Knowing Your Beans in Parkinson's Disease: A Critical Assessment of Current Knowledge about Different Beans and Their Compounds in the Treatment of Parkinson's Disease and in Animal Models

Abstract, Parkinsons Disease, 2019

This review contains a critical appraisal of current knowledge about the use of beans in both animal models and patients with Parkinson's disease (PD). The potential beneficial effects of beans in PD are increasingly being touted, not only in scientific journals but also by the lay media. While there is a long tradition in Ayurvedic medicine of prescribing extracts from Mucuna pruriens (MP), whose seeds contain 5% L-3,4-dihydroxyphenylalanin (L-DOPA), many other beans also contain L-DOPA (broad beans, common beans, and soybeans) or have other ingredients (coffee and cocoa) that may benefit PD patients. Indeed, bean-derived compounds can elicit neuroprotective effects in animal models of PD, while several studies in human PD patients have shown that motor performance can improve after ingestion of bean extracts. However, there are several arguments countering the view that beans serve as a natural therapy for PD: (i) the results from animal PD models are not necessarily directly applicable to humans; (ii) beans have many bioactive ingredients, some of which can be harmful in large doses; (iii) studies in human PD patients are scarce and only report on the effects of single doses or the administration of bean extract over short periods of time; and (iv) no data on long-term efficacy or side effects of bean therapy are available. Therefore, reservations about the use of beans as a “natural” therapy for PD seem to be justified.

Ed. emphasis :  "Mucuna seeds are rich in protein and in their processed form serve as a food supplement in several regions in Africa and Asia [19]. Raw seeds are not considered safe for human consumption due to the high amount of toxic alkaloids such as L-DOPA, as well as the hallucinogen dimethyltryptamine [20]. The concentration of these components can only be reduced by roasting, drying, or cooking, whereby the cooking water needs to be discarded repeatedly [3, 19]. Accordingly, during the 1989 civil war in Mozambique, mass psychosis was reported in a remote area in which the inhabitants were forced to nourish themselves with Mucuna beans, but had insufficient amounts of water to boil them in [20]. Their nonnutritious contents also limit the use of untreated Mucuna seeds as animal feed, except for ruminating mammals, who can adapt to L-DOPA via a microbial-driven fermentation process [3]."