Introduction and Research Approach
In the current era, there is a prevailing trend of improper dietary intake and a growing trend of social media usage. Given this growth in social media usage, the concern about misinformation, mainly health-related misinformation, is increasing. Social media plays an essential role in the prevalence and impact of health-related misinformation. More specifically, the concern of nutritional supplement misinformation and its effect on adolescents and young adults is growing and under-researched. Adolescents and young adults have unknown preferences, and current policies fail to address the problems associated with nutritional supplement misinformation. Understanding the specific preferences of adolescents and young adults and the socio-technical system is crucial to address the issue. Therefore, as the Dutch context has not been researched, this research explicitly addresses the problem of nutritional supplement misinformation among Dutch adolescents and young adults and aims to improve public health outcomes. This thesis aims to develop interventions and design requirements within the system of nutritional supplements, social media, and public health outcomes to maximize public health. The research deploys the Value-Sensitive Design (VSD) framework to address the issue.

Results
To fully address the socio-technical system, structured literature reviews were conducted to assess the influences in the system and investigate the institutional environment. The comprehensive, structured analysis of the literature and the assessment of the institutional environment pointed out the complex nature of the system and its associated stakeholders, where social media algorithms also play a significant role. Interviews and a focus group identified the values, risks, value tensions, and possible interventions at stake in the system. This extensive value analysis identified the main values to design for. In designing, the value of public health is paramount.

Based on the identified values to design, constructing value hierarchies led to the design requirements. By including the stakeholder values, the interventions are theoretically sound. The most promising interventions identified in this thesis are certificating influencers, counter campaigns, educational campaigns, and an automated enforcement tool. This research sees all four interventions as suitable interventions to implement, where the extension to the certification of influencers and the counter campaigns are most suitable to deploy first. The research mainly showed the need for prevention interventions to boost awareness and consumer education concerning health and social media.

Contributions
This research has shown that VSD can aid design in addressing a societal and policy issue, where VSD originally stems from technology design (Friedman et al., 2006). In addition, this thesis provides grounded interventions to offer novel perspectives in addressing nutritional supplement misinformation. Furthermore, the policies implied by the study are within the context of the Netherlands but could also be considered internationally. This thesis can also fuel the broader problem of health misinformation and other problems with nutritional supplements, as well as the discussion of the responsibility of social media platforms and other industrial stakeholders within the identified socio-technical system.

Global mental healthcare confronts daunting challenges, notably posttraumatic stress disorder (PTSD), necessitating immediate attention and innovative solutions. Many individuals requiring mental health support face various barriers, including social stigma, low perceived need, and restricted access to care providers — especially prevalent in certain regions — which impedes their quest for professional assistance. Amidst these obstacles, artificial intelligence (AI) emerges as a promising instrument, ushering in its unique challenges and opportunities. This thesis delves into these intricacies, aiming to develop comprehensive and pioneering design guidelines for AI applications within mental healthcare. The research focuses on three pivotal areas: identifying the distinct challenges and opportunities of implementing AI in mental healthcare; adapting existing AI design principles to fit the mental health landscape; and understanding the crucial role of multidisciplinary collaboration and user-centered design in this context. The primary objective is to devise guidelines that address inherent difficulties in mental healthcare, such as stigma and complexity of disorders, while leveraging potential benefits like early support intervention and expanded access to mental healthcare services. The suggested design guidelines embrace a systematic approach, encapsulating problem definition, stakeholder engagement, data acquisition, ethical and legal considerations, model design, system deployment, usage, maintenance, and iterative improvements based on feedback. Grounding these guidelines in a practical context, the thesis introduces AnchorAid, a tool that is designed theoretically and remains hypothetical. This virtual assistant provides post-trauma recovery support by gathering data, generating personalized feedback, recommending symptom management strategies, and assisting clinicians in the patient management processes. Through design guidelines establishment and their implementation via AnchorAid, this thesis lays a solid foundation for AI integration into mental healthcare.