Lower Levels of Sodium Intake and Reduced Cardiovascular Risk: The Challenge to Achieve Lower Sodium Recommendations
It is well known that sodium intake is directly related to the development of high blood pressure. In two recent meta-analyses, higher sodium intake was also related to greater risk of incident stroke and CVD;1,2 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 non-significant associations of sodium reduction with lower CVD risk and total mortality over 6 or more 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 followup.6 In this issue of Circulation, Cook and colleagues reported a lower risk of CVD or CVD mortality among study participants with lower urinary sodium (<2300 mg/24 hours) compared to higher levels (3600 to <4800 mg/24 hours).7 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 commonly been represented by a 'spot urine' or overnight urine collection which is not an accurate estimate of usual sodium intake and thus, previously published study results may be biased.5,9,10
- Received January 2, 2014.
- Accepted January 6, 2014.