Mental health issues are increasingly prevalent among young adults in the Netherlands, with over half experiencing
psychological problems, which can have long-lasting consequences. Simultaneously, there is a global push towards more
sustainable, plant-based diets for environmental and health benefits. This project seeks to explore the intersection of these two critical issues, hypothesizing that a plant-based, high-fibre diet and other food compounds, such as pre, pro-, postbiotics, specific fats and vitamins, can improve mental health through the modulation of the gut-brain axis.
The Food4Mood project comprises a 20-week randomized controlled trial with about 180 young adults experiencing
mild mental complaints. The trial will consist of an 8-week personalized dietary intervention that includes citizen science
aspects, focusing on sustainably increasing plant-based dietary fibre intake. In the last 4 weeks of this intervention, an additional dietary supplement will be provided to the participants (e.g. pre, pro-, postbiotics, specific fats and vitamins) on top of the plant-based high fibre diet, to provide an extra trigger for the gut-brain axis. Measurements throughout the trial will assess mental health outcomes, gut microbiome composition, dietary behaviour towards plant-based foods and meals and other relevant health markers (e.g. sleep, physical activity, stool pattern, inflammation and wellbeing). The personalized dietary intervention approach in this project will provide scientific evidence supporting the shift towards a sustainable and healthy diet as strategy to enhance mental health, particularly among young adults. And the citizen science approach will add a novel dimension, empowering participants and enhancing the practical applicability of the findings. Alongside the trial, the project will include an extensive literature review and in silico analyses to develop predictive models for how diet influences mental health via the gut microbiome.
Success could reduce the long-term societal and economic burden associated with poor mental health, including
impaired social functioning and increased risk of chronic diseases. Insights from this study could inform public health
strategies, guide healthcare recommendations, and influence dietary guidelines, especially regarding the benefits of
transitioning to a more plant-based diet. Additionally, industrial partners will benefit from new knowledge about the effects of their products on the gut microbiome and mental health, potentially leading to innovation and growth. The project's outcomes will also contribute to future research on personalized nutrition and mental health, ultimately aspiring to contribute to a healthier, more resilient population with sustainable and healthy dietary habits.

The primary objective is to investigate the effects of a plant-based diet high in dietary fibres and an additional gut-brain axis trigger/support by dietary supplements/food products in the last 4 weeks of the intervention, on mental health outcomes and the role of the gut microbiota in this. As a secondary objective, this study will examine the effect of a personalized dietary intervention on long-term dietary behaviour change towards a more plant-based high fibre diet. Next to the dietary intervention trial, an extensive literature study will be conducted to obtain a better overview on the potential underlying mechanisms on how food can affect mental health via modulation of the gut-brain axis.

In the new ‘KIA Landbouw Water Voedsel’ there is an emphasis on sustainability, as the ambitions in the areas of health, safety and social and economic prosperity must fit within the limits of what the planet has to offer us and our children. Shifting towards a more plant-based diet has planetary as well as human health benefits. There is increasing evidence that plant based foods have a significantly smaller footprint on the environment than animal-based foods (WHO report Plant-based diets and their impact on health, sustainability and the environment; WHO-EURO-2021-4007-43766-61591-eng.pdf). A plant based diet is strongly linked to eating more dietary fibres, which are known for their positive direct and indirect effects on human health. Many health benefits of dietary fibres are currently attributed to their ability to odulate the gut microbiome. This can have substantial effects on gut health; however, via the gut-brain axis, it can also affect mental health. In addition to dietary fibres, there are other food compounds that can influence or trigger the gut-brain axis. One can think of pre-, pro-, and postbiotics, as well as specific fats and vitamins. Studying the health impact of the transition towards a more sustainable plant-based diet, and implementing strategies to stimulate a long-term eating behaviour change, accurately fits mission 4D of the KIA Landbouw Water Voedsel. Additionally, as a sustainable shift towards a more plant-based diet high in dietary fibre (incl. stimulating consumption of fruit and vegetables) attributes to the ‘Prevention’ theme that is addressed in the ‘KIA Gezondheid & Zorg’, our project would also fit into the Crossover with TKI Life Sciences and Health. Improvement of mental health in young adulthood can positively impact social functioning, relationships, career outcomes and physical health later in life, contributing to the aim of the Central mission of this KIA; 'living longer in good health’.

Understanding the relationship between diet, gut microbiota, and mental health is crucial not only for young adults
themselves but also for its societal implications in combating the rising prevalence of mental health problems among young adults. The findings of this study contribute to the development of lifestyle-based strategies aimed at improving the mental health of young adults. This is particularly important considering that early interventions can prevent the onset of major depression disorder and lessen the long-term consequences associated with poor mental health during young adulthood.
Additionally, this study will increase our understanding of the factors that drive long-term dietary behaviour changes. These findings will be relevant for public health organizations, healthcare professionals, universities, and, as a predominantly plant based diet recommended for sustainability (planetary health) reasons is being tested, for governmental organizations as well.
In addition, industrial partners can gain insight into the effects of their dietary supplements or (digital) tools on gut microbiota, mental health, and/or behavioural changes. For researchers, the findings will lead to shaping future research.