Objective To determine whether a smartphone application based education programme can lower salt intake in schoolchildren and their families.
Design Parallel, cluster randomised controlled trial, with schools randomly assigned to either intervention or control group (1:1).
Setting 54 primary schools from three provinces in northern, central, and southern China, from 15 September 2018 to 27 December 2019.
Participants 592 children (308 (52.0%) boys; mean age 8.58 (standard deviation 0.41) years) in grade 3 of primary school (about 11 children per school) and 1184 adult family members (551 (46.5%) men; mean age 45.80 (12.87) years).
Intervention Children in the intervention group were taught, with support of the app, about salt reduction and assigned homework to encourage their families to participate in activities to reduce salt consumption.
Main outcome measures Primary outcome was the difference in salt intake change (measured by 24 hour urinary sodium excretion) at 12 month foll