According to a systematic review of studies, blood type diets lack supporting evidence. View http://ajcn.nutrition.org/content/early/2013/05/22/ajcn.113.058693.abstract?papetoc
I have mentioned this many times to my patients that there is no perfect diet. Our complex constitution cannot be put in a box such as the blood type. In my book From Leaf to Life, I shared that the best diet is MODERATION in everything, including our opinions, our diet, our lifestyle etc.