I take 15% L-dopa mucuna as well, and I don't have a good reason to do so other than that tendency many of us have to try to increase dopamine, perhaps because of the natural tendency to want to "feel good" and the association of dopamine with the reward pathways in the brain.
Most L-dopa is converted to dopamine outside the brain if it isn't taken with a dopamine decarboxylase inhibitor such as carbidopa. The peripheral dopamine isn't what we're looking for; we're trying to boost it in the brain, not the rest of the body.
Mucuna has been used for generations without any signs of toxicity. There have been no such cases. At all.
L-dopa on the other hand, has been shown to be neurotoxic in studies.
From what I've read, the many other compounds in mucuna do have, as you suggest, modifying effects on the potential toxicity of l-dopa. Foolishly, many companies are selling mucuna extract that is standardized to as much as 99% l-dopa, which would probably be more neurotoxic and contain fewer of the other benefits of mucuna. I think even the 15% extract is probably a bit high. 5% extract is available and it's what I would choose if I were to buy it again, which I won't.
With green tea I can only literally take a pinch of it and it has much stronger marked stimulatory effects. Because green tea contains a compound that allows l-dopa to cross the BBB easier it seems to enhance the effects considerably.
It's known that COMT (another aid in making l-dopa effective) effects obtain from green tea, but I've never seen a study confirming the decarboxylase activity of any natural substance. What I have seen are people commenting that green tea extract (and catechins in general) have this property, but I've not seen a reference to any study other than one that was conducted in rats, and that study has been discounted by others and never replicated. Still a possibility, though. I'm intrigued by the major impact that green tea has on your personal experience! Would be interesting to know if it's COMT related or if it's really a decarb. inhibitor. I take a lot of catechins, not just green tea extract but also A
cacia catechu (so named for the high concentration of catechins) and yet I still don't detect much difference with the mucuna. This might be due to my being on too many other supplements plus a couple psych meds. It's hard for me to detect the individual effects of most of the things I take.
Edited by deeptrance, 27 April 2012 - 05:17 PM.