Here's a single-case study involving Fisetin (found in strawberries, apples, and onions) that improved symptoms:
"The basic diet alone failed to prevent decline due to PD. In 2009, the basic diet was enhanced with a good dietary source of both fisetin and hexacosanol. Six months after the patient started the enhanced diet rich in fisetin and hexacosanol, a clinically significant improvement in symptoms was noted; the patient's attending neurologist reported that the clinical presentation of cogwheel rigidity, micrographia, bradykinesia, dystonia, constricted arm swing with gait, hypomimia, and retropulsion appeared to be resolved. "
Someone posted details not in the abstract:
" The patient’s medication dosage in December 2008, before
beginning the complete diet rich in fisetin and hexacosanol,
included 7½ carbidopa/levodopa 25/100 and 1mg
of rasagiline daily. By June 2009, 6 months after starting the
complete diet rich in fisetin and hexacosanol, the patient was
able to reduce the medication dose to 4½ carbidopa/levodopa
25/100 and ½ mg of rasagiline daily, while benefiting
from amelioration of motor symptoms. In October 2011
medication doses were 6 carbidopa/levodopa 25/100 CR and
¼mg of rasagiline, while maintaining the significant improvement
in allCUSS motor movements obtained in 2009.
Then I found where the patient herself posted an update this year:
" I'm the retired dietitian in the article. (My neighbors wanted me to share how my walking, etc, improved so dramatically, thus the published article.) Here's an update. I was doing well until late 2013 when I developed an allergy (characterized by flushing and breathlessness) to strawberries and several other foods. By February 2014 I had to stop consuming strawberries. Many of my symptoms began to worsen. In June 2014 I started taking the Swanson brand of fisetin. To approximate the amount in strawberries I divide the each capsule into six portions, taking one at breakfast and one a dinner. Over several months my symptoms again improved.
" In January 2015 I became intolerant of rasagiline and synthroid, stopping both in February 2015. Without the rasagiline, I have more tremor, etc, but am able to function well. I'm currently taking 6 carbidopa/levodopa 25/100, and one 25/100 CR at 10 PM.