The blood type diet has gained ground in recent years as a personalized diet proposition based on an individual’s blood type. So, the central idea is that individuals with A, B, AB or O blood would react differently to certain foods. From this point of view, it would influence weight, disposition and even certain health problems. This dietary model is presented as a way of organizing the daily menu, choosing what would be most “compatible” with the body based on blood group.
Although popular on social media and in some doctors’ offices, the blood type diet still raises doubts about its scientific basis and how it should be applied. Many people listen to ready-made recommendations, but do not understand where the lists of allowed or restricted foods come from. So, before adopting it, it is important to understand how this method came about, what it offers and what precautions may be necessary.
What is the blood type diet and how did it come about?
The blood type diet emerged in the 1990s and became famous thanks to the hypothesis that the development of types A, B, AB and O occurred at different times in human history. Based on this hypothesis, the breeder associated each blood group with a “most suitable” feeding style. Thus, group O was linked to hunting habits, with greater meat consumption. Group A, agricultural societies, with more cereals and vegetables and group B, nomadic populations, with an emphasis on dairy products. Finally, Group AB, a combination of Group A and B guidelines.
This reasoning led to the construction of tables of foods in a list as “beneficial”, “neutral” or “to avoid” for each blood group. Furthermore, the proposal is also based on the action of lectins. These are proteins found in certain foods that could, in theory, interact differently with red blood cells of each blood type. In this way, the menu would be created seeking to reduce possible reactions between lectins and blood cells.
What are the recommendations for each blood group?
In practice, the blood type diet works as a guide for recommended or restricted foods. Although details may vary by source, some guidelines tend to be repeated. In general, the diagram is as follows:
- Type O: increased consumption of lean meats, fish and certain vegetables; limit dairy products, wheat and certain grains.
- Type A: encourage a diet closer to vegetarianism, favoring vegetables, fruits, whole grains and legumes; moderation in the consumption of red meat.
- Type B: inclusion of dairy products, meats and various vegetables; restriction on certain grains, such as wheat and corn, and certain processed foods.
- Type AB: combination of recommendations from groups A and B, with an emphasis on vegetables, seafood, certain dairy products and reduction of very fatty meats.
Although these guidelines are general, each line of material on the subject generally presents detailed lists of foods identified as most suitable for each group. In many cases, this personalization is presented as a way to facilitate weight loss, reduce digestive discomfort and better organize meals throughout the day.
Does the blood type diet really work?
When discussing the effectiveness of a blood type diet, the central point tends to be the presence or absence of solid scientific evidence. Until 2025, studies carried out in different countries evaluated the relationship between blood type, dietary habits and health indicators, such as cholesterol, blood sugar and body weight. Recurrently, these studies have not identified specific benefits directly linked to the combination of diet and blood type.
In many cases, people who follow a blood type diet report weight loss or improvement in certain tests. However, this tends to be associated with general habit changes, such as reducing ultra-processed foods, increasing fruit and vegetable consumption, and portion control. In other words, the positive impact generally comes from adopting a more organized and balanced diet, and not necessarily from an adjustment based on blood type.
Research reviewed by independent teams has shown that to date, there is no strong evidence that blood type determines which foods would be ideal for each individual. Thus, the blood type diet It is considered, by a large part of the scientific community, as a still unconfirmed hypothesis, which requires more controlled and long-term studies.
What precautions should be taken when considering this type of diet?
When considering a blood type diet, certain precautions are generally necessary. First, some versions of the diet may exclude important food groups, such as dairy, legumes, or whole grains, without assessing the individual’s health context. Restrictions without professional supervision can lead to nutrient deficiencies, such as calcium, iron or B vitamins.
Additionally, the exclusive focus on blood group it ignores factors recognized in modern nutrition, such as physical activity level, pre-existing medical conditions, medication use, age group and cultural preferences. An adult with diabetes, for example, may need different dietary adjustments than someone without this diagnosis, regardless of blood type. The same goes for pregnant women, the elderly or people being treated for chronic illnesses.
Concretely, when evaluating a diet, certain points are generally considered essential:
- Nutritional adequacy: balanced presence of carbohydrates, proteins, quality fats, vitamins and minerals.
- Flexibility: possibility of adaptations according to routine, food culture and access to food.
- Long-term durability: ability to maintain eating habits without causing physical or social exhaustion.
- Professional support: supervision by a nutritionist or doctor to analyze the tests and adjust the menu.
Can the blood type diet play a role in your eating routine?
Even without precise scientific confirmation, some people use the blood type diet as a starting point for planning their meals. In some cases, the method serves to encourage reading labels, cooking more at home, and paying attention to the body’s own reactions to certain foods. These movements tend to favor more planned and less impulsive choices.
For those interested in the subject, a common approach is to face the blood type diet as a road map among several possibilities, and not as the only alternative. The menu can be adapted by integrating balanced diet principles recognized by current studies, such as increased consumption of vegetables, fruits, legumes, whole grains and sources of unsaturated fats.
Ultimately, blood type is just one of many elements of the human body. Developing a meal plan tends to be more coherent when you consider the whole picture: medical history, updated exams, work routine, sleep, physical activity and individual preferences. Within this broader framework, the blood group diet can be calmly analyzed, adjusted if necessary and always evaluated in the light of available evidence.
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