Steve, dopamine can not cross the blood-brain barrier.

To quote:

"Namely, L-DOPA, but not dopamine, is transported across the BBB in humans via the L1 facilitative transporter (Hawkins et al., 2006). [My emphasis]"

Source; http://www.sciencedirect.com/science...96627308000342 .

That means that eating dopamine-rich foods (I am not sure what you mean by this) is completely pointless as far as increasing the levels of dopamine in the brains of people with PD or any other people for that matter is concerned.

On the other hand, L-DOPA can be transported across the BBB and is then converted into dopamine in the brain - I tried to explain this to you above.

That is why L-DOPA is indicated for people who live with PD.

I hope that this clears things up for you - it is all basic biomedical science.