The blood group diet originated from a 1996 book by naturopathic physician Peter D'Adamo, in which it was proposed that choosing foods based on one's blood type can improve health. Despite the book's popularity, the blood-group diet lacks scientific evidence to support its claims.
The theoretical basis of blood group diet is that blood type A should be more vegetarian, blood type O should be suitable for a diet high in animal protein, blood type B should eat more dairy products, and people with blood type AB should combine the dietary characteristics of type A and type B.
How does the blood type diet claim to work?
Blood group is mainly determined by the antigen (substance that triggers the immune response) present on the surface of red blood cells, i.e., A antigen, B antigen, or both, thus forming four blood groups: A, B, AB, and O. This diet is based on the evolutionary hypothesis that blood type affects the digestion and absorption of food, and that a corresponding diet can provide health benefits.
Early studies on the association between blood type and health have shown that people with blood type O have a slightly lower risk of ischemic heart disease (coronary artery disease) than other blood types. A 2016 meta-analysis supported this view, showing that people with blood type O had an approximately 15% lower risk of coronary heart disease. At the same time, individuals with blood type A may be at higher risk of total cholesterol and LDL ("bad" cholesterol) levels.
Dietary recommendations for each blood type
Type O blood
Meat (including red meat), fish, vegetables (such as broccoli and spinach), and fruits are recommended, limiting grains, legumes, and legumes. Avoid wheat, corn, and dairy products when losing weight.
Type A blood
Fruits, vegetables, tofu, seafood, turkey, and whole grains should be consumed, and red meat should be avoided. Avoid dairy, wheat, corn, and red beans when losing weight.
Type B blood
Enjoy a variety of foods, including meat, dairy, seafood, grains and leafy greens. Chicken, corn, peanuts, and wheat should be avoided when losing weight.
Blood type AB
Suitable foods include dairy products, tofu, lamb, fish, cereals and vegetables. Chicken, corn, buckwheat and red beans should not be eaten when losing weight.
The recommended dietary pattern of blood type A, which is rich in fruits and vegetables and whole grains, and restricts red meat, is beneficial not only for people with blood type A, but also for people with blood types O, B, and AB. A 2014 study showed that dietary advice for different blood types had health effects, but it was not related to blood type. Regardless of blood type, following a dietary pattern rich in vegetables, fruits, and whole grains can help cardiovascular health.
What does the scientific community think of these assertions?
The health benefits of the recommended foods are derived from the food itself, not from blood group specificity.
- People with a similar blood type A eating pattern (more fruits, vegetables, grains, less meat) tend to have better cardiometabolic markers, such as lower BMI, waist circumference, lipid levels, and insulin resistance, regardless of blood type.
- Blood type O-like dietary recommendations (emphasis on meat, fruits and vegetables, and restriction of grains) are associated with lower triglyceride levels, which are also independent of individual blood type.
The theory of choosing foods according to blood group to benefit from the blood group diet lacks scientific basis. Nutrition experts recommend that it is more reasonable to choose a diet based on your personal health and family history. The Mediterranean diet, the DASH diet and certain anti-inflammatory diets all have more scientific evidence to support their health benefits.
References——
- Wang J, García-Bailo B, Nielsen DE, El-Sohemy A. ABO genotype, ‘blood-type’ diet and cardiometabolic risk factors. Ashton N, ed. PLoS ONE. 2014; 9(1):e84749. doi:10.1371/journal.pone.0084749
- Condemi S, Mazières S, Faux P, Costedoat C, Ruiz-Linares A, Bailly P, Chiaroni J. Blood groups of Neandertals and Denisova decrypted. PLoS One. 2021; 16(7):e0254175. doi:10.1371/journal.pone.0254175
- Barnard ND, Rembert E, Freeman A, Bradshaw M, Holubkov R, Kahleova H. Blood type is not associated with changes in cardiometabolic outcomes in response to a plant-based dietary intervention. Journal of the Academy of Nutrition and Dietetics. 2021; 121(6):1080-1086. doi:10.1016/j.jand.2020.08.079