Literature Review

Does adherence to a Mediterranean diet reduce the risk of Parkinson’s disease?



Among older adults, adherence to a Mediterranean diet is associated with lower probability of prodromal Parkinson’s disease, according to research published in Movement Disorders.

Ingredients for a Mediterranean diet snyferok/Thinkstock

“Recommending the Mediterranean diet pattern, either to reduce the risk or lessen the effects ... of prodromal Parkinson’s disease, needs to be considered and further explored,” said lead author Maria I. Maraki, PhD, of the department of nutrition and dietetics at Harokopio University in Athens, Greece, and her research colleagues.

Evidence regarding the effect of a Mediterranean diet on Parkinson’s disease risk remains limited, however, and physicians should be cautious in interpreting the data, researchers noted in accompanying editorials.

“There is a puzzling constellation of information and data that cannot be reconciled with a simple model accounting for the role of diet, vascular risk factors, and the neurodegenerative process and mechanisms underlying Parkinson’s disease,” Connie Marras, MD, PhD, and Jose A. Obeso, MD, PhD, said in an editorial. Given Maraki et al.’s findings, “most of us would be glad to accept that such a causal inverse association exists and can therefore be strongly recommended to our patients,” but “further work is needed before definitive conclusions can be reached,” Dr. Marras and Dr. Obeso wrote. Dr. Marras is affiliated with the University Health Network and the University of Toronto. Dr. Obeso is affiliated with University Hospital HM Puerta del Sur, CEU San Pablo University, Móstoles, Spain.

The role of diet

Prior research has suggested that adherence to the Mediterranean diet – characterized by consumption of nonrefined cereals, fruits, vegetables, legumes, potatoes, fish, and olive oil – may be associated with reduced risk of Parkinson’s disease. In addition, studies have found that adherence to the Mediterranean diet may be protective in other diseases, including dementia and cardiovascular disease. Dr. Maraki and her colleagues sought to assess whether adherence to the Mediterranean diet is associated with the likelihood of prodromal Parkinson’s disease or its manifestations. To calculate the probability of prodromal Parkinson’s disease, the investigators used a tool created by the International Parkinson and Movement Disorder Society (MDS) that takes into account baseline risk factors as well as prodromal markers such as constipation and motor slowing.

They analyzed data from 1,731 participants in the population-based Hellenic Longitudinal Investigation of Aging and Diet (HELIAD) cohort in Greece. Participants, 41% of whom were male, were aged 65 years or older and did not have Parkinson’s disease. They completed a detailed food frequency questionnaire, and the researchers calculated how closely each participant’s diet adhered to the Mediterranean diet. Diet adherence scores ranged from 0 to 55, with higher scores indicating greater adherence.

The median probability of prodromal Parkinson’s disease was 1.9% (range, 0.2%-96.7%), and the probability was lower among those with greater adherence to the Mediterranean diet. This difference was “driven mostly by nonmotor markers of prodromal Parkinson’s disease,” including depression, constipation, urinary dysfunction, and daytime somnolence, the researchers said. “Each unit increase in Mediterranean diet score was associated with a 2% decreased probability for prodromal Parkinson’s disease.” Compared with participants in the lowest quartile of Mediterranean diet adherence, those in the highest quartile had an approximately 21% lower probability for prodromal Parkinson’s disease.

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