Effects of vitamin B12, folate, and entacapone on homocysteine levels in levodopa-treated Parkinson's disease patients: A randomized controlled study

Introduction: Previous studies have suggested a significant increase in plasma homocysteine (Hcy) levels in levodopa-treated Parkinson's disease (PD) patients, and vitamin B12 and folate supplementation may decrease Hcy levels. However, the effects of catechol-O-methyltransferase inhibitors on levodopa-induced increase in Hcy levels were conflicting. The aim of this study was to evaluate whether Hcy levels are increased in levodopa-treated PD patients and to evaluate the effects of vitamin B12 and folate or entacapone on Hcy levels in levodopa-treated PD patients. Methods: We analyzed and compared plasma Hcy levels in 20 levodopa-naive PD patients and 42 levodopa-treated PD patients, followed by randomized assignment of 42 levodopa-treated patients to treatment groups with either vitamin B12 and folate, entacapone, or no medication. Results: Plasma Hcy levels in levodopa-treated PD patients were higher than those in the control group, but the difference was not statistical significant (15.25 +/- 6.70 and 13.13 +/- 4.68, P = 0.216). Patients treated with vitamin B12 and folate had a significant decrease in plasma Hcy levels (P < 0.001). In the entacapone group, Hcy levels were mildly decreased, but the change did not reach statistical significance. Conclusion: Levodopa-treated PD patients had higher plasma Hcy than levodopa-naive PD patients. Unlike entacapone, combination supplementation with vitamin B12 and folate was associated with sig-nificantly decreased plasma Hcy. We suggest that plasma Hcy levels should be monitored during levo-dopa treatment, and supplementation with inexpensive vitamin B12 and folate is beneficial for levodopa-treated patients. (c) 2021 Elsevier Ltd. All rights reserved.