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School based education programme to reduce salt intake in children and their families (School-EduSalt): cluster randomised controlled trial

BMJ 2015; 350 doi: https://doi.org/10.1136/bmj.h770 (Published 18 March 2015) Cite this as: BMJ 2015;350:h770
  1. Feng J He, senior research fellow1,
  2. Yangfeng Wu, professor of epidemiology234,
  3. Xiang-Xian Feng, professor of epidemiology5,
  4. Jun Ma, professor6,
  5. Yuan Ma, PhD student123,
  6. Haijun Wang, professor6,
  7. Jing Zhang, research fellow2,
  8. Jianhui Yuan, professor of nutrition5,
  9. Ching-Ping Lin, global health fellow27,
  10. Caryl Nowson, professor of nutrition and ageing8,
  11. Graham A MacGregor, professor of cardiovascular medicine1
  1. 1Wolfson Institute of Preventive Medicine, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, UK
  2. 2George Institute for Global Health at Peking University Health Science Center, Beijing, China
  3. 3Department of Epidemiology and Biostatistics, Peking University School of Public Health, Beijing, China
  4. 4Peking University Clinical Research Institute, Beijing, China
  5. 5Changzhi Medical College, Shanxi, China
  6. 6Institute of Child and Adolescent Health, Peking University Health Science Center, Beijing, China
  7. 7University of Michigan Medical School, Ann Arbor, MI, USA
  8. 8School of Exercise and Nutrition Sciences, Deakin University, Geelong, Australia
  1. Correspondence to: F He f.he{at}qmul.ac.uk
  • Accepted 9 January 2015

Abstract

Objective To determine whether an education programme targeted at schoolchildren could lower salt intake in children and their families.

Design Cluster randomised controlled trial, with schools randomly assigned to either the intervention or control group.

Setting 28 primary schools in urban Changzhi, northern China.

Participants 279 children in grade 5 of primary school, with mean age of 10.1; 553 adult family members (mean age 43.8).

Intervention Children in the intervention group were educated on the harmful effects of salt and how to reduce salt intake within the schools’ usual health education lessons. Children then delivered the salt reduction message to their families. The intervention lasted for one school term (about 3.5 months).

Main outcome measures The primary outcome was the difference between the groups in the change in salt intake (as measured by 24 hour urinary sodium excretion) from baseline to the end of the trial. The secondary outcome was the difference between the two groups in the change in blood pressure.

Results At baseline, the mean salt intake in children was 7.3 (SE 0.3) g/day in the intervention group and 6.8 (SE 0.3) g/day in the control group. In adult family members the salt intakes were 12.6 (SE 0.4) and 11.3 (SE 0.4) g/day, respectively. During the study there was a reduction in salt intake in the intervention group, whereas in the control group salt intake increased. The mean effect on salt intake for intervention versus control group was −1.9 g/day (95% confidence interval −2.6 to −1.3 g/day; P<0.001) in children and −2.9 g/day (−3.7 to −2.2 g/day; P<0.001) in adults. The mean effect on systolic blood pressure was −0.8 mm Hg (−3.0 to 1.5 mm Hg; P=0.51) in children and −2.3 mm Hg (−4.5 to −0.04 mm Hg; P<0.05) in adults.

Conclusions An education programme delivered to primary school children as part of the usual curriculum is effective in lowering salt intake in children and their families. This offers a novel and important approach to reducing salt intake in a population in which most of the salt in the diet is added by consumers.

Trial registration ClinicalTrials.gov NCT01821144. 

Footnotes

  • We thank Peter Sever, Francesco Cappuccio, Kiang Liu, and Dong Zhao for their support and advice; the Changzhi Education Bureau, the headteachers and teachers of all participating schools, and children and their families who were involved in the research; all members of the field research team, particularly Yanbo Han, Peifen Duan, Zhifang Li, Jianbing Zhang, Cailing Wei, Yanli Zhai, Ruikai Zhu, Hui Yang, and Xiaoyun Wang; Yide Yang, Xiaorui Shang, and Wenyi Niu for their help with the development of the education materials; and Elizabeth L Turner and Xian Li for their helpful advice on the statistical analyses.

  • Trial Steering Committee: Peter Sever (chair), Francesco Cappuccio, Kiang Liu, Dong Zhao, Feng He, Yangfeng Wu, and Graham MacGregor.

  • Contributors: FJH, YW, CN, and GAM designed the study. FJH and YW contributed equally to the project. JM and HW designed the education materials. XXF, JZ, YM, and JY contributed to data collection and implementation of the education programme. FJH and YM developed the analysis plan, performed statistical analyses, and took responsibility for the integrity of the data and the accuracy of the data analysis. FJH wrote the manuscript. All authors contributed to the revision and approved the final manuscript. FJH is guarantor.

  • Funding: The study was funded by the UK Medical Research Council (MR/J015903/1). The study is part of the GACD (Global Alliance for Chronic Disease) Hypertension Programme. The funder of the study had no role in the design of the study; the collection, analysis, and interpretation of the data; the writing of the manuscript; and the decision to submit the article for publication.

  • Competing interests: All authors have completed the ICMJE uniform disclosure form at www.icmje.org/coi_disclosure.pdf (available on request from the corresponding author) and declare: FJH is a member of Consensus Action on Salt and Health (CASH) and World Action on Salt and Health (WASH). Both CASH and WASH are non-profit charitable organisations and FJH does not receive any financial support from CASH or WASH. GAM is chairman of Blood Pressure UK (BPUK), chairman of CASH, WASH, and Action on Sugar. BPUK, CASH, WASH, and Action on Sugar are non-profit charitable organisations. GAM does not receive any financial support from any of these organisations. CN is a member of WASH and AWASH (Australian division of World Action on Salt and Health) and does not receive any financial support from these organisations. CN has received remuneration from Meat and Livestock Australia, Nestle Health Science, and Dairy Health Consortium. These payments are unrelated to the submitted work. YM was sponsored by the China Scholarship Council while she was carrying out statistical analysis for this study at the Wolfson Institute of Preventive Medicine, Queen Mary University of London.

  • Ethical approval: The study protocol was approved by Queen Mary (University of London) research ethics committee (QMREC2012/81) and Peking University Health Science Centre IRB (IRB00001052-12072). Permissions were obtained from the local education authority (Changzhi Education Bureau) and headteachers of the schools. All participants who took part in the assessments gave written informed consent. For children, participant assent and parental written consent were obtained.

  • Transparency declaration: FJH affirms that the manuscript is an honest, accurate, and transparent account of the study being reported; that no important aspects of the study have been omitted; and that any discrepancies from the study as planned (and, if relevant, registered) have been explained.

  • Data sharing: No additional data available.

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