Queen Mary University of London: New research shows that children can play an important role in lowering families’ salt intake

The controlled trial, conducted in northern, central and southern China where salt intake is high amongst both children and adults, included 54 primary schools with over 590 children (aged 8-9 years) and over 1180 adult family. During the study, children, parents and grandparents were taught about the dangers of eating too much salt and how to reduce it using a smartphone app, known as AppSalt. Salt reduction education, together with the routine health education curriculum, was integrated into the AppSalt system.

The app was installed on parents’ or grandparents’ smartphones. Children’s homework was to remind their parents and grandparents to complete the learning and tasks with them, following the step-by-step guide in the app. Salt intake was measured at the beginning and 12 months into the app-based education, each involving two consecutive 24-hour urine collections. School teachers organized the evaluation and facilitated the salt reduction education by communicating with children and their families through virtual chats or in-personal meetings.

The average baseline salt intake (i.e. before the salt reduction education) was 5.5 g/d for 8-9 years-old children, and 10.0 g/d for adults which is double the World Health Organization (WHO) recommended level. After one year of education, salt intake fell by 8% in adults which was accompanied by a fall of 1.6 mmHg in systolic blood pressure. In children, there were small falls in salt intake and blood pressure, but they were not significant.

Salt reduction is one of the most cost-effective public health measures as it lowers blood pressure, the leading cause of cardiovascular disease. Approximately 80% deaths from cardiovascular disease occur in developing countries. Whilst China is the largest developing country in the world, there were around 2.2 million stroke deaths and 1.9 million heart disease deaths in China during 2019. This continues to rise due to the rapid epidemiological and economic transitions.

Salt intake in China is very high and approximately 80% of the salt is added by the consumers during cooking or in sauces. So far, no country has demonstrated a successful salt reduction programme in such settings.

Professor Feng He, Professor of Global Health Research at Queen Mary University of London and lead author said: “This study provides a novel and feasible approach to reducing salt intake in the population where most of the salt in the diet is added by the consumers. Nationwide implementation could support salt reduction efforts, leading to a reduction in salt intake in the Chinese population and therefore a reduction in strokes and heart disease.”

Professor Graham MacGregor, Chairman of WASSH (World Action on Salt, Sugar and Health), Professor of Cardiovascular Medicine at Queen Mary University of London and co-author said: “This study has achieved a reduction in salt intake and blood pressure with the use of a smartphone app. Given the devastating impact salt has on health, all countries should adopt measures to reduce salt intake, including apps like AppSalt. In settings where most of the salt comes from processed foods, the industry also needs to reduce the huge and unnecessary amounts of salt they add to food. The best way of doing this is to set mandatory salt reduction targets, like in South Africa and Argentina.”

Mhairi Brown, Programme Lead of WASSH at Queen Mary University of London said: “Although this study was carried out in China, the methods could potentially be adapted by many other countries. Even in developed countries where most of the salt in the diet is from processed food, kids can still play a role in helping their family to reduce salt, for example by selecting food with less salt when shopping with their parents using a free app like FoodSwitch and getting them to reduce the amount of salt they add to their food.”

Professor Puhong Zhang, associate director at The George Institute for Global Health at Peking University Health Science Center and joint lead author said: “Primary school is a well-organised place where salt reduction education could be integrated into the existing health education curriculums and nearly all the families could receive the education through schoolchildren in a long run. This will help salt reduction across the whole population in China.”

Dr Yuan Li, Head of Nutrition and Lifestyle Program at The George Institute for Global Health at Peking University Health Science Center and co-author said: “The app-based education is well accepted by children, parents and teachers. With proper training and supervision, even individuals with minimal knowledge on the technology can learn to successfully use the app to acquire knowledge, set goals and monitor progress. Importantly, the app-based education could reduce workload for school teachers and ease the pressure on the already-busy school curriculum in China.”

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