Nutrition is a major modifiable determinant of health. National nutrition surveys are essential tools to monitor the population nutritional status and guide nutrition policies. Switzerland conducted its first national survey, menuCH, in 2014-2015. A total of 2 086 Swiss residents aged 18 to 75 years old were interviewed and their diet assessed using two 24-hour dietary recalls. This thesis aimed at 1) describing dietary intake of Swiss adult population using menuCH data, and 2) developing recommendations for the next national nutrition surveys and future nutrition policies.
menuCH data indicated that the vast majority of the Swiss adult population poorly adhered to the national dietary guidelines. The population consumed insufficient plant-based products, and excessive ultra-processed and/or animal-based foods. Moreover, food consumption patterns substantially differed between the German, French and Italian-speaking parts of Switzerland. Finally, we showed that regularly consuming a breakfast rich in fruit, unsweetened cereal flakes, nuts and yogurt was associated with reduced abdominal obesity.
Since menuCH did not survey children nor collect bio-samples, we tested child-specific dietary assessment methods and evaluated acceptability of bio-sample collection in a feasibility study to prepare the next national nutrition survey. We recruited a population-based sample of 53 children aged 3 to 17 years in Lausanne. The developed dietary assessment tools (e.g., 24-hour food diary, food questionnaire) were well accepted by participants and their caregiver(s). Compliance with the collection of spot urine, venous and capillary blood, and toenails was high in the different age groups.
As shown above, dietary behaviours in Switzerland are not optimal. Classically, public health can propose two types of interventions to improve the situation: 1) provide information to encourage behavioural modifications (individual level), or 2) change the environment to reduce exposition (population level). I wrote an essay about a novel instrument designed to improve diet, i.e., precision nutrition. I concluded that providing personalized advice at a large scale via smartphones (individual level) might have a limited effect on dietary behaviours and obesity, if environments promoting unhealthy food are not modified in parallel (population level).
We have shown that Switzerland needs public health interventions to improve dietary behaviours. We suggest that these interventions target in priority the food environments to facilitate access to healthy foods. Furthermore, the next national nutrition surveys should include children, strengthen dietary assessment methods, and collect bio-samples for relying on objective nutritional biomarkers. We believe that this will improve the assessment of dietary intake and nutritional status at both individual and population levels to further fine-tune national dietary guidelines and guide future nutrition policies.