Considering that there are some prodromal symptoms in PD at the intestinal level, such as alteration in the composition of the intestinal microbiota and deposition of alpha-synuclein, at some point before the disease develops, and that the degree of nutritional status may influence the severity of motor symptoms of the disease, additional studies should be conducted on fecal microbiota to better understand how to improve the gut-brain relationship, as well as nutritional studies and how nutrition in these patients can modify the microbiota, thus acting on their QoL. This evidence concerns the gene SNCA and Parkinson disease.