What science says about Blood Type Diet For Dementia

Published: June 2020

The blood type diet for Alzheimer’s disease is a highly debatable topic.

On one hand, Peter D’Adamo, the creator of the blood type diet, claims that there is a link between blood type and the risk of developing Alzheimer’s disease. Accordingly, each blood type can develop Alzheimer’s disease when eating foods that increase cortisol levels or foods that contain harmful lectins. 

Supporters of the diet claim that some individuals are more at risk for Alzheimer’s disease than others due to their blood type. They also claim that certain blood types should avoid specific foods that contain harmful lectins.

These foods with harmful lectins cause an agglutination reaction that triggers an unnecessary immune response, leading to inflammation around the brain’s neurons. The lectins can also damage neurons and interrupt cell communication, leading to memory loss.  These factors increase the risk of developing Alzheimer’s.  

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 the decreased risk of Alzheimer’s or any other disease. In addition, scientists have not researched the blood type diet and its effects on Alzheimer’s. Thus, they do not know if the blood type diet is an effective treatment for it. 

Furthermore, opponents of the diet believe that the blood type diet might improve people’s health, but only because it encourages them to eat healthy and organic foods. They also argue that all of the blood types metabolize foods with harmful lectins in the same way. Therefore, the blood type diet is not based on scientific grounds. 
Thus, people’s risk for Alzheimer’s does not depend on eating specific foods tailored to their blood type.

Opinion in favor of following the blood type diet to treat Alzheimer’s disease:

Supporters of the blood type diet for aging diseases claim that there is a link between blood type and Alzheimer’s disease. According to them, each blood type can develop Alzheimer's if they consume foods that increase cortisol levels.

Also, specific blood types are more at risk for Alzheimer’s if they eat foods that contain harmful lectins. Both of these factors damage brain cells, interrupt brain cell communication, block blood flow to the brain, and cause inflammation around the neurons.

When discussing the link between lectins and Alzheimer’s disease, D’Adamo mentions that lectins have been used to help locate instances of reactive plasticity in the brain. The 2001 study, “O-Glycosylation in Sprouting Neurons in Alzheimer Disease, Indicating Reactive plasticity,” proved that researchers used lectins to determine how reactive plasticity occurs.

Scientists observed how lectins bind to the sugars in the brain to determine how the brain changes its structure when proteins come in contact with sugars on the neurons. While this study proves that lectins model how neuron damage occurs in Alzheimer’s disease, it does not address the issue of diet or whether specific blood types need to avoid specific lectins. Therefore, D’Adamo’s theory is based on science, but it is not substantiated by any evidence.

Furthermore, research shows that clotting factors in the blood increase the risk of developing Alzheimer’s diseases. The study, “ABO blood type, factor VIII, and incident cognitive impairment in the REGARDS cohort,” indicated that blood type AB might be more at risk for Alzheimer’s disease because type AB individuals have higher levels of clotting factors in their blood.

However, the study did not test for blood clotting factors, the presence of lectins, and the risk of Alzheimer’s according to blood type. Scientists do not know what role lectins play in the development of Alzheimer’s disease. Therefore, the blood type diet hypothesis is not completely supported by scientific evidence.

Opinion against following the blood type diet to treat Alzheimer’s disease:

Many medical experts believe that, although there may be a link between an individual’s blood type and the risk of developing Alzheimer’s, 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 the risk of arthritis.

Opponents of the diet argue that the blood type diet does not prescribe foods that affect each blood type differently. This is because lectins in food react with all blood types in the same manner.

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, all blood types react to lectins in a similar manner. Therefore, experts believe that the main theory behind the blood type diet is false.

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 Alzheimer’s disease.  While some studies show that blood type may be a factor in determining Alzheimer’s risk, other studies indicate otherwise. 

For instance, in the 2015 study “ABO Blood Group and Dementia Risk – A Scandinavian Record-Linkage Study,” Vasan et al. found no link between blood type and the risk of developing Alzheimer’s disease. As a result, opponents of the diet cannot validate the blood type diet hypothesis.  

The diet’s opponents attribute the blood type diet’s success in treating Alzheimer’s 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 Alzheimer’s because they contain antioxidants that increase blood circulation to the brain and have anti-inflammatory properties that help maintain brain health.

Experts also argue that people should avoid eating sugar and refined carbs because they contain added sugars which increase the accumulation of beta-amyloid in the brain, leading to Alzheimer’s. Processed meats also contain nitrosamines, which are chemical compounds that induce the liver to produce fats that are toxic to the brain. All of these foods also cause inflammation which is harmful to the brain.

Thus, opponents argue that although D’Adamo uses scientific explanation to back up the blood type diet for Alzheimer’s, he twists the science to deliver fictive promises as specific foods do not affect particular blood types in different ways. Everyone, regardless of blood type, reacts to specific foods in the same way.