The basic theory behind the diet is that our blood type creates differences in our physiology that are substantial enough to warrant adjustments in lifestyle. For example, on his website D’Adamo describes Type O as the “oldest of the blood types” writing that those with type O blood display traits like “exceptional strength, a lean physique, and a productive mind” but also an “overactive fight or flight response reminiscent of early survival instincts.” He then goes on to say that type A blood types entered the genetic landscape at the time of animal domestication and agriculture. “Thriving on a mostly vegetarian diet rich in soy protein, fruits, and vegetables, Blood Type A individuals are sensitive, creative, analytical thinkers,” he writes.
According to a Harvard Health Blog (2) on the topic, the Blood Type Diet gives the following recommendations for each blood type:
- Those with type O blood should choose high-protein foods and eat lots of meat, vegetables, fish, and fruit but limit grains, beans, and legumes. To lose weight, seafood, kelp, red meat, broccoli, spinach, and olive oil are best; wheat, corn, and dairy are to be avoided.
- Those with type A blood should choose fruit, vegetables, tofu, seafood, turkey, and whole grains but avoid meat. For weight loss, seafood, vegetables, pineapple, olive oil, and soy are best; dairy, wheat, corn, and kidney beans should be avoided.
- Those with type B blood should pick a diverse diet including meat, fruit, dairy, seafood, and grains. To lose weight, type B individuals should choose green vegetables, eggs, liver, and licorice tea but avoid chicken, corn, peanuts, and wheat.
- Those with type AB blood should eat dairy, tofu, lamb, fish, grains, fruit, and vegetables. For weight loss, tofu, seafood, green vegetables, and kelp are best but chicken, corn, buckwheat, and kidney beans should be avoided.
If this all seems a little far-fetched to you, you wouldn’t be the first to think so. In fact, one german scientist is quoted as saying “it is difficult not to perceive the whole thing as a crass fraud.” (3)
The Blood Type Diet claims to help the body function ideally by supporting healthy digestion and high energy levels. D’Adamo even says that by following your Blood Type Diet plan, you can prevent diseases like cancer and cardiovascular disease. Research has been done on the blood type diet, but none of it was conclusive. For example, a 2013 study (4) analyzed existing medical literature on the benefits of these diets and found no benefit; another study published in 2014 showed that people following any of the blood type diets experienced improvements in cardiometabolic risk factors (5) like cholesterol and blood pressure but that these improvements could actually be linked to blood type. Not to mention, research has also come out proving that type O is not actually the most ancient blood type — type A is (6). Unfortunately, when you dive deeper into the basis of the Blood Type Diet and the research behind it, there are quite a few gaps and holes.
That said, there is also research showing that certain blood types do put humans at risk for specific health issues. For example, the authors of a 2011 study (7) concluded that “…studies have conclusively linked the ABO locus to pancreatic cancer, venous thromboembolism, and myocardial infarction…These findings suggest ABO’s important role in determining an individual’s susceptibility to such diseases.” In addition, certain foods do seem to affect blood types differently. For example, the lectins found in raw lima beans cause issues in those with type A blood (8) but not with other blood types.
Therefore, it’s not a huge leap to say that in the future, when we know more about each blood type, we’ll find that certain food sensitivities are, in fact, more common in some than in others. That said, the research to back up the very specific recommendations that D’Adamo gives in his book just doesn’t exist.
From where I’m sitting, the nutrition and lifestyle advice in the Blood Type Diet is universally healthy, regardless of blood type. For example, D’Adamo advocates for eating real, whole foods and avoiding universally inflammatory foods like dairy, wheat, and certain lectin-containing beans and legumes. He also takes a holistic approach to healthy, giving tips for exercise and stress management. Personally, I’m all for that.
Therefore, if you want to follow the blood type, it won’t hurt. In fact, it may benefit your health in more ways than one — just know that the benefits don’t appear to be connected directly to your blood type.
If you want to learn more about your own health case please check out our consultation process. We offer in person as well as phone and webcam consultations for people across the country and around the world.