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

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.