High Salt Intake Is Associated with BETTER Health

This study is a fascinating one. It is based on the NHANES data base, which is one of the most respected (if not the most respected) nutritional data bases in the country. What the study showed is the opposite of what we have been lead to believe medically. It showed that the lower the salt intake, the HIGHER the risk of death. Put differently, our advice to people to avoid salt is more likely to be harmful than helpful!

On the other hand, though there was no significant evidence that salt was harmful, the evidence for a low salt diet being harmful was modest, so if people want to avoid salt it probably won't hurt them too much. The possibility of a low salt diet being harmful was also likely affected by more people in the low salt diet group having high blood pressure, so it may have been the underlying high blood pressure which caused the higher death risk (i.e., people with high blood pressure were told by their doctors to be on low salt diets and this could be a "confounding variables" that makes people misinterpret the data. The low salt didn't kill them, but rather it was their earlier high blood pressure).

Bottom line—Enjoy yourself! Eat the amount of salt that your body wants and don't worry about it (if you don't have high blood pressure or heart failure).

Abstract

BACKGROUND: Sodium restriction is commonly recommended as a measure to lower blood pressure and thus reduce cardiovascular disease (CVD) and all cause mortality. However, some studies have observed higher mortality associated with lower sodium intake.

OBJECTIVE: To test the hypothesis that lower sodium is associated with subsequent higher cardiovascular disease (CVD) and all cause mortality in the Third National Health and Nutrition Examination Survey (NHANES III). DESIGN: Observational cohort study of mortality subsequent to a baseline survey.

PARTICIPANTS: Representative sample (n=8,699) of non-institutionalized US adults age !30, without history of CVD events, recruited between 1988-1994.

MEASUREMENTS AND MAIN RESULTS: Dietary sodium and calorie intakes estimated from a single baseline 24-h dietary recall. Vital status and cause of death were obtained from the National Death Index through the year 2000. Hazard ratio (HR) for CVD mortality of lowest to highest quartile of sodium, adjusted for calories and other CVD risk factors, in a Cox model, was 1.80 (95% CI 1.05, 3.08, p=0.03). Non-significant trends of an inverse association of continuous sodium (per 1,000 mg) intake with CVD and all-cause mortality were observed with a 99% CI of 0.73, 1.06 (p=0.07) and 0.86, 1.04 (p=0.11), respectively, while trends for a direct association were not observed.

CONCLUSION: Observed associations of lower sodium with higher mortality were modest and mostly not statistically significant. However, these findings also suggest that for the general US adult population, higher sodium is unlikely to be independently associated with higher CVD or all-cause mortality.

References:

Hillel W. Cohen, DrPH, MPH, Susan M. Hailpern, MS, DrPH, and Michael H. Alderman, MD.; Sodium Intake and Mortality Follow-Up in the Third National Health and Nutrition Examination Survey (NHANES III). J Gen Intern Med. DOI: 10.1007/s11606-008-0645-6