Levodopa Content of Mucuna pruriens Supplements in the NIH Dietary Supplement Label Database

Botanical supplements may contain pharmaceutically active drugs that affect the presentation, natural history, and management of disease. One example is Mucuna pruriens, a bean containing levodopa, which has been investigated as a potential treatment for Parkinson disease.¹ The prevalence of M pruriens supplement use in the US is unknown, but a recent survey of 205 patients with Parkinson disease found that 7% of supplement users used M pruriens supplements to treat the disease.²

The Office of Dietary Supplements at the National Institutes of Health (NIH) maintains an online database of dietary supplement labels.³ This case series study was designed to measure the levodopa content of M pruriens supplements in the NIH’s database and compare the quantity of levodopa in the supplements with the quantity of levodopa in extracts of authenticated M pruriens seeds.

In November 2021, supplements with “Mucuna pruriens” on the label in the NIH Dietary Supplement Label Database were identified. The 20 brands most recently added to the database in 2021 were purchased online. Products were excluded from this case series if the actual label did not contain both “dietary supplement” and “Mucuna pruriens.” Two authenticated samples of M pruriens seeds were obtained from the National Center for Natural Products Research repository at the University of Mississippi.

Ground seeds and powder from dietary supplement products were reconstituted in water. All samples were analyzed for the presence and quantity of levodopa using ultra high-performance liquid chromatography. For products that listed a specific amount of M pruriens seed extract per serving on the label, estimated quantity of levodopa was calculated by multiplying the declared quantity of M pruriens seed extract by the highest percentage of levodopa found in the extracts of authentic M pruriens seeds. Products were also screened for the presence of carbidopa and benserazide. eMethods 1 to 6 in the Supplement include additional details.

Of the 20 supplement products identified in the database, 1 was unavailable for purchase, 1 was a duplicate entry, and 2 did not contain both “Mucuna pruriens” and “dietary supplement” on the actual label; therefore, 16 products were analyzed. One product did not contain detectable levels of levodopa. In the remaining 15 products, the quantity of levodopa ranged from 2 mg to 241 mg per recommended serving size (Table). Extracts from authenticated M pruriens seeds were found to contain 2.5% to 3.9% levodopa. In supplement products that listed a specific quantity of M pruriens seed extract on the label, the actual quantity of levodopa was 228% to 2186% greater than the estimated quantity. Carbidopa and benserazide were not detected.

Levodopa doses from 2 mg to 241 mg in M pruriens supplements were unpredictable based on the declared quantity of M pruriens seed extract on the label. One previous investigation of 6 M pruriens supplements sold in the US also found a wide range of levodopa (from 4 mg to 354 mg per serving).⁴ It is not possible to directly compare the pharmacologic effects of levodopa in M pruriens supplements with prescription levodopa, typically formulated in 50-, 100-, 200-, and 250-mg doses, in part because prescription levodopa includes a peripheral decarboxylase inhibitor not present in M pruriens supplements.

This study has several limitations. Only 2 authenticated samples of M pruriens seed extracts were analyzed, and it is possible that different variants of M pruriens or different extraction methods might affect the quantity of levodopa.⁵ In addition, only 1 sample of each brand of supplement was analyzed, and it remains unknown if the dose of levodopa varies from batch to batch over time. Given these findings, clinicians may identify unsuspected levodopa consumption by asking patients about the use of supplements and advising that consumption of M pruriens supplements may unpredictably complicate the management of Parkinson and other diseases.

Accepted for Publication: June 6, 2022.

Published Online: August 8, 2022. doi:10.1001/jamaneurol.2022.2184

Corresponding Author: Pieter A. Cohen, MD, Department of Medicine, Cambridge Health Alliance, 1493 Cambridge St, Cambridge, MA 02139 (pcohen@challiance.org).

Author Contributions: Drs Cohen and Avula had full access to all of the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis.

Concept and design: Cohen, Khan.

Acquisition, analysis, or interpretation of data: Cohen, Avula, Katragunta.

Drafting of the manuscript: Cohen.

Critical revision of the manuscript for important intellectual content: All authors.

Statistical analysis: Avula, Katragunta.

Administrative, technical, or material support: Khan.

Supervision: Cohen.

Conflict of Interest Disclosures: Dr Cohen reported receiving grants from The Pew Charitable Trusts and Consumers Union and being the subject of a civil suit brought by Hi-Tech Pharmaceuticals, a supplement company (the jury found in Dr Cohen’s favor), both outside the submitted work. No other disclosures were reported.

Additional Contributions: The authors thank Patricia Redd, MLS, of Cambridge Health Alliance for her expert assistance in obtaining obscure references and Céline Vanhee, PhD, of the Department of Medicines and Health Products, Sciensano, Belgium, for her thoughtful comments on an earlier version of the manuscript. They were not compensated for their contributions.