The Influence of Levodopa and the COMT Inhibitor on Serum Vitamin B12 and Folate Levels in Parkinson’s Disease Patients

Serum folate and vitamin B12 levels were measured in 67 consecutive Parkinson’s disease patients treated either with levodopa + dopa decarboxylase inhibitor (DDC-i) plus catechol-O-methyltransferase inhibitors (COMT-i) or only with levodopa + DDC-i. The data were compared to 67 age-matched controls. Our findings show that levodopa-treated Parkinson’s disease patients have low folate (p < 0.0007) and vitamin B12 levels (p < 0.0003). They also demonstrate that the addition of a COMT-i to levodopa + DDC-i treatment causes lower serum vitamin B12 (p < 0.03) and folate levels (p < 0.005) than levodopa + DDC-i treatment alone. We suggest supplementary treatment with vitamin B12 and folic acid in these situations.