What science says about Blood Type Diet For Allergy

Published 29 June 2020

Peter D’Adamo, the creator of the blood type diet, claims that there is a link between blood type and allergies. Accordingly, each blood type can develop or exacerbate allergies when eating foods that trigger an unnecessary immune response.

Supporters of the diet claim that some individuals are more at risk for allergies than others due to their blood type. They also claim that certain blood types should avoid specific foods that they cannot metabolize well.

These foods can increase the amount of fat in their bodies. The fats trigger an unnecessary immune response because the body perceives the fats to be a foreign substance that imposes a threat to it. This increases the risk of developing allergies.

On the other hand, opponents of the diet claim that there’s no scientific evidence to support the blood type diet hypothesis. Research has found that there is no link between the blood type diet or and the decreased risk of any disease. 

In addition, scientists have not researched the blood type diet and its effects on allergies. Thus, they do not know if the blood type diet is an effective treatment for allergic diseases.

Furthermore, opponents of the diet believe that the blood type diet might improve a person’s health, but this is because it encourages people to eat healthy and organic foods. They argue that all of the blood types metabolize foods in the same way.

Thus, a person’s risk for a disease such as allergies does not depend on whether an individual eats specific food tailored according to blood type.

Opinion in favor of following the blood type diet to treat allergy:

Peter D’Adamo, the creator of the blood type diet, claims that there is a link between blood type and allergies. Each blood type can develop allergies when consuming foods that trigger an unnecessary immune response and cause inflammation. Thus, the blood type diet recommends that each blood type eliminates foods that stress the body to prevent allergies.

There are some studies that explore the link between allergies and blood type or plant lectins and blood type. The 1991 study, “Dietary Lectins: Blood Types and Food Allergies,” found that harmful lectins can be toxic and cause allergies in certain blood types because they disrupt the digestive system’s function and cause agglutination in the body.

However, the study also concluded that people of similar blood types might not have the same immune response to the same lectin. For instance, some people with a similar blood type may have an extreme reaction to a lectin, while others might have very little to no immune system response to that same lectin.

Therefore, D’Adamo’s hypothesis about the functions of blood type specific lectins in the body is partially true. While it is true that some blood types have specific reactions to certain lectins, people of the same blood type might have different reactions to lectins due to different antibody responses.

Opinion against following the blood type diet to treat allergy:

Many medical experts believe that there may be a link between an individual’s blood type and the risk of allergies. However, there is insufficient scientific evidence to support the hypothesis that the blood type diet, or eating particular foods according to our blood type, treats or reduces these allergies.

Opponents of the diet argue that even though the blood type diet prescribes different foods for each blood type, the foods affect all blood types in the same manner. In a 1980 study, “Lectins in the United States diet: a survey of lectins in commonly consumed foods and a review of the literature,” conducted by Nachbar and Oppenheim shows that lectins have agglutination properties, and lectins in legumes can be harmful to the human body.

However, the study does not indicate that different blood types have different reactions to lectins. Therefore, experts believe that the blood type diet bases its explanation on valid scientific evidence. However, it twists the scientific rationale to make false promises because people do not have different reactions to specific foods due to their blood type.

Experts also claim that the blood type diet is not supported by scientific evidence. In 2013, a study by Cusack et al. titled, “Blood type diets lack supporting evidence: a systematic review,” analyzed studies presenting data about blood type diets.

They found that these studies were poorly designed because the experiments lacked a control group of people following a standard diet. This works against the diet because it was difficult for researchers to compare the responses of people following the blood type diet to those following the standard calorie restriction diet. Therefore, researchers could not tell if people’s diseases improved because they followed the blood type diet or because of other factors. 

In addition, there are no studies that specifically examine the effect of the blood type diet on allergies. There are some studies that show lectins may exacerbate allergies or produce allergy sensitivity. However, none of the studies included blood type as a distinguishing factor that affected allergy risk. As a result, opponents of the diet cannot validate D’Adamo’s hypothesis.

Dr. Andrew Weil, a Harvard Medical School graduate and advocate for alternative medicine, argues that there is no link between lectins and blood type. Peter D’Adamo responded to Dr. Weil’s claims on his website, maintaining that Dr. Weil’s argument was built on “incorrect assertions” about the blood type diet.

The diet’s opponents attribute the blood type diet’s success when treating allergies to healthy eating habits, such as eating organic fruits and vegetables and avoiding processed meats, high sugar foods, and refined carbohydrates.

Healthcare experts maintain that people of all blood types should eat organic fruits and vegetables to help fight allergies because they contain fiber, which maintains gut health and boosts immune system function. Some vegetables like Swiss chard or onions also contain a pigment called quercetin, which acts as a natural antihistamine, preventing allergic reactions.

Meanwhile, opponents of the blood type diet for allergies argue that the diet restricts all kinds of processed meats, high sugar foods, and refined carbohydrates, which contain added sugars. These foods are known to affect the immune system negatively and can cause inflammation. Processed meats also contain cytokines or signaling proteins that trigger an immune response as well as the production of IgE molecules that release histamine when in contact with an allergen.

Thus, opponents argue that restricting processed meats and high sugar foods is the reason why the blood type diet may be beneficial for treating allergies, not the blood type diet per se because one’s reactions to food does not differ according to blood type.