Review of Eating For Your Blood Type
You’ve probably heard of the New York Times Best Seller, Eat Right For Your Type, written by naturopath, Dr. Peter J. D’Adamo. The book is written on the premise that each of the four ABO Blood Types has a set of specific foods that boost immune function and decrease disease susceptibility, while other foods increase disease risk.
How does Dr. D’Adamo theorize that one type of food can be beneficial to one blood type yet increase disease risk in another? According to Dr. D’Adamo’s website, he believes that there are several factors that influence an individual’s optimal diet.
Adaptation: D’Adamo believes that evolutionary adaptation to diet patterns resulted in the ABO blood groups. He concludes that, over time, each of the four types has adapted to a different type of diet and set of foods.
Antiobodies: D’Adamo hypothesizes that people of different blood types have different antibodies in their blood and each blood type has a different susceptibility to diseases.
Lectins/Agglutination: According to D’Adamo, certain foods contain lectins that mimic blood group antigens and selectively cause blood agglutination (i.e. each food affects each blood group differently), and this causes diseases. D’Adamo believes that consumption of foods containing lectins incompatible with your blood type will cause agglutination of blood and ultimately lead to disease. As D’Adamo puts it, the lectins “target an organ or bodily system and begin to agglutinate blood cells in that area.”
Dr. D’Adamo reports that Type A’s thrive off of a vegetarian diet. He claims that although switching from a “meat and potato” diet to vegetables, grains and soy proteins might be difficult; Type A’s will find that it leads to a reduction in weight and an increase in energy levels. He further explains that those with the A blood type are more likely to be stressed and have higher levels of cortisol. Due to their propensity towards stress, D’Adamo recommends sticking to low-intensity exercises like yoga and tai chi.
According to Dr. D’Adamo, for Type Bs it is best to avoid corn, wheat, buckwheat, lentils, tomatoes, peanuts and sesame seeds. He reports that these foods affect the efficiency of the metabolic process, resulting in fatigue, fluid retention, hypoglycemia (low blood sugar) and weight gain. He reports that consumption of chicken can lead to strokes and immune disorders due to lectins. For optimal health and weight loss, he recommends consuming green vegetables, eggs, beneficial meats (goat, lamb, mutton, rabbit and venison), and low fat dairy.
This blood type is quite rare. According to Dr. D’Adamo, if you have this blood type, it is best to avoid caffeine and alcohol, especially during stressful situations. Foods that are said to be beneficial for weight loss include: tofu, seafood, dairy and green vegetables. Dr. D’Adamo believes that those with Blood Type AB have low stomach acid and therefore, he feels it best to avoid all smoked or cured meats. He reasons that having low stomach acids makes AB’s more likely to develop stomach cancer from those foods. Also due to low stomach acid, D’Adamo recommends not consuming starches and proteins in the same meal, as this can cause digestive distress. For optimal health, he recommends smaller, frequent meals and the consumption of some key foods: mahi-mahi, red snapper, salmon, sardines, and tuna, yogurt and kefir.
Type Os are said to thrive off of intense physical activity. Dietary wise, type O’s are believed to fare best on more of a Paleo Diet, as D’Adamo believes that this blood type has a very well-developed ability to digest meals that contain both protein and fat. He attributes this to the higher concentration of an enzyme called intestinal alkaline phosphatase and lipoprotein ApoB48 that are secreted into the digestive tract. Holding consistent with a Paleo Diet, Type Os are to avoid simple carbohydrates, especially from grains. D’Adamo suggests that these types of foods are more easily converted into fats and triglycerides in those with blood type O compared to other blood types. D’Adamo also believes that the lectins found in grains aggravate type O immune system, resulting in unwanted inflammation and autoimmune conditions.
Is it Healthy?
There are some who claim that they feel much better following The Blood Type Diet. This isn’t a surprise because generally, the recommendations for The Blood Type Diet advocate avoidance of processed foods, simple sugars, saturated fats and refined carbohydrates; foods that have been linked to increased risk of chronic disease. The majority of the Blood Type Diet is centered on whole, natural foods- foods that fuel health. Anyone will feel better when they cut out junk food and replace it with healthy food. Many of the suggestions that he has for specific blood types are good bits of advice for the majority. For example, his recommendation to consume smaller, more frequent meals is a good practice for those who need to regulate blood sugar levels and appetite. Avoidance of caffeine and alcohol during stressful situations is a good advice for anyone, as cortisol (a stress hormone) is already high during stressful situations and caffeine and alcohol can further elevate cortisol.
Here’s what Science says:
First, some of D’Adamo’s theories don’t add up to what science has proven. For example, he claims type O’s get more ulcers than type A’s, because type O’s have higher stomach acid. This doesn’t add up to what research points to as the cause of ulcers: H. pylori, a bacterium. Barry Marshall and Robin Warren the two discoverers of this organism have were awarded the Nobel Prize for their groundbreaking discovery.
Researchers from the University of Toronto conducted a study to test the benefits of adherence to various Blood Type Diets. Findings were published in PLOS One. The findings were as follows: adherence to the Type-A diet (vegetarian) was associated with lower BMI, waist circumference, blood pressure, serum cholesterol, triglycerides, and insulin. Adherence to the Type-AB diet was also associated with lower levels of blood pressure, serum cholesterol, triglycerides, and insulin. BMI and waist-circumference were not impacted. Adherence to the Type-O diet was associated with lower triglycerides. The study did not find significant changes for the Type-B diet. Despite these benefits of following the Type A, AB and O diets, researchers reported that matching the ‘Blood-Type’ diets with the corresponding blood group did not change the effect size of any of these associations. They concluded that, “ adherence to certain ‘Blood-Type’ diets is associated with favorable effects on some cardiometabolic risk factors, but these associations were independent of an individual’s ABO genotype, so the findings do not support the ‘Blood-Type’ diet hypothesis.”
If you’re curious what Dr. D’Adamo has to say about your blood type, by all means, read the book. If you’d like to do a self-experiment, you’re more than welcome. However, if the recommendations don’t seem feasible, or force you to eat a way that just doesn’t resonate with you, don’t feel like you’re going to increase your disease risk by not adhering. A 2013 study published in the American Journal of Clinical Nutrition found no scientific evidence supporting the efficacy of the Blood Type Diet. What research does support is that consumption of highly processed fatty foods, simple sugars and refined carbohydrates leads to increased inflammation and does increase risk of diseases such as Type 2 diabetes, cardiovascular disease, obesity, hypertension, among others. If you stick to a whole-food diet of lean proteins, plenty of vegetables, healthy fats, with moderate amounts of beans/lentils/legumes, whole grains and dairy (if you don’t have a sensitivity), you’ll be eating to fuel your health. Always be mindful of portion size and don’t consume more than you need. Excess consumption of anything (even healthy foods) can lead to stomach discomfort and eventually weight gain.