My brother had a bad breath problem for several years before being diagnosed with PD. He has always taken excellent care of his mouth, so it is not that...verified by his dentist. I'm just wondering if it could have been a gut flora problem, which I read recently might be linked to the death of dopamine producing neurons in the brain. Anybody else have this problem before being diagnosed? Could be big...or not.
Yes , liver is said to be the second brain and any malfunction in liver could lead to Parkinson's also .Liver's malfunction causes bad breath .
If you take and or eat to much zinc, selenium, or manganese it can cause bad breath and PD type symptoms from what I have read, especially manganese. I have been lowering copper levels and if I take to much zinc I have terrible breath and body odor that does not go away with showering. I also had that happen with selenium when I found out that I was hypothyroid and took to much selenium along with high selenium foods. Maybe do an HTMA and check for metals?
Yes I had bad breath too. Mouth wash didn’t help. It certainly could have been a “leaky”gut flora issue.
Many things can cause bad breath. Good luck with your search for his cause. There is also an odor or smell that PWP seem to just have exuding from their bodies. I'm somewhat surprised that I've not seen a post about this on here, but I've not been on this forum too long. Thankfully that is one of the symptoms which has reversed for my husband. 
I want to thank you all for your replies to my post back in February. My brother has now been diagnosed with stage 4 lung cancer that has spread to his liver. He has excellent health insurance and checkups so I don't know how this could go undetected for so long. It's crazy. This cancer must have been brewing in his body for years..? He is terminal, with 1-3 years left, but is trying IMMUNOTHERAPY (Keytruda), and he opted out of chemo, which kind of makes sense. Anyway, the first comment back in February was about the liver being the second brain, and that a liver malfunction could lead to Parkinsons. I am fairly sure he had the cancer before he was diagnosed with Parkinsons, so YES it appears that the liver is an important part of the entire Parkinsons dilemma. Thanks for your responses!
Parkinson's wife
Cause of Parkinson's as postulated by Noel Batten on blogtalkradio.com and Robert Rogers Ph.D
Carers suffer from Parkinson's too!
Reversal of Parkinson's versus Remission of Symptoms 
Parkinson's Right Side
