Help Serrapeptase aka Serratiopeptidase

What evidence is there that serrapeptase/serratiopeptidase crosses the blood-brain barrier other than this rat study that looked at the effects of serrapeptase and nattokinase in treating Alzheimer's disease?


I have searched most English websites, but have not been able to find much evidence. Maybe there is a website in Japanese with more information? After all, it was originally discovered in Japan and is used in Japan as a drug more commonly than here in the US.

You can try searching onセラペプターゼ (serrapeptase) and 血液脳関門 (blood-brain barrier)