Multiple Micronutrient Supplementation With Digital Layering Among Adolescents in Tanzania

Adolescence (10-19 years) is a critical period of rapid growth and development, second only to the first 1,000 days of life. In low- and middle-income countries, including Tanzania, adolescents experience a double burden of malnutrition, with anemia and other micronutrient deficiencies co-existing alongside rising rates of overweight and obesity. Iron deficiency and poor dietary diversity are major drivers of anemia and are associated with impaired cognitive function, reduced physical capacity, poorer school performance, and compromised future reproductive health. Adolescent girls are at particularly high risk because of increased iron requirements related to growth and menstruation, often in the context of poverty, food insecurity, and constrained access to health services.

At the same time, access to mobile phones and digital technologies is expanding in sub-Saharan Africa, though important inequities remain by geography, gender, and socioeconomic status. Digital health and nutrition strategies (e.g., SMS reminders, mobile messaging, social media content) have shown promise in improving knowledge, some health behaviors, and adherence to supplementation. However, most evidence comes from high-income settings, and few interventions have been designed for or rigorously evaluated among adolescents in low-resource African contexts. Existing programs often emphasize information provision rather than sustained behavior change and rarely address structural barriers to digital access or gender-related inequities. There is limited evidence on how to design and implement digital strategies that effectively complement micronutrient supplementation for adolescents in sub-Saharan Africa.

This trial builds on work by the Africa Research, Implementation Science and Education (ARISE) Network and the ARISE-NUTRINT initiative, which have documented high levels of adolescent anemia and malnutrition in sub-Saharan Africa and explored how adolescents engage with digital technologies for health. Prior mixed-methods research in Tanzania has shown that adolescents are interested in digital nutrition content but face barriers such as limited or shared device access, school policies restricting phone use, and the cost and quality of internet connectivity. The present study is designed to test whether "digitally layered" nutrition education strategies, added to a standard package of multiple micronutrient supplementation (MMS), can reduce anemia and improve nutrition-related behaviors among adolescents.

The ClinicalTrials.gov registration pertains to the main randomized controlled trial. The intervention package was informed by preceding co-design and prototyping phases involving adolescents and key stakeholders (parents, teachers, school administrators, government representatives, civil society, software engineers, and content developers). Using a human-centered design approach, these preparatory phases identified adolescents' needs, preferences, and barriers related to nutrition, anemia, and digital access, and were used to develop and refine prototypes of SMS/WhatsApp messages, in-person digital sessions, and youth-created digital content. Only the finalized intervention components emerging from these phases are evaluated in the main trial.

The main study is a three-arm, individually randomized, non-blinded controlled trial conducted within the Dar es Salaam Health and Demographic Surveillance System (HDSS) area in Tanzania. A total of 1,200 adolescents (approximately equal numbers of boys and girls) aged 15-19 years with access to at least one mobile phone (own or shared) will be enrolled. Participants are randomized in a 1:1:1 ratio, stratified by gender, to: (1) Control; (2) Intervention Arm I (digital Strategy I); or (3) Intervention Arm II (digital Strategy I plus digital Strategy II). Each participant is followed for approximately 9 months, with data collection at baseline, midline (4 months), and endline (9 months).