Inclusion criteria	Exclusion criteria
Population	Participants diagnosed with MCI using established criteria (e.g., Petersen criteria, NIA-AA, DSM-5)	Studies primarily include cognitively normal older adults, or dementia patients.
Intervention	Diet- and nutrition-related interventions, including: (1) whole foods/food products; (2) complete diets or dietary patterns; (3) enteral/parenteral nutrition formulas; (4) nutrient supplementation (single/multiple nutrients, bioactive compounds, plant-derived substances); (5) Multicomponent interventions (e.g., nutrition, nutritional education or counseling, combined with exercise or pharmacological treatments) also eligible.	Interventions limited to pharmaceuticals or herbal medicines.
Comparator	Any control condition (e.g., placebo, usual care, alternative intervention).
Outcomes	Any clinical, cognitive, or nutritional outcomes
Study design	Randomized controlled trials (self-identified as RCTs), including parallel RCT, crossover RCT and Factorial RCT	Secondary or post hoc analyses of RCTs; pilot/feasibility trials; duplicate reports from same trial (only main trial report included).

Box Inclusion and exclusion criteria.