There are only
meager facts which show some
vague, at best, connections between body functions relating to
digestion and
blood types.
1. The level of LDL, (the "bad" cholesterol), can increase in response to a low fat diet. The degree of this adverse effect depends on one's blood type.
2. There is a certain intestinal enzyme going under the ugly name "high molecular mass intestinal alkaline phosphatase". During fasting, this enzyme works best for blood groups O and B and the lowest activities were associated with blood group A.
3. Depending on one's blood type, there can be higher or lower probability of duodenal ulcer. However, this relations can be masked by food habits, diet, smoking, and family history.
4. Certain types of sugars in the blood are blood-type dependent: the "blood group A trisaccharide" and "blood-group-active oligosaccharides", all having different reactions to oral intake of galactose (a free sugar), lactose, and sucrose.
5. The concentrations of so called gut-brain regulatory peptide gastrin during fasting and after meals were different depending on blood type.
this information was taken from dietandbody.com