The blood type diet is a diet advocated by Peter D'Adamo and outlined in his book Eat Right 4 Your Type. Its basic premise is that ABO blood type is the most important factor in determining a healthy diet.

     The cornerstone of his theory is D’Adamo’s premise that lectins in foods react differently with each ABO blood type. Throughout his books he cites the works of various biochemists and glycobiologists as support for this theory. In his book, Eat Right 4 Your Type, “Lectins: The Diet Connection”, and in following chapters, lectins which interact with the different ABO type antigens are described as incompatible and harmful, ergo the selection of different foods for A, B, and O types to minimize reactions with these lectins.

     D'Adamo bases his ideas on the ABO classification of Karl Landsteiner and Jan Janský, and some of the many other tissue surface antigens and classification systems, in particular the Lewis antigen system for ABH secretor status. D'Adamo has gathered many references pertaining to blood groups on his website.

     The evolutionary theory of blood groups, which is also used by D'Adamo, stems from work by William C. Boyd, an immunochemist and blood type anthropologist who made a worldwide survey of the distribution of blood groups. In his book Genetics and the races of man: An introduction to modern physical anthropology, published in 1950, Boyd describes how by genetic analysis of blood groups, human races are populations that differ according to their alleles. On this basis, Boyd divided the world population into 13 geographically distinct races with different blood group gene profiles.

Source: diet2bhealthy.com