The Blood Type Diet Is Nonsense. Everyone Should Eat Plants!

The blood type diet is based on ABO blood typing

In 1996, a man named “Dr.” Peter J. D’Adamo pub­lished Eat Right For Your Type. This book pro­mot­ed the “blood type diet.” It claimed that your diet should be based on your ABO blood type (type A, B, AB, or O). The ABO sys­tem of blood typ­ing is impor­tant in blood trans­fu­sion. Get­ting a trans­fu­sion of the wrong type of blood can kill you. How­ev­er, there is no sci­en­tif­ic evi­dence that your blood type has any­thing to do with how your body reacts to food. Peo­ple of any blood type thrive on a low-fat, plant-based diet.

The things that D’Adamo says about the nat­ur­al his­to­ry of the dif­fer­ent blood types are wrong. So are the things he says about the effects of blood type on the body. Worst of all, D’Adamo gives par­tic­u­lar­ly bad dietary advice to the peo­ple with the most com­mon blood type. I sus­pect that his book has been so pop­u­lar because he has been telling a lot of peo­ple exact­ly what they want to hear. He has been telling the peo­ple with the most com­mon blood type that they need to eat a lot of fat­ty meat.

The Blood Type Diet theory

D’Adamo claims that type O was the orig­i­nal blood type of cave­men. Sup­pos­ed­ly, mod­ern-day peo­ple with type O blood should there­fore avoid eat­ing grains, espe­cial­ly wheat. Instead, they should sup­pos­ed­ly eat a meat-based diet. D’Adamo also claims that type A blood result­ed from the rise of agri­cul­ture. It sup­pos­ed­ly allows peo­ple to eat a high-car­bo­hy­drate diet. He argues that peo­ple with type A blood can there­fore eat a Mediter­ranean style diet based on grains and veg­eta­bles.

D’Adamo claims that type B arose in Asia, among Mon­go­lian herds­men. Thus, he argues that peo­ple with type B blood should eat a lot of cul­tured dairy prod­ucts. D’Adamo argues that peo­ple with type AB blood should eat a mixed diet. How­ev­er, he thinks that they should avoid eat­ing starch­es and pro­teins in the same meal.

D’Adamo also sells a broad range of prod­ucts. D’Adamo sells kits for test­ing your blood and sali­va. He sells a broad range of foods, teas, and dietary sup­ple­ments. He also sells skin care prod­ucts. Of course he does! The fact that he has such an exten­sive prod­uct line is a bad sign. Every sin­gle nutri­tion text­book I have ever read says that we should get our nutri­ents from food, not pills. Be wary of tak­ing any nutri­tion­al advice from some­one who sells sup­ple­ments!

But gorillas have type B blood!

Of course, D’Adamo is total­ly wrong about the his­to­ry of blood types. You can find types A and B in mon­keys and apes. All of the African and Asian pri­mates have some ver­sion of the ABO blood types. Mod­ern-day goril­las usu­al­ly have some­thing sim­i­lar to human type B. A few have some­thing like human type O, but none have human type A. Mod­ern-day baboons and orang­utans have a ver­sion of type A. Most chim­panzees also have a ver­sion of type A, but a few have some­thing sim­i­lar to human type O.  There is a lot of debate about this top­ic. How­ev­er, the con­sen­sus is that the ances­tral blood type was type A and that type B may have evolved sep­a­rate­ly sev­er­al times. The human AB blood type is just the result of some­one inher­it­ing the type A gene from one par­ent and the type B gene from the oth­er.

Why is type O so com­mon in mod­ern humans? Sci­en­tists are still not sure. One the­o­ry is that hav­ing type O blood makes you more like­ly to sur­vive a case of fal­ci­parum malar­ia, which is the worst form of malar­ia.

D’Adamo insists that peo­ple with type O blood should eat a meat-based Paleo-style diet. He insists that only peo­ple with type A blood should eat a veg­e­tar­i­an or veg­an diet. Yet there is no evi­dence that any­one would have bet­ter gen­er­al health on a Paleo-style diet. Extreme­ly low-carb (keto­genic) diets are some­times used as a treat­ment for severe epilep­sy in chil­dren. These diets work by mim­ic­k­ing the effect of fast­ing, but with­out caus­ing the per­son to starve.  How­ev­er, these low-carb diets are not good for the child’s gen­er­al health. In fact, they can stunt the child’s growth. The keto­genic diet can even cause severe side-effects, such as pan­cre­ati­tis.

ND stands for “not a doctor”

D’Adamo is often called “doc­tor.” But he is not a med­ical doc­tor (MD). Nor does he have a doc­tor of phi­los­o­phy (PhD) or a doc­tor of sci­ence (DSc) degree. Instead he has a doc­tor of natur­o­path­ic med­i­cine (ND) degree from Bastyr Uni­ver­si­ty. Bastyr is a school for peo­ple who want to go into an alter­na­tive health trade, such as natur­opa­thy or acupunc­ture. D’Adamo has taught at some oth­er schools, but they are just oth­er natur­opa­thy schools. In the ear­ly 20th cen­tu­ry, the schools of natur­opa­thy lost their abil­i­ty to grant MD degrees, because they refused to pro­vide a good enough sci­ence edu­ca­tion. Nev­er­the­less the natur­opaths have been fight­ing hard to get licen­sure to prac­tice as pri­ma­ry care providers. For infor­ma­tion about natur­opa­thy, see Natur­o­path­ic Diaries, the blog of ex-natur­opath Britt Marie Her­mes.

D’Adamo describes him­self as a researcher. How­ev­er, real researchers write arti­cles about their research. Those arti­cles then get pub­lished in sci­en­tif­ic and med­ical jour­nals. When I searched for P. J. D’Adamo in MEDLINE, I couldn’t find even one cita­tion. In oth­er words, D’Adamo has nev­er writ­ten even one arti­cle that any sci­en­tif­ic or med­ical jour­nal has seen fit to print. When I searched for his name in, I couldn’t find him list­ed as the main inves­ti­ga­tor of even one clin­i­cal study.

The real science of blood typing

The blood type diet is just an attempt to hijack the pres­tige of some real sci­en­tif­ic advance. The ABO blood typ­ing sys­tem was dis­cov­ered in 1900 by an Aus­tri­an immu­nol­o­gist named Karl Land­stein­er. Land­stein­er even­tu­al­ly won the Nobel Prize for this dis­cov­ery.

Your blood type is extreme­ly impor­tant if you need a blood trans­fu­sion. Even if you get blood that is well-matched to your own, you could suf­fer from fever and chills, as your immune sys­tem reacts to some unfa­mil­iar pro­teins from the donor. How­ev­er, if you get red blood cells of the wrong ABO blood type, your body may mis­take those red blood cells for a dan­ger­ous for­eign invad­er. As a result, your body’s anti­bod­ies could attack and kill those donat­ed red blood cells. In severe cas­es, the immune sys­tem will tear the for­eign red blood cells apart. This prob­lem, called an acute hemolyt­ic trans­fu­sion reac­tion, can kill you by caus­ing severe blood clot­ting.

The ABO sys­tem was the first set of blood types to be dis­cov­ered. Lat­er researchers revealed the Rh types (pos­i­tive and neg­a­tive). Peo­ple with AB-pos­i­tive blood (ABO type AB and Rh-pos­i­tive) can receive blood trans­fu­sions from prac­ti­cal­ly any­one. Peo­ple with O-neg­a­tive blood can donate to prac­ti­cal­ly any­one.

Blood typ­ing is also impor­tant in foren­sic med­i­cine. Before the days of DNA test­ing, it was often used to rule out sus­pects in cer­tain kinds of crimes. If you know that the per­pe­tra­tor had type A blood, you can rule out sus­pects with type O, B, or AB blood. In the days before DNA test­ing, blood typ­ing was impor­tant in pater­ni­ty cas­es. If a child has type A blood but his moth­er has type O blood, you know that the father must have had type A blood.

In oth­er words, blood typ­ing is extreme­ly impor­tant in trans­fu­sion med­i­cine and has been impor­tant in foren­sic med­i­cine. How­ev­er, there is no rea­son to believe that the dif­fer­ent blood types rep­re­sent dif­fer­ent stages in human evo­lu­tion. Nor is there any rea­son to believe that your blood type will let you pre­dict how you will react to a par­tic­u­lar diet. D’Adamo claims that a low-fat, veg­an diet should be reserved for peo­ple with type A blood. In real­i­ty, it’s the best diet for peo­ple with any blood type.

Pho­to by GreenFlames09

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