Food-drug interactions knowledge and clinical competence among registered dietitians

BACKGROUND: Food-drug interactions (FDIs) are increasingly prevalent due to chronic disease and polypharmacy and may compromise therapeutic efficacy and patient safety. Registered dietitians play a critical role in identifying and preventing FDIs through dietary assessment and counselling in clinical practice; however, their knowledge and competence in this domain remain poorly characterised. METHODS: A cross-sectional observational study was conducted using a structured self-administered online questionnaire among 151 registered dietitians, active members of the Portuguese Order of Nutritionists (Ordem dos Nutricionistas), in 2024. Knowledge of general and clinically relevant FDIs, prior education and training exposure, perceived adequacy of FDI knowledge, and self-reported training needs were assessed. Descriptive and comparative analyses examined knowledge patterns by professional experience and area of practice. RESULTS: Participants demonstrated a good understanding of basic FDI concepts. However, specific knowledge of clinically relevant interactions averaged 58.72% (Sufficient), with markedly lower accuracy for interactions involving propranolol (22.5%) and warfarin (42.4-62.3%). Although most respondents (93.4%) reported prior academic exposure to FDIs, only 23.2% considered their knowledge sufficient for practice. Furthermore, 21.2% had undertaken complementary training beyond their bachelor's degree, suggesting a felt need to supplement formal education. Greater knowledge was observed among registered dietitians working in clinical practice and those with more professional experience. CONCLUSIONS: Registered dietitians demonstrated foundational awareness of FDIs, but also important gaps in clinically relevant interaction knowledge and perceived competence. These findings highlight the need to strengthen FDI content in nutrition curricula and continuing professional development to support safe and effective practice in populations exposed to polypharmacy.