"Here's some information about tyrosine and probiotics in relation to Parkinson's disease:

Tyrosine
A small study found that people with Parkinson's who took 45 mg of L-tyrosine per pound of body weight for three years had better clinical results than those who took L-dopa. Another study found that 1,000 mg of L-tyrosine daily was safe and well tolerated for people with Parkinson's who were also taking dopamine therapy and other anti-Parkinson's medications.

Probiotics
Research suggests that probiotics may help with constipation, an early indicator of Parkinson's disease. Some research also suggests that the probiotic Bacillus subtilis can protect against the build-up of a protein that causes motor symptoms in Parkinson's. However, there isn't enough research to recommend probiotics as a treatment for other Parkinson's symptoms.

Gut bacteria and tyrosine
Gut bacteria can impact the availability of therapeutic drugs, including levodopa, the primary treatment for Parkinson's. Bacterial tyrosine decarboxylases (TDC) can decrease levodopa levels by converting them to dopamine. Bifidobacteria can metabolize tyrosine, which can lead to a higher dosage requirement for levodopa. "

https://www.nature.com/articles/s41598-023-4595...).