Influence of Dietary Constituents on Motor and Non-motor Symptoms in Parkinson’s Disease

Abstract

Despite intensive research during the last decades, the actual trigger for the degeneration of dopaminergic and other neurotransmitter systems in Parkinson’s disease (PD) still remains to be identified. Numerous epidemiological studies have suggested that nutrition may play an important role in the pathogenesis of PD and influence the risk to develop the disease, which is supported by recent research in animal models indicating that ascending alpha-synuclein pathology in the central nervous system may originate from the enteric nervous system. In contrast, there have been only very few clinical studies investigating whether symptoms of PD can also be ameliorated by nutritional components after the onset of disease. Physicians will consequently find it hard to make dietary recommendations to their PD patients, which are not purely based on beliefs rather than on scientific evidence. This chapter aims to summarize the limited data from clinical trials investigating the effects of dietary constituents on motor and non-motor symptoms of PD. After promising results in cell cultures and animal models of PD, food components such as antioxidants, methylxanthines, polyphenols, unsaturated fatty acids, and vitamins have been repeatedly suggested to have symptomatic or even disease-modifying effects in PD. However, scientific evidence from clinical trials for a beneficial influence of these nutritional components in PD is still limited and often inconclusive, which in some studies may have been the consequence of inadequate sample sizes and treatment lengths and hence lack of statistical power to detect potentially mild effects of dietary factors on disease outcomes. Instead of aiming to investigate symptomatic effects of single dietary components, future studies should also consider to examine combinations of constituents with different mechanisms of action since this approach may be more fruitful in a disease with multiple underlying pathomechanisms and relatively slow progression. Given the low cost and good tolerability of dietary components, investigations of the interplay between nutrition and PD remain a very interesting topic and should be pursued further in the future.