With greater recognition and scientific understanding of the body’s functionality in relation to nutrition, the number of accompanying diet trends also increases. One recent fad diet is the Blood Type Diet, which caters to nutrition and balance based on the blood types you possess. Though there is not yet empirical research to support the benefits of this diet, many do believe in its naturopathic benefits and adhere to its restrictions. But where did the Blood Type Diet come from?

History of the Blood Type Diet

Peter J. D’Adamo, a naturopath and physician, and the founder of the Blood Type Diet, developed the framework in the mid-1990s. D’Adamo argues that your blood type is a key component in the functionality of your body, including the digestive system and metabolism. He claims blood type can determine your reaction to stress, processing of food with gut bacteria, and the likelihood of contracting certain diseases. His diet, therefore, attempts to mitigate risks he claims stem from your particular blood type.

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Scientific Basis?

The founders of the blood type diets claim that molecular mimicry and adhesion (amongst other factors) demonstrate a scientific basis for the blood type theory. Proponents suggest some molecules will change their chemical composition to mimic the molecular structure of the blood. According to this field of thought, certain antigens interact more or less harmoniously than others, depending on your blood type. The antigens that interact eagerly fuse more readily with your blood cells (adhesion), thus placing you at risk for some diseases.

The “Lectin Connection”

D’Adamo claims our blood types are ancient markers of preference and taste. When we eat food, proteins are released into the body, including lectins. Lectins are sticky proteins that bind together molecules in different organs. However, D’Adamo asserts, if we eat foods with certain amounts of lectins when we have an incompatible blood type, we risk these lectins attaching to healthy tissue.

Dangers of Agglutinins

Lectins are agglutinins, types of proteins that “glue” molecules together. Another very powerful and dangerous agglutinin is the poison ricin, which, when deployed inside the body, quickly binds together red blood cells to form clots. This stops regular circulation and can kill instantaneously. D’Adamo concedes that lectin is not nearly as dangerous, but it can motivate digestive problems, particularly after eating.

Secretor or Non-Secretor?

Another central claim in D’Adamo’s theory about blood type diets is secretor/non-secretor separation. According to D’Adamo, in the case of secretors, the blood type is secreted into different areas of the body such as the mucous glands, saliva, and respiratory cavities. Non-secretors do not transmit their blood type. D’Adamo claims that nearly 80 percent of the population fall into the secretor category.

Fatty Foods

D’Adamo claims the enzymes secreted after eating certain types of fats demonstrate the validity of his blood type diet. Some diets promote “good fat” nutrition, while others advise removing fats from the diet. D’Adamo claims your blood type determines your unique level of intestinal alkaline phosphatase (IAP), a key enzyme in the digestion and absorption of fat. His research concludes that blood types O and B may produce three to five times the average level of IAP.

Blood Type A Diet

D’Adamo links personality and blood type. He claims those with type A blood are more detail-oriented, good listeners, and creative. Therefore, in addition to a lifestyle change, he recommends more protein at the beginning of the day and less at the end, smaller, more frequent meals, not eating when anxious, and chewing food more carefully. This last recommendation is due to D’Adamo’s belief that A types have less stomach acid.

Blood Type B Diet

D’Adamo suggests people with blood type B are more creative, easygoing, and flexible. These blood types gain weight more readily when a diet is based on corn, wheat, lentils, and tomatoes. Instead, he suggests including game meats, like venison and rabbit, and eliminating chicken. He also recommends low-fat dairy products and leaner meats.

Blood Type O Diet

According to the blood type diet, type O individuals benefit most from physical exercise, which helps maintain health and mental balance. In addition, they tend to have an ample supply of stomach acid, a necessary component in digestion. Therefore, D’Adamo recommends a high-protein (particularly animal protein) and low-carb (particularly grains) diet, as type O bodies are more capable of breaking down the fats in proteins, and more likely to expend less effort eliminating the sugars in the carbohydrates.

Blood Type AB Diet

Type ABs are spiritual and intuitive, according to D’Adamo, and yet often feel deprived of community or a sense of belonging. Therefore, people with this blood type are advised to avoid caffeine and alcohol, particularly at stressful times. He also recommends tofu, seafood, dairy products, and green vegetables to help the low amounts of stomach acid produced in the gut.