The effect of dietary protein on the efficacy of L-dopa: a double-blind study.

Author(s): Tsui JK, Ross S, Poulin K, Douglas J, Postnikoff D, Calne S, Woodward W, Calne DB

Affiliation(s): Department of Medicine, University Hospital, University of British Columbia, Vancouver, Canada.

Publication date & source: 1989-04, Neurology., 39(4):549-52.

Publication type: Clinical Trial; Randomized Controlled Trial

We randomly placed 10 parkinsonian patients on high- and low-protein diets that tasted and looked alike, each for 1 week. All patients were taking L-dopa and carbidopa with or without other antiparkinson medications; medications remained unchanged. A "blind" physician recorded the modified Columbia scores, objective measurements of rigidity, movement velocity, and pegboard tests three times a day for 5 days during each week. The patients recorded fluctuations hour to hour. We measured serial blood L-dopa levels on day 4 of each week. Performance was significantly better while the patients were on low-protein diets. These results did not correlate with blood L-dopa levels, which had higher peaks in three patients while they were on high-protein diets despite inferior performance and increased number of "off" hours. Thus, high dietary protein probably affects the efficacy of L-dopa at a central level.