Technology-supported interventions could help educate consumers on salt intake and manage blood pressure, according to observations from a one-year follow-up after a 12-month randomised controlled trial (RCT).
The RCT showed that an app-based education programme reduced salt intake and systolic blood pressure (SBP) in schoolchildren’s adult family members, and this study examined if the effects lasted at 24 months.
Researchers observed that the effect of the education programme on adults’ salt intake faded one year after the RCT. However, the SBP lowering effect and the improvement of salt-related Knowledge, Attitude, Practice (KAP) score remained, said researchers.
They added that continuous efforts are needed to maintain the salt reduction effects in real-world settings.
“In this 1-year follow-up after the cluster randomised clinical trial, the effect of the education program on adults’ salt intake faded, but the reduction of SBP and the improvement of KAP score remained 12 months after the RCT.
“There is potential for the lasting impact of the salt reduction intervention on blood pressure control. Efforts aimed at reinforcing a supportive environment, innovative technology, and viable strategy are needed to maintain lower salt intake in real-world settings,” wrote researchers in BMC Medicine.
“Moreover, the digital health especially the mobile health (mHealth) interventions demonstrate great potential in supporting behaviour change alongside the unprecedented coverage of intelligent mobile phones,” added researchers.
Managing salt intake and SBPThe global progress on salt reduction is barely satisfactory, partly due to the difficulty of changing people’s salt intake behaviour in particular for those countries where discretionary salt is widely used.
School-based intervention has shown to be a promising strategy to improve health outcomes both in children and their families, as the children and the parents are mutually affected in terms of health behaviour.
Researchers therefore developed an mHealth app-based education programme, AppSalt, for an RCT. AppSalt aimed to reduce salt intake in schoolchildren and their families in China.
There was a 97% retention rate of the AppSalt programme and an 80% completion rate of the whole app-based salt reduction courses, indicating the feasibility and acceptability of the interventions.
The results of AppSalt showed that the app-based education programme conducted through schoolchildren is effective in reducing the salt intake of their adult family members by 0.82 g/day after a 12-month intervention, along with a 1.64-mm Hg drop of systolic blood pressure. However, the long-term effect after the RCT is still unknown.
This study therefore aimed to evaluate whether the app-based intervention yielded sustained effects on the reduction of salt intake among children and their families at the end of the RCT.
The studyThis study (AppSalt) was designed upon a successful RCT (School-EduSalt), which encouraged children to deliver the salt-related knowledge and skills learned from schools to their families.
Guided by the same behaviour change theories including health belief model and social determinants of health, AppSalt integrated the traditional health education course and family salt intake monitoring task into a mobile app that could be installed in parents’ phones to facilitate the engagement of families.
For this parallel, cluster RCT, 54 primary schools from southern, central, and northern China were randomly assigned to either the intervention or control group. All participants – 594 children in grade 3 and 1,188 of their adult family members – were contacted again 12 months after the trial.
The primary outcome measured the difference in salt intake between the intervention and control groups at 24 months compared to baseline and 12 months, using the average of two consecutive 24-hour urinary sodium excretions.
The secondary outcome evaluated changes in blood pressure and salt-related KAP scores.
In adults, the salt reduction effect lessened over time, but the decrease in blood pressure was sustained at 24 months. No significant changes were seen in children’s salt intake or blood pressure, but both adults and children continued to show improved KAP scores, although the impact was smaller.
“The results showed that in adults, the salt reduction achieved over the intervention stage attenuated from 0.83 g/day to 0.38 g/day, while the SBP maintained about 2 mm Hg reduction effect at the 24-month follow-up. In children, there were no significant effects in reducing salt intake and blood pressure across the 24 months, whereas the improvement of KAP score persisted both in children and in adults with a mitigated effect size,” said researchers.
The sustained lower SBP found in this study showed the potential of the persistent effect of salt reduction intervention on the control of blood pressure, though further research is needed to explore the reason behind the persistence.
The relapse of the salt intake suggested that more effort is warranted to maintain a lower salt intake in the population after intensive interventions stop. The findings from this study supported the importance of a healthy food environment in facilitating healthier dietary choices of individuals. With digital health evolving rapidly, the innovative intervention strategy could provide stronger support for continuous behaviour change by integrating the behaviour change model with advanced techniques, concluded researchers.
The broader implications of these research findings lie in the integration of digital health tools into public health strategies. As high salt consumption remains a significant public health issue across Asia, especially in regions where discretionary salt use is common, interventions like these could help address this challenge.
By educating children to indirectly influence their family’s dietary behaviours, mobile health apps could play a key role in shaping long-term health habits. The continued use of such tools, backed by ongoing education and support, presents a promising opportunity for tackling salt intake and improving health outcomes across the region.
Source: BMC Medicine
DOI: https://doi.org/10.1186/s12916-025-03868-8
“Persistent effect of salt reduction in schoolchildren and their families: 1-year follow-up after an application-based cluster randomized controlled trial”
Authors: Li, Y., Zhang, P., He, F.J. et al.
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