From www.*******.com:

27th April 2011 - New research

INTESTINAL BACTERIA IS HIGHLY PREVALENT IN PARKINSON'S DISEASE

Movement Disorders [2011] 26 (5) : 889-892 (Gabrielli M, Bonazzi P, Scarpellini E, Bendia E, Lauritano EC, Fasano A, Ceravolo MG, Capecci M, Rita Bentivoglio A, Provinciali L, Tonali PA, Gasbarrini A.) Complete abstract

Small intestinal bacterial overgrowth has been found to be highly prevalent in Parkinson's Disease. Parkinson's Disease is associated with gastrointestinal motility abnormalities that could favour the occurrence of small intestinal bacterial overgrowth. The aim of this study was to assess the prevalence of small intestinal bacterial overgrowth in people with Parkinson's Disease. The prevalence of small intestinal bacterial overgrowth was far higher in people with Parkinson's Disease. It occurred in over half (54%) of all people with Parkinson's Disease, in contrast to only 8% of people that do not have Parkinson's Disease. The severity of Parkinson's Disease was also very significantly related to small intestinal bacterial overgrowth.

This can lead to the following symptoms : excess gas, abdominal bloating and distension, abdominal pain, and diarrhea or in some cases chronic constipation. For more information go to Small intestinal bacterial overgrowth. The researchers suggest that the gastrointestinal motility abnormalities that often occur in Parkinson's Disease might explain this association. In order to refer to this article on its own click here.

If your sinemet doesn't seem to work as well, could be your small intestine (where it is absorbed) is laden with bacteria that are interfering. Someone here posted an article that h. pylori colony size actually increases with sinemet, kind of like a tape worm grows bigger when you eat. Sick analogy, I know, sorry.

Edit: not sure why it won't let me list the website but it's *******.
Yep, it deleted it again. Anyone knows, let me know.