Title: Ketogenic Diet and Motor Outcomes in Parkinson’s Disease: A Meta-analysis of Randomized Trials
Authors: Ana Leticia Fornari Caprara, Jamir Pitton Rissardo, Jorge Patino, Andrew McGarry, Ian Walker
Conference: 2026 International Congress of Parkinson's Disease, Seoul, Korea
Objective
To evaluate the effects of ketogenic diet (KD) interventions on motor outcomes and adverse events in Parkinson’s disease (PD).
Background
Metabolic therapies such as KD have been proposed to improve mitochondrial efficiency and reduce oxidative stress in PD, potentially improving motor symptoms; however, existing trials report variable results and lack consensus on clinical impact and safety.
Design/Methods
A meta-analysis of PubMed-indexed randomized controlled trials evaluating KD in PD was performed. Extracted data included MDS-UPDRS-III and MDS-UPDRS-II in the ON state, weight, metabolic biomarkers, and adverse event risks. Effect sizes were calculated as mean differences (MD) or relative risks (RR) using inverse-variance and Mantel-Haenszel methods, applying random-effects models when appropriate.
Results
Five trials involving 129 participants were analyzed. KD did not significantly improve MDS-UPDRS-III (MD 0.97, 95% CI −1.99 to 3.92) [Figure 1] or MDS-UPDRS-II (MD −1.45, 95% CI −3.12 to 0.23) [Figure 2]. No consistent effects were observed for weight (MD 0.19, 95% CI −1.34 to 1.72) [Figure 3], glucose (MD 0.54, 95% CI −0.02 to 1.10), or triglycerides (MD 0.15, 95% CI −0.24 to 0.55). A significant reduction in A1c (MD −0.33, 95% CI −0.61 to −0.05) and an increase in total cholesterol (MD 1.57, 95% CI 1.19 to 1.95) were observed. Adverse event rates were comparable between KD and control groups, with nonsignificant relative risks for constipation (RR 3.80, 95% CI 0.18–80.57), fatigue (RR 0.73, 95% CI 0.10–5.22), and dizziness (RR 0.88, 95% CI 0.14–5.60).
Conclusions
KD did not produce significant improvements in motor function. Metabolic effects were minimal, and adverse events were comparable to controls. Larger, longer-duration studies are needed to clarify the therapeutic role of KD in PD.
Citation
Caprara AL, Rissardo JP, Patino J, McGarry A, Walker I. Ketogenic Diet and Motor Outcomes in Parkinson’s Disease: A Meta-analysis of Randomized Trials. Mov Disord 2026;41(Suppl_1): S1211-S1213.
Figure 1. Forest plot of pooled MD of motor outcomes.
Figure 2. Forest plot of pooled MD of UPDRS-II.
Figure 3. Forest plot of pooled MD of weight change.