The invention is a diet-typing system for humans, including novel methods for diagnosis and treatment of food allergies and hypersensitivities. The diagnostic method correlates blood types (immunologically reactive antigens on RBC, skin and membranes) to four kinds of food allergies/hypersensitivities (IgE antibodies, IgG antibodies, T-cells, and Lectins). The results are used to identify and predict food allergies and hypersensitivities for six biological types (blood types A1, A2, B, O, A1B, and A2B), plus diet modifications for three subtypes (blood type Rh-negative, males and females). The treatment method uses the results to make food recommendations (to eat, limit, or avoid), based on the strength or classification of allergy scores, to mitigate the risk of food allergies and hypersensitivities in future persons. The diet-typing system presents the results on six diet cards, one for each blood type. The methods and resulting diets are unique, and differ substantially from prior inventions.