Dietary Interventions for NCD Prevention in BRICS Countries: A Systematic Review with Emphasis on Nudge-Based RCT-Approaches

Background: Non-communicable diseases (NCDs) are rising rapidly in BRICS nations, yet evidence on context-specific dietary interventions, particularly nudge-based randomized controlled trials (RCTs), remains fragmented. This study synthesized RCT evidence on dietary interventions for adult populations in BRICS countries. Methods: A systematic review was conducted following PRISMA guidelines. PubMed, Scopus, and Web of Science were searched for RCTs (2015-2024) involving adults (≥18 years) in Brazil, Russia, India, China, and South Africa. Twenty-seven RCTs were included. Data on intervention type, outcomes, and risk of bias (Cochrane RoB 2) were narratively synthesized due to heterogeneity. Results: Of 27 RCTs, 41% were from China and 26% from India; 66% had high risk of bias. Interventions improved fruit and vegetable intake (+23.4 g/day; p=0.008), reduced systolic blood pressure (-10.0 mmHg; 95% CI -12.1, -7.9), and lowered HbA1c (-0.69%; 95% CI -0.99, -0.39; p<0.001). Digital interventions achieved significant reductions in BMI (-1.61 kg/m²; p<0.001) and energy intake (-331 kcal). Nudge-based strategies (15%) demonstrated reductions in sodium intake (-21%) and improved healthy food selection, but evidence was limited. Conclusion: Dietary interventions in BRICS countries improve diet quality and cardiometabolic outcomes; however, high risk of bias and scarcity of nudge-based trials limit definitive conclusions. Rigorous, age-specific RCTs are needed to strengthen NCD prevention strategies.