Thanks for your input billbobby21.

When you say "Carbidopa also decreases the effectiveness of L-dopa as it depletes Vitamin B6 which is a co-factor in the conversion of L-dopa to Dopamine.", you seem to be focusing on the tree and ignoring the forest.

Carbidopa can not cross the blood brain barrier (BBB). Thus, carbidopa only inhibits the enzymatic action of AADC outside of the brain, which actually INCREASES the effectiveness of L-dopa, enabling much smaller doses of L-dopa to be used. When carbidopa is not used (e.g. Hinz protocol) much larger doses of L-dopa are needed, and these large doses of L-dopa can cause nausea (unless compensated for by the use of (large doses of?) 5-HTP (and other supplements?).

The main message I get from the research paper is that the effect of L-dopa on the serotonergic system (in different parts of the brain) is quite complex, and still not fully understood.

I also noticed that this research paper makes no reference to the research papers written by Hinz et al.

Jeff