Dietary sodium and potassium consumption is associated with blood pressure levels. The objective of this study was to define a practical and low-cost method for the control of blood pressure by modification of these dietary cations in rural Chinese.
This study was a double-blind, randomized, controlled trial designed to establish the long-term effects of a reduced-sodium, high-potassium salt substitute (65% sodium chloride, 25% potassium chloride, 10% magnesium sulphate) compared to normal salt (100% sodium chloride) on blood pressure among high-risk individuals. Following a 4-week run-in period on salt substitute, participants were randomly assigned to replace their household salt with either the study salt substitute or normal salt for a 12-month period.
The mean age of the 608 randomized participants was 60 years and 56% of them were female. Sixty-four percent had a history of vascular disease and 61% were taking one or more blood pressure-lowering drugs at entry. Mean baseline blood pressure was 159/93 mmHg (SD 26/14). The mean overall difference in systolic blood pressure between randomized groups was 3.7 mmHg (95% confidence interval 1.6–5.9, P < 0.001). There was strong evidence that the magnitude of this reduction increased over time (P = 0.001) with the maximum net reduction of 5.4 mmHg (2.3–8.5) achieved at 12 months. There were no detectable effects on diastolic blood pressure.
Salt substitution produced a substantial and sustained systolic blood pressure reduction in this population, and should be actively promoted as a low-cost alternate or adjunct to drug therapy for people consuming significant quantities of salt.
*Authors listed in Acknowledgements.
Received 12 March, 2007
Revised 11 May, 2007
Accepted 4 June, 2007
Correspondence to Bruce Neal, The George Institute for International Health, University of Sydney, PO Box M201, Camperdown, Sydney, NSW2050, Australia Tel: +61 2 9993 4558; fax: +61 2 9993 4502; e-mail: firstname.lastname@example.org
or to Wu Yangfeng, The George Institute for International Health China, Room 1302, Tower B, Horizon Tower, No. 6 Zhichun Road, Haidian District, Beijing, 100088 PR China Tel: +86 10 8280 0577; fax +86 10 8280 0177; e-mail: email@example.com
Presentations of this study previously given:
(1) Li N, Wu Y, Barzi F, Yu X, Zhao L, Neal B. A low sodium, high potassium salt substitute substantially lowers blood pressure levels among high-risk individuals in rural northern China-The China Salt Substitute Study. Sixteenth European Meeting on Hypertension, 12–15 June 2006, Madrid, Spain (oral presentation).
(2) Li, N, Wu, Y, Barzi F, Yu, X, Zhao, L and Neal, B. A low sodium, high potassium salt substitute substantially lowers blood pressure levels among high-risk individuals in rural northern China. Heart Foundation Conference and Scientific Meeting. Cardiovascular Disease in the 21st Century: Shaping the future. 23–25 March 2006, Sydney, Australia (poster and oral presentation).
(3) Li N, Wu Y, Barzi F, Yu X, Zhao L, Neal B. A low sodium, high potassium salt substitute substantially lowers blood pressure levels among high-risk individuals in rural Northern China. American College of Cardiology 55th Annual Scientific Session in Atlanta, 11–14 March 2006 (oral presentation).
Trial registration: clinicaltrials.gov; Identifier: NCT00145756; URL: http://www.clinicaltrials.gov/ct/show/NCT00145756?order=1