Trio of Studies Tackle Health Effects of Salt Consumption
Three studies recently published in The New England Journal of Medicine (NEJM) have answered the Institute of Medicine’s call for additional data on the effects of salt consumption on human health, raising questions about the relationships between sodium intake, blood pressure, cardiovascular events, and mortality.
Relying on the Prospective Urban Rural Epidemiology (PURE) cohort study that followed more than 150,000 adult participants from a selection of low-, middle- and high-income countries, two of the articles used urinary sodium and potassium excretion measurements to estimate dietary sodium consumption. One study reported that, despite previous research linking sodium intake to hypertension, the association between sodium and potassium excretion and blood pressure was “non-linear and most pronounced in persons consuming high salt diets, persons with hypertension, and older persons.” Andrew Mente, et al., “Association of Urinary Sodium and Potassium Excretion with Blood Pressure,” NEJM, August 2014. Looking at mortality and cardiovascular events, the second study based on PURE data apparently found that “an estimated sodium intake between 3 g per day and 6 g per day was associated with a lower risk of death and cardiovascular events than was either a higher or lower estimated level of intake.” Martin O’Donnell, et al., “Urinary Sodium and Potassium Excretion, Mortality, and Cardiovascular Events,” NEJM, August 2014.
In addition, a third study undertaken by the Global Burden of Diseases Nutrition and Chronic Diseases Expert Group (NutriCode) used data from surveys and published reports covering 66 countries to conclude that, in 2010, “1.65 million deaths from cardiovascular causes… were attributed to sodium consumption above a reference level of 2.0 g per day.” Dariush Mozaffarian, et al., “Global Sodium Consumption and Death from Cardiovascular Causes,” NEJM, August 2014. The study’s authors further noted that these results underestimate the burden of other diseases allegedly associated with salt consumption, including kidney disease and gastric cancer. Additional details about similar findings from NutriCode appear in Issue 477 of this Update.
“The NutriCode investigators should be applauded for a herculean effort in synthesizing a large body of data regarding the potential harm of excess salt consumption. However, given the numerous assumptions necessitated by the lack of high-quality data, caution should be taken in interpreting the findings of the study,” comments a concurrent NEJM editorial. “Taken together, these three articles highlight the need to collect high-quality evidence on both the risks and benefits of low-sodium diets.”
Issue 534
