Previous studies have suggested a link between fruit and vitamin C intake and an increased risk of Parkinson's. However, these studies have been primarily retrospective in design and are subject to recall bias. The current study is longitudinal, in which risk factor data was collected before onset of Parkinson's among more than 8,000 study subjects. Incidence of Parkinson's cases was noted over 34 years of observation.
Results of the study show that increased fruit and fruit drink consumption predicted an increased Parkinson's risk, after adjusting for other known risk factors. High dietary and supplemental intake of vitamin C did not appear to be associated with risk of Parkinson's.
"We speculate that this increased risk may be due to plant borne toxins, pesticides or herbicides, rather than the fruit itself," notes study author Andrew Grandinetti, PhD, of the Pacific Biomedical Research Center, University of Hawaii and Manoa. "High fruit intake is still an important protective factor against many chronic diseases. However, these findings suggest that further research into the role of food borne toxins may provide clarity as well as insight into the etiology and prevention of Parkinson's."