Pycnogenol
Pycnogenol is extracted from French Maritime Pine Bark. While I take/test many supplements I would never want to be out of Vitamin D3 with Vitamin K2 MK7 but in a bind for a short period of time if I could only have one supplement it would be my Pycnogenol.
There is cheap pine bark on the web but I like Pycnogenol extract because it has solid research behind it.
Below www.greenmedinfo.com has a list of 118 scientific studies abstracts using Pycnogenol. I am not a member but there is enough info in the abstracts to find more details with Google.