I think its possible. Human body quikly adapts to new way of life. I wonder if A group is more prevailent among people who live or had ancestors who lived in areas where vegetable growing was important and B group people come from historicaly dairy regions (cheese, sirov burek, etc.) and so on.

Yeah, but it's very flawed. First blood type isn't O but it's A… it's A blood group that humans share with primates as monkeys and it's the oldest one…and secondly, never did people live only on agrarian, because agrarian products where at the time just an addition to the overall diet… i don't believe anywhere did Europeans stopped eating meat just because they had wheat and stuff :/

imo it's a fail, thought i'm still interested in what others think…and for example then Italians would be heavilly blood type A if it was truth since during Roman times they were heavily on agrarian diet… while English, Scandianvians and most Slavs and such would heavily be blood type O since they used to hunt more and eat meat rather than seed and crop, but the reallity is bloodtype A is a very common group in Scandinavia for example. Most of Europeans belong to O and A bloodtype  ::)

Well i am not scientist so i dont know these things. I just say it is possible. As i understand this diet it dosent exclude meat for A blood type but just says that they should eat more vegetables and less meat. So basicaly each group is encouraged to eat more of "their" own food and less other kind of food.

If this diet theory is realistic then i must dissagree with you about Slavs. As i understand it Slavs were grain producers. Ancient Slavs developed heavy plough. Bread is highly esteemed in our culture and also look at Slavic menu, we have in common kasha's and other porridges. Buckwheat is practicaly slavic holy grain etc. I agree that they also hunted but thats becouse Slavic lands are so wast so there is lots of wild game.

I personaly believe Slavs had balanced and diverse diet but grains were main element in ancient Slavic cuisine.