Both low fat and ketogenic diets appear to be safe and may be salutary in patients with Parkinson disease (PD), according to researchers affiliated with the Department of Neurology at Waikato Hospital in Hamilton, New Zealand.1 Both diets significantly improved motor and nonmotor symptoms, with the ketogenic diet having greater improvements in the latter.
The research team noted preliminary evidence suggests that diet manipulation may influence motor and nonmotor symptoms in PD, but the ideal fat-to-carbohydrate ratio has yet to be fleshed out. A low-fat, high-carbohydrate diet may ease tyrosine uptake and/or trigger an insulin-induced increase in dopamine. On the other hand, a high-fat, low-carbohydrate “ketogenic” diet may induce chemical reactions that enhance mitochondrial oxidative phosphorylation and central and peripheral neuron energy metabolism.
The study engaged 47 patients with PD and a Montreal Cognitive Assessment score of >20, aged 40 to 75 years, to an 8-week diet intervention in which patients were randomized to either a low-fat (n=23) or ketogenic diet (n=24). To follow the given diet, patients were supplied with weekly shopping lists, daily menus, suggested recipes, and forms to record of blood glucose and ketone levels.
Patients also were instructed to take their medication (levodopa) at least 1 hour before or after any meal. Metabolic parameters and International Parkinson and Movement Disorder Society (MDS-UPDRS) scores were assessed at baseline and at regular intervals during the study.
At the study end, 20 (87%) patients in the low-fat diet group and 18 (75%) in the ketogenic group were completers. MDS-UPDRS Parts 1 to 3 scores significantly decreased in both groups, with a more substantive decrease for Parts 1 (nonmotor daily living) and 2 (motor daily living) in the ketogenic group. (P < .001 vs P = .030 and P =.011, respectively).
Patients in the ketogenic group scored better than patient in the low-fat group (per changes in MDS-UPDRS scores) regarding urinary problems, pain, fatigue, daytime sleepiness, and cognitive impairment. Whereas a decrease in Part 4 MDS-UPDRS scores (motor complications) were seen in the ketogenic diet group, no change was seen in the low-fat group.
1. Phillips M, Murtagh D, Gilbertson L, et al. Low-Fat Versus Ketogenic Diet in Parkinson’s Disease: A Pilot Randomized Controlled Trial [abstract]. Mov Disord. 2018;33 (suppl 2). http://www.mdsabstracts.org/abstract/low-fat-versus-ketogenic-diet-in-parkinsons-disease-a-pilot-randomized-controlled-trial. Accessed October 10, 2018.