Mucuna Pruriens, or Velvet Bean, is a bean that grows from vines in several places worldwide. It has a high L-Dopa content, among various other phytochemicals, and is generally taken as an extract according to L-Dopa dose. L-Dopa is a treatment for Parkinson's disease, and researchers seek to evaluate its effects compared with pharmaceutical L-Dopa and other drugs.
Concerning Parkinson's disease, the preliminary research we have suggests that, when the dose is matched, Mucuna Pruriens is roughly equivalent to pharmaceutical L-Dopa for reducing general symptoms, with a possibility of additional effects, but more research is needed to get an accurate sense of its efficacy.
The other main area of interest is sperm quality in infertile males. In this regard, preliminary evidence suggests it to be effective, with improvements in sperm motility and concentration being the best-substantiated effects. It is unclear how it affects fertile males, but the evidence so far suggests that it can notably improve the sperm quality of infertile males with a normal sperm count.
It carries the risk of the side-effects of L-Dopa, which include several gastrointestinal and neurological symptoms. In particular, Mucuna Pruriens has been found to increase nausea in a subset of participants in a trial, though other adverse events are unclear. Like other herbs, it always carries a risk of negative interactions with various medications.