Effects of three nutritional approaches on metabolic health and Parkinson’s disease: A 32-week crossover study

Background: Parkinson’s disease (PD) is a neurodegenerative disorder with motor and non-motor symptoms that impair quality of life. Altered neuronal glucose metabolism may contribute to PD symptoms, suggesting a potential role for nutritional interventions. Aim: To examine three dietary approaches in relation to PD symptoms, sleep, fatigue, cognition, and metabolic biomarkers. Setting: This 32-week, fully virtual crossover study recruited participants across the United States. Interventions, assessments, and monitoring were completed remotely. Methods: Sixteen participants completed three 8-week dietary phases separated by 4-week washouts. Glucose and ketones were monitored during Phases II and III. Laboratory measures were obtained at baseline and after each phase. Standardised PD scales, exit surveys, adherence and interviews assessed outcomes and participant experiences. Results: Body weight and glycated haemoglobin improved significantly during the low-carbohydrate ketogenic diet plus medium-chain triglyceride (MCT) oil phase. Changes in PD-specific scale scores were not statistically significant. Participants qualitatively reported improvements in energy, cognitive clarity, sleep, and selected PD symptoms. Conclusion: A low-carbohydrate ketogenic diet with MCT oil may improve metabolic outcomes and selected patient-perceived symptoms in PD. Adherence and gastrointestinal intolerance may affect long-term feasibility. Contribution: This study provides preliminary evidence on nutritional interventions, metabolic health, and PD-related symptoms. It also demonstrates the feasibility of remote nutritional research using telehealth, home monitoring, and standardised PD scales. Larger controlled trials are needed to determine whether metabolic improvements translate into clinically meaningful PD outcomes.