Parkinson's disease (PD) is a complex neurological disease that affects ~6.1 million people worldwide - mostly older adults >60 years. The most effective treatment for PD is dopaminergic therapy, particularly levodopa (Ldopa). People with PD have variable responses to Ldopa, including degrees of motor fluctuations (MF) throughout the day. The half-life of Ldopa is ~1.5 h and therefore, dosage and timing are essential to mitigate MF. Ldopa is a large neutral amino acid (LNAA), and the bioavailability of Ldopa is compromised when simultaneously ingested with LNAA (e.g., leucine). Both Ldopa and LNAAs from food are absorbed through the same intestinal transporter, but LNAAs from food are preferentially absorbed by the enterocyte, limiting the bioavailability of Ldopa. Thus, the scientific community often recommends the protein-redistribution diet (PRD). With PRD, patients limit protein (<10 g) at the desired time of medication efficacy (daytime) and meet their protein needs during the evening meal (~70+g). There are deleterious implications of the PRD for older adults with PD; consumption of >30 g of protein, in a single meal, will not sufficiently increase muscle protein synthesis. Additionally, the impact of the PRD on skeletal muscle quality and function has not been determined, and it is unclear, based on prior studies, whether the PRD enhanced drug absorption. Therefore, the objective of this study is to address these gaps in knowledge. This study will quantify the effects of dietary protein pattern on skeletal muscle in PD; determine the effects of dietary protein pattern on sleep quality in PD. This study is an acute, 5-week, crossover intervention with PD participants randomly assigned to first adhere to either the PCD or PRD. Participants will receive diet prescriptions and meal plans for their respective diet, and outcome measures will be assessed at days 0, 14, 21, and 35.
The purpose of this pilot study is to generate preliminary data on the impact of the dietary protein pattern on markers of skeletal muscle health and drug efficacy in Parkinson disease.