A high sodium intake, especially when combined with a low potassium intake, is associated with an increased risk of cardiovascular disease (CVD) and mortality, according to a report in the July 11 issue of Archives of Internal Medicine, one of the JAMA/Archives journals.
According to background information in the article, previous trials and studies have demonstrated apparent associations between increased blood pressure and high sodium intake or low potassium intake. "Recently, several studies suggested that the ratio of sodium to potassium intakes represented a more important risk factor for hypertension and CVD than each factor alone," write the authors. "Examining the joint effects of sodium and potassium intakes on CVD risk is particularly important because most of the U.S. population consumes more sodium and less potassium daily than recommended."
Quanhe Yang, Ph.D., from the Centers from Disease Control and Prevention, Atlanta, and colleagues used data from the Third National Health and Nutrition Examination Survey Linked Mortality File. They selected the data from 12,267 participants for analysis based on dietary information, demographic characteristics and health history. The data set also included mortality status matched to the participants. The researchers analyzed the data to determine consumption of sodium and potassium, as well as the sodium-potassium ratio, and to further determine the relationship between these variables and the risk of all-cause mortality as well as CVD and ischemic heart disease (IHD) mortality.
After an average follow-up period of 14.8 years, 2,270 of the participants had died; 825 of the deaths were attributed to CVD and 433 to IHD. Researchers found several characteristics associated with a higher sodium-potassium ratio, including male sex, younger age, status as a smoker and ethnic background. After adjusting for other variables, a higher sodium intake was related to increased all-cause mortality, and a higher potassium intake was associated with a lower mortality risk. The risk of CVD and IHD was significantly associated with a higher sodium-potassium ratio.
"In summary, our findings indicate that higher sodium-potassium ratio is associated with significantly increased risk of CVD and all-cause mortality in the general US population," write the authors. "Public health recommendations should emphasize simultaneous reduction in sodium intake and increase in potassium intake."
Commentary: Sodium and Potassium Intake-Mortality Effects and Policy Implications
An accompanying commentary by Lynn D. Silver, M.D., M.P.H., and Thomas A. Farley, M.D., M.P.H., from the New York City Department of Health and Mental Hygiene, takes the findings of Yang and colleagues into consideration. "This article strengthens the already compelling evidence of the relationship between sodium intake and mortality," they write. Silver and Farley detail large-scale efforts to reduce sodium consumption and raise potassium consumption.
The authors recommend that such efforts continue, and that potassium content further be added to the Nutrition Facts panels of food labels. Silver and Farley also call for the creation of a nutritional database that would help consumers and scientists better learn about the nutrient content of the U.S. food supply. "It is crucial," they conclude, "that we understand the interplay of sodium and potassium in the diet and how to optimize intake in an increasingly processed food supply without generating harm."
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