Effects of a Nutritionally Balanced Between-Meal Food Product on Brain Function in Older Adults: Protocol for a Randomized Controlled Trial (the MiniMeal Study)

BACKGROUND: Increasing evidence suggests that diet influences gut microbiota composition and systemic inflammation, which in turn may affect brain health, cognitive function, and mood regulation. Elevated levels of systemic inflammation have been associated with reduced resting-state functional connectivity within the default mode network, a pattern linked to poorer cognitive performance in older adults. Dietary interventions incorporating anti-inflammatory foods, such as oat bran and chickpeas, may help attenuate low-grade inflammation and promote healthier dietary behaviors in aging populations. OBJECTIVE: This study protocol describes a randomized controlled trial designed to investigate the effect of healthy between-meal products on brain activity in older adults. METHODS: The MiniMeal study is a 9-week, 3-arm randomized controlled trial comprising a blinded, 2-arm intervention and a nonblinded, no-intervention comparison group. A total of 114 community-dwelling men and women aged ≥70 years (38 per group) will be randomized to 1 of 3 study arms. Participants in the intervention group will consume the MiniMeal products, while those in the reference or control group will receive reference or control products. In both intervention arms, products will be consumed twice daily, either replacing or supplementing habitual morning, afternoon, or evening between-meal occasions. All other dietary habits will remain unchanged. Participants in the no-intervention group will maintain their habitual diet throughout the study period. The primary outcome is functional brain activity, assessed using functional magnetic resonance imaging during the n-back task, comparing the intervention and reference groups. Secondary outcomes include comparisons with the no-intervention group and assessment of other neural measures, biomarkers in blood, body composition, physical function, and self-reported well-being. RESULTS: Ethics approval was obtained from the Swedish Ethical Review Authority (Etikprövningsmyndigheten) on February 20, 2024. Participant recruitment was completed on December 18, 2025. Data collection was completed by February 27, 2026. Data analysis is ongoing since January 7, 2026. A total of 114 participants were enrolled, of whom, 106 completed all 6 study visits. CONCLUSIONS: This study will provide insights into whether nutritious between-meal products influence brain function in older adults and will explore potential underlying biological mechanisms. The findings are expected to contribute to a better understanding of the relationship between dietary habits and cognitive health in older adults and may inform future research on diet-based strategies to support in healthy aging. TRIAL REGISTRATION: ClinicalTrials.gov NCT06353984; https://clinicaltrials.gov/study/NCT06353984. INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): DERR1-10.2196/94648.