Whether there is actual blood in the ingredients has never been revealed, however, the Star Trek Cookbook suggests that bloodwine is made of fermented blood and sugar.
Fermented blood, I just assumed.
Seems there's no word on it for sure.
Drinking blood is no worse than eating flesh.
So long as the donor is non sapient.
You heard of Black Pudding?
https://en.wikipedia.org/wiki/Black_pudding