Quality assessment of "naturally occurring" high percentage L-dopa commercial products proposed as dietary supplements by Internet: from labelling to analytical findings

Federica Aureli¹Maria Cristina Gaudiano^1*Mariangela Raimondo¹Alessandro Maccelli¹Domenico Di Giorgio²Marta Gramazio²Anna Borioni¹Monica Bartolomei¹

• ¹National Institute of Health (ISS), Rome, Italy
• ²Italian Medicines Agency (AIFA), Rome, Lazio, Italy

Introduction L-dopa is a precursor of dopamine neurotransmitter and is used in Parkinson’s disease therapy. L-dopa dietary supplements are widely used as brain support. Among the L-dopa products claiming to contain botanical extracts, those from Mucuna pruriens are the most proposed on the Internet market. The natural percentage of L-dopa in Mucuna pruriens seeds or leaves varies from 1% to 7%, but extracts standardized at higher percentages of L-dopa are offered. Methods Four L-dopa products proposed as dietary supplements were purchased on the web and analysed for labelling. The identification of L-dopa and the search of undeclared pharmaceutical and nootropic ingredients was made by mass spectrometry (LC-MS Q-TOF). Nuclear Magnetic Resonance (NMR) spectroscopy was used to confirm the presence and to quantify of L-dopa. Furthermore, a study on the trend of interest for “levodopa” and “brain supplements” and the corresponding Italian terms was performed by Google Trends to investigate the interest for these topics in Italy and over the world in the last ten years. Results The visual inspection of labelling evidenced that the extract of Mucuna pruriens, which is not allowed in dietary supplements in Italy was stated in three samples, the extract of Vicia Faba was reported in one sample. Some labelling concerning the dosage of L-dopa were ambiguous. The LC-MS and NMR results evidenced the presence of L-dopa in all the samples. No other active pharmaceutical and nootropic ingredients were detected. The L-dopa amount in the capsules was found either as stated but also overdosed or under-dosed in the different samples. The trend analysis indicated an increasing interest for the term “levodopa” and “brain supplements” both in Italy and worldwide. Discussion The results obtained evidenced a risk related to the assumption of dietary supplements containing high dosage L-dopa purchased from Internet due to the presence of not allowed botanical extracts, to a not clear labelling and to dosages inconsistent with the labelled quantities. These findings, in light of the observed increase of interest in levodopa, highlight the need to control this market and to inform consumers and physicians of the risks associated with purchasing unauthorised products online.