Effects of salt substitute on pulse wave analysis among individuals at high cardiovascular risk in rural China: a randomized controlled trial

Abstract

Reduced-sodium, increased-potassium salt substitutes lower blood pressure but may also have direct effects on vascular structure and arterial function. This study aimed to test the effects of long-term salt substitution on indices of these outcomes. The China Salt Substitute Study was a randomized, controlled trial designed to establish the effects of salt substitute (65% sodium chloride, 25% potassium chloride, 10% magnesium sulfate) compared with regular salt (100% sodium chloride) on blood pressure among 600 high-risk individuals living in six rural areas in northern China over a 12-month intervention period. Data on central aortic blood pressure, aortic pressure augmentation (AUG), augmentation index (AIx), the differences of the peak of first and baseline waves (P 1 -P 0 ) and pulse wave reflection time (RT) were collected at randomization and at the completion of follow-up in 187 participants using the Sphygmocor pulse wave analysis system. Mean baseline blood pressure was 150.1/91.4 mm Hg, mean age was 58.4 years, 41% were male and three quarters had a history of vascular disease. After 12 months of intervention, there were significant net reductions in peripheral (7.4 mm Hg, P¼0.009) and central (6.9 mm Hg, P¼0.011) systolic blood pressure levels and central pulse pressure (4.5 mm Hg, P¼0.012) and correspondingly there was a significant net reduction in P 1 -P 0 (3.0 mm Hg, P¼0.007), borderline significant net reduction in AUG (1.5 mm Hg, P¼0.074) and significant net increase in RT (2.59 ms, P¼0.001). There were no detectable reductions in peripheral (2.8 mm Hg, P¼0.14) or central (2.4 mm Hg, P¼0.13) diastolic blood pressure levels or AIx (0.06%, P¼0.96). In conclusion, over the 12-month study period the salt substitute significantly reduced not only peripheral and central systolic blood pressure but also reduced arterial stiffness.

Effect of sodium and potassium supplementation on vascular and endothelial function: a randomized controlled trial

“…Previous studies showed no effect of potassium interventions on fasting AIx (15,39,40). One salt-substitution study (simultaneously reducing sodium and increasing potassium) showed significant improvements in measures of arterial stiffness (central pulse pressure and pulse wave reflection time) after 12 mo of intervention but did not see an effect on AIx (41).…”

The relationship between systolic and diastolic blood pressure: a clinically meaningful slope?

“…These data are in sharp contrast with the current literature, which shows a beneficial effect of salt restriction on arterial stiffness. 43,44 The authors provide no explanation for this puzzling finding. The examined population was very small, with approximately one dozen patients enrolled in each of the three studies.…”

Sodium and potassium intake present a J-shaped relationship with arterial stiffness and carotid intima-media thickness

“…Njroge JN et al [15] and Ferreira-Sae MC et al [16] found that carotid intima-media thickness (C-IMT) was slightly increased in subjects with higher levels of salt consumption. The results of Hu Jet al [17] indicated that reduced salt intake was accompanied by a decrease in both central and peripheral blood pressure, as well as central pulse pressure. He FJ et al [18] observed a small decrease in pulse wave velocity following initiation of a low-salt diet.…”