Yes, always discuss with your GP before taking any natural preparations, as Island Mike says.
Before going on Madopar, I did a six month experiment with natural Levadopa, (Mucuna Pruriens), with the approval of my doctor. I kept a diary of dosage and how I felt each day. Whilst I got some benefit, it wasn't enough to improve my symptoms dramatically. My neurologist suggested that I should go on Madopar and I ended my experiment. He also said that there was natural Levadopa in broad beans, which is the same family as MP. So, although they're not my favourite vegetable, I eat broad beans regularly! (I buy the frozen ones from Morrison's).
I think we owe it to ourselves to keep an open mind about using alternative natural methods of dealing with our symptoms, as long as we talk it through responsibly with our medical experts. After all, WE know our own body better than anyone else and until a cure comes along, I don't think anyone should be chastised for trying to help themselves.