My wife was diagnosed about 2 years ago. Her movement disorder specialist told us she encourages all of her PD patients to try probiotics because it seems like they can’t hurt and might help even though evidence is not super strong. She doesn't have any recommendations but found that a lot of her patients like Activia yogurt, which is pretty high in probiotics and also seems to help with constipation, especially if they make a breakfast parfait/sundae out of the Activia (particularly the prune flavor if you can find it!), bran flakes, and fresh berries. She told us that's been her recommendation to all of her PD patients so far. She also said it’s much easier to get the benefits when the probiotics are actually in whole foods rather than just in a supplement.