The Blood Type Diet is based on using blood type to determine which foods are most compatible with different body chemistries.
A naturopathic doctor named Peter D’Adamo published the book Eat Right for Your Type in 1996; the book hit the New York Times Bestseller list, and the diet has been popular ever since.
Dr. D’Adamo believes that everyone should not eat the same thing, and he carries that idea even further to propose that people with different blood types do better with different kinds of exercise, supplements, and even medications.
Some claim following Dr. D’Adamo’s guidelines saved their lives.
Also referred to as the blood group diet, this approach advocates choosing dietary components according to blood types; for example, people with type A blood would eat differently than people with type O blood.
This takes into consideration ancestral genetic traits that include what foods our forebears ate that contributed to cultivating good health.
Let’s get a clear idea of the basics and reasoning behind diet plans for each blood type, as well as existing evidence on how it works.
Outline of the Blood Type Diet
Each blood type has recommendations for foods that should be included in the diet, and foods that should be avoided, as well as foods that affect body chemistry in a neutral manner.
This way, anyone following the diets can make selections that support his or her own physical make-up through food choices.
Each blood group diet is based on whole, real foods, which could make it more challenging to determine if it’s the type of food, or the quality of food, that leads to improvements when compared to a typical American diet running heavy on processed foods.
Here are a few do’s and don’ts for each blood type:
- Blood type O: this high-protein approach is referred to as “The Hunter.” It is much like the paleo diet, with an emphasis on proteins like meat, poultry and fish; certain vegetables and fruits are included, but very few grains, diary or legumes.
- Blood type A: this plan is “Agrarian” in nature, and can be mostly vegetarian. Individuals with type A blood are advised that meat is toxic to their systems, and the diet focuses on foods from plant sources.
- Blood type B: called “The Nomad,” people with type B blood do well with plant foods, dairy products, and most meats, with the exception of chicken and pork. A few of the foods on the “avoid” list include lentils, wheat, corn and tomatoes.
- Blood type AB: referred to as “The Enigma,” those who have type AB blood are said to thrive on a mixture of foods that work for both type As and type Bs. Recommendations for foods to include are dairy, grains, beans, tofu and seafood; they should avoid chicken, beef, beans and corn.
To understand the reasoning behind the guidelines, you need a little information on lectins, which are anti-nutrients belonging to a group of proteins with the capacity to bind sugar molecules.
Lectins can negatively impact gut lining and digestive processes; the reaction to lectins varies between blood types and different foods. The diet theory claims that when we eat foods containing lectins that aren’t compatible with our blood type, it can lead to the clumping of red blood cells called agglutination. (1)
Here’s an example: raw lima beans can affect red blood cells in type A individuals, but not in those with other blood types. (2)
However, with the exception of certain raw legumes, dietary lectins react with all ABO blood types. (3)
Since legumes are soaked and cooked prior to eating, the fact that lectins in raw legumes may cause changes in red blood cells probably does not have any practical relevance. (4)
Scientific Evidence on Blood Type Diets and Health
Ongoing research in the field of ABO blood types has resulted in a respectable amount of new information over the last few years, and evidence indicates the risk of developing certain diseases varies greatly between people with different blood types. (5)
Studies show those with type O blood are at lower risk for developing heart disease, which is in accordance with the informational material contained in Dr. D’Adamo’s book. (6) And anyone with type O blood is more likely to have problems with stomach ulcers, and could be more susceptible to inflammatory diseases. (7)
However, there is no indication whether these statistics are connected to dietary choices and habits.
An observational study tracking health markers in nearly 1500 young adults following a typical type A diet that included plenty of vegetables and fruits indicated positive overall changes. The improved markers were noted in all participants, rather than just those with type A blood. (8)
In 2013, researchers reviewed data from more than a thousand studies without finding any well-designed trials that zeroed in on the effects of blood type diets. (9)
Only 4 studies were associated with the blood type approach to dietary choices, and scientists determined these were flawed in integral manners. One study in this area of research appeared to contradict the basis of the blood type diet recommendations. (10, 11, 12)
It’s important to keep in mind that everyone is different, and while some diets work well for certain people, others don’t thrive on them.
Most of us know people who prefer eating vegetarian style while maintaining excellent health, while others include plenty of meat, fish and poultry in their diet, with similar good results.
You may have tried the blood type approach to diet, and experienced improvements in health; this may not necessarily mean the good results were due to excluding certain foods and focusing on others. It could mean only that you found a way to nourish yourself that was a good match for your metabolism.
As noted above, the majority of foods recommended for all blood types are whole and natural, rather than processed; this feature alone could account for many positive changes, especially if processed foods were a large part of the diet before adopting the new pattern.
Since there is so little evidence in regard to how following a diet designed to cater to specific blood types can affect overall health, drawing any conclusions about the efficacy of such plans is not possible at this point.
Summary: Many people who have tried the blood type diet believe it’s been beneficial for them, and there’s no evidence that it’s not. If you’re observing the guidelines and like the results, there’s no harm in continuing to follow the plan.