Diets In Review: The Blood Type Hype

Follow a specific list of foods to eat and foods to avoid based on your blood type and enjoy good health and weight loss. At least, that is what Dr. Peter D’Adamo, the creator of the much criticized blood type diet boldly claims in his book “Eat Right For Your Type”. Although many people have sworn by his theories, medical opinion and research has blown his theories out the water and labeled his diet pseudo-science. Here's a brief look at D’Adamo's diet plan and the upsides and downsides to changing your lifestyle based on your blood type.

What is the blood Type Diet?

We are all born with one of four blood types, either O, A, B or AB. 

The theory holds that antigen markers in our blood type with react well or badly with certain substances in foods called lectins. By following the diet correctly, a person can enjoy greater health, less risk of disease and an ideal weight, according to the book. Originally, all human beings were blood type O, which is also the most common blood type today. D’Adamo believes that blood type Os thrive on a more meat-based diet, similar to our cavemen ancestors. The other blood types evolved later and D’Adamo equates the time of the appearance of these blood types to the types of foods eaten at that time. For example, blood type A evolved during the start of the farming era and so he believes that people with blood type A do better on vegetarian diets, for example.

The Blood Types In Summary

Blood Type O. People with this blood type would thrive on more meat-based diets that are low in grains. They should also avoid certain vegetables like cabbage, brussel sprouts and cauliflower as well as dairy products.

Blood Type A. People with blood type A thrive on vegetarian or plant based diets. They should avoid meat but can eat fish. Soya products are beneficial for this group but they should avoid most dairy products.

Blood Type B. people with blood type B can eat a more varied diet of most meats, grains and vegetables and can also tolerate dairy products. There are still a lot of foods on the avoid list though including tomatoes, avocados, coconut and lentils for example.

Blood Type AB. People with blood type AB, the rarest blood type are a combination of blood type A and B. D’Adamo suggest that they eat a mostly vegetarian diet but include some meats and fish in the diet from time to time.

Does it Work?

Like with most diet plans on the market, they tend to work by virtue of the fact that they contain natural whole foods, discourage processed food and result in a decreased food intake.

See Also: Study: Blood Type Diet Hypothesis False

One study, published in PLOS ONE in 2014, which looked at the role of the blood type diet on cardiovascular risk factor showed that the blood group diet did in fact have favorable effects but that the effects were independent of the persons blood type and were related rather to general healthy eating.

What About Lectin Theory

D'Adamo's lectin theory also remains unsubstantiated. Although lectins do exist in foods, there specificity remains in question. The so-called Nachbar Study showed that 29 of 88 foods tested did exhibit lectin like activity. However, it was found that almost all of these foods were not ABO specific and therefore do not support the theory that lectins are specific for certain blood groups.

Are There Any Benefits?

Dr. D’Adamo generally does not support the use of processed wheat products, heated oils, sugary foods and processed foods. He also suggests buying organic and grass-fed where possible. A person sitting down on these foods and eating more whole foods as he suggests is of course going to benefit.

Are There Any Downsides?

Although the blood type diet promotes natural eating and whole foods, there are many downsides to this way of eating, especially if it is followed over a long period of time. Some of the downsides include:

• Behavioral and psychological issues around food. Labeling otherwise healthy foods as “bad” can create issues for people around food. A healthy diet is a varied diet and there is no need to label an otherwise healthy food as bad because of an unproved theory.

• The diet does not make room for your preferences, lifestyle or specific health conditions. For example you might not like the foods on the allowed list or some of your favorite foods might be on the avoid list. Someone with digestive issues for example might be asked to eat lots of animal protein and avoid grains and suffer more with their symptoms as a result.

• Some of the foods on the avoid list for your blood type might contain amazing health benefits that you are missing out on. For example avoiding something like spinach, or avocado or red berries means you are missing out on their nutritional and antioxidant benefits.

• Some people might suffer specific health consequences as a result of following the diet. For example a person with blood type O who has high cholesterol could make their condition worse by eating lots of meat and avoiding grains and certain vegetables. A person with blood type A following a vegetarian diet might suffer a B vitamin or iron deficiency as a consequence.

• A family that has members with varying blood types will have a hard time cooking for a family with different lists of foods to avoid or eat.

Final Verdict?

People like the idea of a diet that is designed specifically for them. 

See Also: We Are What We Eat: The Effect Of Diet On Our Genes

Try it if you must, and by all means stop eating junk food and switch to a more wholesome diet. If the diet works for you, the most likely reasons are probably not related to your blood type but something else about the diet, like higher nutrient intake, reduced calorie intake or cutting out junk foods, rather than the blood type and food lectin interaction.