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Are you looking for a new diet to try? You might be thinking the blood type diet is the way to go as there are quite a few establishments in the country pushing it. It sounds perfect – eat according to your specific blood type, and you will lose weight while gaining other health benefits like a healthy heart in the process. Perhaps you are thinking “a doctor invented it after all and his book sold over 7 million copies, landing it on the New York Times bestseller list, so it must be true, right?”      

What is the blood type diet? 

A naturopathic doctor introduced the blood type diet, Peter D’Adamo, in his book Eat Right For Your Blood Type, published in 1996. In this diet, you only eat foods considered appropriate to your blood type (A, B, AB or O). The diet provides a list of approved foods considered beneficial to each blood type, foods that should be avoided and foods branded ‘neutral’. When Dr Karl Landsteiner discovered that there are four blood types, he also found that blood types don’t work well together if they are mixed due to their antibodies. When combined, they undergo agglutination, where they clump together. According to Dr D’Adamo, certain foods cause our blood cells to experience the same process when not deemed compatible with a person’s blood type due to lectins (sugar-binding proteins) in some foods. 

How and what should I eat when on the blood type diet: 

Based on this diet, people with a blood type O are the ancestral blood group. They should eat primarily foods high in animal protein like meat, fish, and poultry, limiting certain vegetables and avoiding beans, grains and dairy. People with blood type A are advised to follow a vegetarian diet with no dairy, fish, poultry, eggs, or nuts & seeds. This blood group evolved when humans settled down into agrarian societies. With blood type B, you can eat from most food groups (meats, grains, dairy, eggs, vegetables etc.) while only cutting out processed foods. Lastly, blood type AB allows you to mix between type A and type B diet foods. 

Let’s look at what the science tells us: 

Science tells us that it does not look suitable for blood type diets. Basic human physiology does not allow our digestive processes or energy balance to change merely based on our blood type. If this were so, it would be undeniable. The picture D’Adamo draws for us with these diets is not supported by scientific evidence. There are minimal observational and intervention studies on these diets, which makes the evidence in favour of these diets weak. According to a cross-sectional study done by Wang et al. in 2014, the studied participants’ compliance to the four blood type diets was examined to establish a link between blood type diets and a person’s cardiometabolic health (for example, cholesterol levels, waist circumference). They found that blood type diets are associated with positive health effects, but these benefits were not connected to the person’s blood type, meaning the study’s findings do not favour blood type diets.       

In a 2020 study published by Barnard et al. in the Journal of the Academy of Nutrition and Dietetics, they found that a      person’s blood type makes no difference to the diet they should follow. Furthermore, in a systematic review published by Cusack et al. in 2013, it was found that there is no evidence that the blood type diet is valid. 

In a nutshell 

Your blood type does not determine the best diet for your health and body weight goal, as a person’s blood type has nothing to do with their diet. The research shows us that following the blood type diet does hold health benefits as many diets can. But blood type diets lack scientific evidence and it is not recommended to cut out groups of foods from your diet as they all play a vital role in health and the risk of nutrient deficiencies or excessive consumption is high.

Instead, choose a balanced diet with lots of variety from fruits and vegetables, whole grains (brown rice, couscous), beans & peas, lean meats, healthy fats (like avocados, olive oil), and low-fat dairy options. At the same time limit processed foods & beverages and those high in sugar and saturated fat. Combine this with at least 30 minutes of exercise per day, 4 times per week for a healthier 2022. 


Barnard, N.D., Rembert, E., Freeman, A., Bradshaw, M., Holubkov, R. and Kahleova, H., 2021. 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, 121(6), pp.1080-1086. 

Cusack, L., De Buck, E., Compernolle, V. and Vandekerckhove, P., 2013. Blood type diets lack supporting evidence: a systematic review. The American journal of clinical nutrition, 98(1), pp.99-104. 

Wang, J., García-Bailo, B., Nielsen, D.E. and El-Sohemy, A., 2014. ABO genotype, ‘blood- type diet and cardiometabolic risk factors. PloS one, 9(1), p.e84749. 


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