I never take any notice of vampires, they suck *groan*

On another note, the blood type diet (which I've read) is almost a paradigm of pseudo-science. It makes all kinds of claims about human evolution which are totally spurious and made up of whole cloth. Don't believe it.

Ditto. One of the most mysterious diet books I’ve ever read. Seems only D'Adamo's father & son found it scientific. To me, honestly speaking, it has nothing in common either with science or with paleolithic nutrition. Well, I do accept there is some correlation between blood type and risk of various diseases, but why making a mountain out of a molehill and declare each blood type requires its own diet:?
Contrary to D’Adamo’s mystic assumptions, there has been the phylogenetic analysis revealing that human A and B allels are at least a few million yrs old. Blood types A and B are as just paleolithic as an O.

Didn’t want to get into debates, but since you mentioned

I have to agree, the blood type diet is complete garbage.
But, as P.T. Barnum didn't actually say, but is credited with saying, "There's a sucker born every minute."

Kay

Blood type doesn't matter. We're all humans and all have the same digestive tracts, anatomical parts, give or take a few missing muscles or minor brain structure differences. Among the healthy humans, we're all the same genetically and species-wise, because we can all mate with each other.

I got into the blood-type mantra for the first month before I really got into low carb, high fat eating, and ditched it as I became more educated about low carb. I don't think blood type has anything to do with your dietary needs as humans. We're all biologically the same and require the same nutrients to survive.