Dose-response relation between dietary sodium and blood pressure: a meta-regression analysis of 133 randomized controlled trials

Abstract

Background The projected reduced mortality effect of reduced sodium intake in model-based studies conflicts with the observed increased mortality associated with low sodium intake in population studies. This may reflect an overestimation of the dose-response relation between sodium reduction (SR) and blood pressure (BP) used in mortality modeling studies. Objectives The present meta-regression analysis sought to estimate the dose-response relations between SR and BP in study groups with mean BP above or below the 75th percentile of the general population. Methods Based on a literature search from 1 January 1946 to 11 April 2018, we identified 133 randomized controlled trials allocating healthy or hypertensive individuals to SR or usual sodium intake. Multivariable regression analyses of the mean SR versus the mean blood pressure effect adjusted for effect modifiers were performed. Results In study groups with mean BP above the 75th percentile [131/78 mm Hg systolic BP (SBP)/diastolic BP (DBP)], there was strong evidence of a linear dose-response relation between SR and BP. For SBP, the dose-response relation was −7.7 mm Hg/100 mmol SR (95% CI: −10.4, −5.0), and for DBP it was −3.0 mm Hg/100 mmol SR (95% CI: −4.6, −1.4). In study groups with mean BP ≤ 131/78 mm Hg, the relation between SR and BP was weak. For SBP it was −1.46 mm Hg/100 mmol SR (95% CI: −2.7, −0.20) and for DBP it was: −0.07 mm Hg/100 mmol SR (95% CI: −1.5, 1.4). Conclusions Only study groups with a BP in the highest 25th percentile of the population showed a clinically significant drop in BP with SR. The policy of lowering dietary sodium intake in the general population may need to be reframed to target patients with hypertension. This study was registered at PROSPERO 2015 as CRD42015017773.

Dietary Sodium Intake and Food Sources among Chinese Adults: Data from the CNNHS 2010–2012

“…Previous research, which consisted of a sample of Chinese adults (n = 6072) has already shown a concerning excessive sodium intake and an average consumption of sodium of 5.4 g/day [22]. Sodium maintains blood pressure, while consuming an excessive amount of sodium increases the risk of hypertension and NCD [4,24,25]. Although a recent study has shown that sodium consumption has been declining since 1982 in China [10], there are still some gaps comparing with the recommendations of the WHO [1].…”

Salt need needs investigation

“…The determinants of our excessive salt appetite have been scarcely researched and, consequently, are scarcely understood (14)(15)(16)(17)(18) . Research has been primarily into the consequences of salt intake, primarily comprising large-scale studies, which have engendered the consensus that salt is toxic, along with a nuanced contention that it is less so (7,(9)(10)(11)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27) .…”

“…Therefore, it is moot whether reduction is intervention-related any more than the parallel decrease in total energy intake, to which Na intake is inextricably linked (45,46) . Further, failures and contradictory data for the same countries in line with global increases or stability have also been reported (14,(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)42,(47)(48)(49)(50)(51) .…”

“…Excess salt intake has been related to many severe diseases, and yet it is uncertain how its use can be limited because too little salt may also contribute to ill health. People and communities differ so much that epidemiological studies, the mainstay of the Na-disease correlation, may swamp diversity, which may range from strong positive relationships to none or inverse relationships, even within the same study (19,(25)(26)(27)41,42,(52)(53)(54) . A J-shaped curve has been proposed to account best for the data (19) .…”

Letter to the editor on “Potential use of salt substitutes to reduce blood pressure”

“…5 There is also emerging evidence that salt reduction strategies are most effective when targeted to those in the highest quartile of intake and not the general population. 6 Second, the statement by the authors that "use of salt substitutes as a public health intervention warrants consideration as part of policy recommendations" is of great concern to us. Salt substitutes are one potential public health intervention to reduce sodium intake and increase potassium intake.…”