The massive amounts of L-Dopa that America consumes, comes from the chemical "stating material", Vanillin, by a short classic reaction sequence involving "asymmetric hydrogenation". It is the Vanillin that is obtained by steam distillation of Vanilla pods, grown in the tropics, that is the "commodity" that controls L-Dopa production and supply. If there was ever a shortage problem, there are other semi-synthetic routes to L-Dopa that would be put into immediate use, using guiacol or other intermediates to make the ton quantities of our "gold standard" drug. Dopa supply should be stable for as long as their are people like us who need it to live. cs