 g per day (1200 mg of sodium per day). They estimated the rates and costs of cardiovascular disease in subgroups defined by age, sex and race and compared the effects of salt reduction with those of other interventions intended to reduce the risk of cardiovascular disease. Then, the researchers determined the cost effectiveness of salt reduction as compared with the treatment of hypertension with medications.

Reducing dietary salt by 3 g per day is projected to reduce the annual number of new cases of CHD by 60,000 to 120,000, stroke by 32,000 to 66,000 and MI by 54,000 to 99,000 and to reduce the annual number of deaths from any cause by 44,000 to 92,000, according to the authors.

All U.S. population segments would benefit, with blacks benefiting proportionately more, women benefiting particularly from stroke reduction, older adults from reductions in CHD events and younger adults from lower mortality rates, wrote Bibbins-Domingo and colleagues. They said the cardiovascular benefits of reduced salt intake are on par with the benefits of population-wide reductions in tobacco use, obesity and cholesterol levels.

A regulatory intervention designed to achieve a reduction in salt intake of 3 g per day would save 194,000 to 392,000 quality-adjusted life-years and $10 billion to $24 billion in healthcare costs annually, according to the researchers. “Such an intervention would be cost-saving even if only a modest reduction of 1 g per day were achieved gradually between 2010 and 2019 and would be more cost-effective than using medications to lower blood pressure in all persons with hypertension,” they wrote.

The authors also noted that even if the federal government were to bear the “entire cost of a regulatory program designed to reduce salt consumption, the government would still be expected to realize cost savings for Medicare, saving $6 to $12 in healthcare expenditures for each dollar spent on the regulatory program.”

Bibbins-Domingo and colleagues concluded that their findings support “urgent call to action that will make it possible to achieve these readily attainable cardiovascular benefits.”

However, in the accompanying editorial, Lawrence J. Appel, MD, and Cheryl A.M. Anderson, PhD, from Johns Hopkins University in Baltimore, questioned how achievable a reduction of 3 g per day is. They explained that the "mean salt intake in the U.S. is extremely high in most age groups, including children, and is well above the current daily recommended upper limit of 5.8 g (2300 mg of sodium)."

As a result, Appel and Andersen recommended two complementary strategies that could be used to lower salt intake: a public health approach, in which food manufacturers reduce levels of salt in processed and prepared foods and an individual approach, which relies on each person to select and prepare foods with little or no salt.