Lower Levels of Sodium Intake and Reduced Cardiovascular Risk

It is well known that sodium intake is directly related to the development of high blood pressure. In 2 recent meta-analyses, higher sodium intake was also related to greater risk of incident stroke and cardiovascular disease (CVD)2; however, whether lower sodium intake reduces risk of CVD is not clear.3 One meta-analysis of 7 clinical trials originally designed to test the effectiveness of sodium reduction on blood pressure found nonsignificant associations of sodium reduction with lower CVD risk and total mortality over ≥6 months of follow-up.4 In observational studies of diverse populations, a J-shaped relation between sodium intake (or urinary sodium excretion) and risk of CVD has been reported.5,6 In contrast, study participants assigned to a sodium reduction intervention had a lower risk of CVD over several years of follow-up.6 In this issue of Circulation , Cook and colleagues7 reported a lower risk of CVD or CVD mortality among study participants with lower urinary sodium (<2300 mg/24 h) than among those with higher levels (3600 to <4800 mg/24 h). Although the current study was not originally designed to test the effectiveness of lower sodium intake on CVD risk, multiple 24-hour urine samples, the “gold standard” measure of sodium intake, were used to characterize usual sodium intake.8 In most observational studies, sodium intake has been represented by a “spot urine” or overnight urine collection, which is not an accurate estimate of …