This would depend entirely upon Ken's perceptions of said blood. Given that it is his Heart, and, thus, his World, it is probably incredibly inadvisable to consume this blood, and there is a very high possibility it could potentially make your character incredibly ill and give them food poisoning.

As Rahti isn't human, she will likely survive drinking it the first time, but if she consumes enough of it, she will probably die. She would have to consume more of it than the others, however, to die; the rest of them would die much easier than she would.