Motor fluctuations due to interaction between dietary protein and levodopa in Parkinson's disease.

Background: The modulation of levodopa transport across the blood brain barrier by large neutral amino acids is well documented. Protein limitation and protein redistribution diets may improve motor fluctuations in patients with Parkinson's disease but the pharmacokinetics and pharmacodynamics of levodopa and amino acids are highly variable.

Methods: Clinical records of 1037 Parkinson's disease patients were analyzed to determine the proportion of patients with motor fluctuations related to protein interaction with levodopa.