Considerations for developing a targeted amino acid supplement for people with Parkinson's disease that promotes health while accounting for pathophysiology and medication interference.

For individuals with Parkinson's disease (PD), dietary habits affect disease symptoms, progression, and overall health. Protein consumption is of great interest because of the direct and indirect effects of specific amino acids (AAs) on disease progression and interference with levodopa medication. Proteins comprise 20 distinct AAs with varying effects on overall health, disease progression, and medication interference. Therefore, it is important to consider both the potential beneficial and detrimental effects of each AA when considering supplementation for an individual with PD. Such consideration is of particular importance because PD pathophysiology, altered dietary patterns associated with PD, and competitive absorption with levodopa have been shown to result in characteristically altered AA profiles (eg, some AAs are stored in excess while others are deficient). To address this problem, considerations for the development of a precision nutritional supplement that targets AAs specific to the needs of people with PD are discussed. The objective of this review is to provide a theoretical framework for such a supplement, detailing the current state of knowledge relating relevant evidence to such a supplement, and highlighting areas of future research. Specifically, the general need for such a supplement is discussed before a systematic examination is provided of the potential benefits and risks of dietary supplementation of each AA in people with PD. As a part of this discussion, evidence-based recommendations are provided regarding the inclusion or exclusion of each AA for such a supplement for people with PD, and areas are highlighted where additional research is needed.