Parkinson’s Dietary Study

Matthew Phillips Talk on Parkinson’s Dietary Study

Is there an “optimal” diet for Parkinson’s?

This question has been debated for years. On one hand, low-fat, high-carbohydrate diets may increase brain dopamine, an important chemical deficient in Parkinson’s. On the other hand, a high-fat, low-carbohydrate “ketogenic” diet may enhance the brain mitochondria that produce energy for brain cells. 

In 2017, 47 volunteers with Parkinson’s joined investigators from Waikato Hospital led by neurologist Matthew Phillips to conduct a randomized controlled pilot trial comparing the effects of a low-fat versus a ketogenic diet on the motor and nonmotor symptoms of Parkinson’s. 

The results of the study, “Low-fat versus ketogenic diet in Parkinson’s disease: A pilot randomized controlled trial”, were published online in Movement Disorders in August (freely available at 

During the 8-week study, half of the participants engaged in a low-fat diet, half in a ketogenic diet. The groups were well matched regarding age, Parkinson’s symptoms, sex and other variables. Throughout the study, the participants were assessed by the same neurologist on the same weekday at the same time of day. The neurologist who conducted the assessments was blinded to the randomisation.

Total calories of the diets were kept the same. The amount of protein consumed by each group was also kept the same.

After 8 weeks, the ketogenic group experienced a 41% improvement in nonmotor symptoms, compared to only 11% improvement in the group that consumed the low-fat diet. 

The nonmotor symptoms that improved the most in the ketogenic group were generally those that respond least favourably to levodopa – urinary problems, pain, fatigue, daytime sleepiness, and cognitive impairment.

“These exciting results have made their mark, for they suggest that a change in diet – in this case, a ketogenic diet – may improve some of the most disabling, least levodopa-responsive symptoms of Parkinson’s,” Phillips said.

Two limitations of the study are the low number of participants and the short duration, so the findings should be considered preliminary. Phillips said the findings suggest that a ketogenic diet may be a good complement to levodopa therapy for Parkinson’s, pending the results of longer, randomised trials.


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