Blood Type Diet: Does It Work?

Chapter summary

Peter D’Adamo’s book Eat Right 4 Your Type claims your ABO blood type is the main factor in a healthy diet.
His mechanism is lectins: proteins in food that he says react differently with each blood type.
There is no scientific data to support the diet or the lectin theory. Some data contradicts it.
Blood type is inherited, and 33 blood group systems are recognised. ABO and RhD are the main two.

Type O (“hunter”): more meat and fish. Limit starches and avoid wheat, grains, beans, legumes and dairy.
Type A (“cultivator”): vegetables, fruit, grains, beans, limited fish. Avoid meat, wheat and dairy. Close to vegetarian.
Type B (“nomad”): lamb, mutton, rabbit and most meats, plus dairy. Avoid chicken.
Type AB (“enigma”): many meats, seafood, dairy, beans, grains and fruit, but limit kidney beans, lima beans, seeds, corn, beef, chicken and buckwheat.

Dietitians, doctors and most scientists: No provable science shows blood type determines the best diet. D’Adamo also got some anthropology wrong.
Supporters: Many followers say they feel better and lose weight.
The author: Both are right. The theory is wrong, but the diet works.
Blood type and disease: There are real links, such as malaria resistance, but none to food.

All four diets are whole-food diets, better than the Standard American Diet of processed food.
They remove processed food for everyone.
They remove wheat from types A, B and O, which covers most of the world’s population.
Most people (type O is the most common) are told to eat more meat and fewer carbohydrates, so the result is a low-carb whole-food diet.
It resembles Paleo, Atkins and LCHF (low carb, high fat).

Wrong assumptions about cause can still produce a sound diet.
If the belief drives lasting change in lifestyle, then it has value as change management.
Do not knock it. Support people who believe it and lose weight.
If you do not want to buy the book, just cut added sugar and processed food.

D’Adamo, P. (1997) Eat Right 4 Your Type. Putnam Adult.
Blood type diet. Wikipedia.
Sisson, M. (2013) Does your blood type determine your optimal diet? Mark’s Daily Apple.