TABLE 1.

Data extraction per field

Data fields	Extracted data
Study information	Authors, year, and study design
Intervention	Investigated dietary source and intervention setup
Patient characteristics	Sample size, age, disease duration, and Hoehn and Yahr stages
Levodopa characteristics	Type of levodopa treatment and daily dose
Outcome measures	Operationalization of levodopa-related outcome measures
Results	Statistical significance, quantified differences, and effect sizes
Risk of bias	Judgment made by Cochrane risk-of-bias tool