Administration of levodopa for Parkinson’s disease (PD) has remained the most effective therapy for symptom management despite being in use for over 50 years.

Advancing disease and age, changing tolerability, and gastrointestinal (GI) dysfunction may result in changes in dietary habits and body weight, as well as unpredictable motor fluctuations and dyskinesias. Dietary proteins that convert into amino acids after digestion are implicated as major factors that inhibit levodopa absorption. For people living with PD (PwP) who experience motor fluctuations, low protein diets (LPD) and protein redistribution diets (PRD) may be effective and are often recommended as a non-pharmacologic approach for improving levodopa bioavailability. However, there is a lack of consensus on a standard definition of these diets and appropriate treatment algorithms for usage. This may be due to the paucity of high-level evidence of LPD and PRD in PwP and whether all or specific subgroups of patients would benefit from these strategies. Proper education and monitoring of diet and protein intake may reduce complications associated with these diets, such as dyskinesias and unintentional weight loss. Additionally, alterations to medications and GI function may alter levodopa pharmacokinetics. In this narrative review, we focus on 1) mechanisms of dietary protein and levodopa absorption in the intestine and blood-brain barrier, 2) dietetic approaches to manage protein and levodopa interactions, and 3) practical issues for treating PwP as well as future directions to be considered.