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Table 1 Improvements in non-motor symptoms found in studies of ketogenic diet in Parkinson’s disease

From: Nutritional Ketosis in Parkinson’s Disease — a Review of Remaining Questions and Insights

Study lead author/year published Ketogenic diet (KD) design Primary outcome Results Comments
Van Itallie, 2005 [14] Open-label, single-arm 7 participants KD × 4 weeks Pilot feasibility in the home; UPDRS performed weekly Decreases in total UPDRS by approximately 20–40% Strict ketogenic diet goal, 90% lipids by energy, only 5 participants (after 2 dropouts)
Phillips, 2018 [15] Open-label, randomized 47 participants to KD vs. low-fat diet (LFD) × 8 weeks Within and between group mean differences in total MDS-UPDRS scores baseline to 8 weeks Improvements in MDS-UPDRS I scores (KD within-group − 4.58 ± 2.17). Between-group subjective improvements in urinary frequency, pain, daytime sleepiness, cognitive impairment improvements vs. low-fat diet. No between-group differences for MDS-UPDRS II, III, or IV Mean BOHB 1.19 mM (attained therapeutic target)
2 dropouts in KD group due to perceived side effects (worsening tremor and/or rigidity)
Krikorian, 2019 [13] Open-label, randomized 18 participants to KD vs. low-fat diet (LFD) × 8 weeks Proof of concept effects of NK on cognitive performance in a PD-MCI cohort
Outcomes included: MDS-UPDRS-III, finger tapping test, Controlled Oral Word Association Test, verbal paired associate learning test, California Verbal Learning Test
Improvements in lexical access and working memory in KD group compared to LFD group; no between-group differences in MDS-UPDRS-III or finger tapping Exploratory analysis (no primary outcome or power analysis specified)
Low mean ketosis in KD group (0.31 mM at week 8)
Non-standardized protein, higher intake in low-carb group (123 g vs. 89 g mean daily protein)
3 dropouts in KD group (1 for perceived side effect)
  1. UPDRS Unified Parkinson’s Disease Rating Scale, MDS-UPDRS Movement Disorder Society Unified Parkinson’s Disease Rating Scale, BOHB beta-hydroxybutyrate, MCI mild cognitive impairment