The Blood Group Diet: Myth Or Science

By Raphael Obu Nyarkotey

As I did promised my readers on the blood group diet, I bring to you an Evidence-Based Review on this media hyped diet restrictions being campaigned by some experts. I realized that lots of people have fallen prey to this campaign.

I believe in evidence-based medicine and not theoretic medicine. I do not support medicine based on emotions; irrespective of the type of practice: being alternative, Traditional or conventional medicine. I believe in objectivity devoid of subjectivity. You see a diet called The Blood Type Diet has been popular for almost two decades now. Proponents of this diet suggest that your blood type determines which foods are best for your health. There are many people who swear by this diet and claim that it has saved their lives. But what are the details of the blood type diet, and is it based on any solid evidence? This is the basis of my article. Let’s have a look.

The Genesis of Blood Type Diet
The blood type diet, also known as the blood group diet, was popularized by a naturopathic physician called Dr. Peter D’Adamo in the year 1996. His book, Eat Right 4 Your Type, was incredibly successful. It was a New York Times bestseller, sold millions of copies, and is still wildly popular today. In this book, he claims that the optimal diet for any one individual depends on the person’s ABO blood type. He claims that each blood type represents genetic traits of our ancestors, including which diet they evolved to thrive on.

His Philosophy on how each blood type is supposed to eat:

Type A: Called the agrarian, or cultivator. People who are type A should eat a diet rich in plants, and completely free of “toxic” red meat. This closely resembles a vegetarian diet.

Type B: Called the nomad. These people can eat plants and most meats (except chicken and pork), and can also eat some dairy. However, they should avoid wheat, corn, lentils, tomatoes and a few other foods.

Type AB: Called the enigma. Described as a mix between types A and B. Foods to eat include seafood, tofu, dairy, beans and grains. They should avoid kidney beans, corn, beef and chicken.

Type O: Called the hunter. This is a high-protein diet based largely on meat, fish, poultry, certain fruits and vegetables, but limited in grains, legumes and dairy. It closely resembles the paleo diet.

For the record, I think any of these dietary patterns would be an improvement for most people, no matter what their blood type is.

All 4 diets (or “ways of eating”) are mostly based on real, healthy foods, and a huge step up from the standard Western diet of processed junk food. Most people are blood group O and you mean in Ghana can we do away with corn or carbohydrate? So what therefore happened to our forefathers who know nothing about this? That was one important question that came into mind after reviewing his school of thoughts on the diet type group.

The truth is that even if you go on one of these diets and your health improves, it doesn’t necessarily mean that it had anything to do with your blood type.

Maybe the reason for the health benefits is simply that you’re eating healthier food than before. Simple!

The Bottom Line:
The type A diet resembles a vegetarian diet and Vegetarians also have their own problems with issues of diets as they forgo certain foods, but type O is a high-protein diet that resembles the paleo diet. The other two are somewhere in between.

Lectins are a Proposed Link Between Diet and Blood Type

One of the central theories of the blood type diet has to do with proteins called lectins.

Lectins are a diverse family of proteins that can bind sugar molecules.

These substances are considered to be antinutrients and may have negative effects on the lining of the gut. According to the blood type diet theory, there are many lectins in the diet that specifically target different ABO blood types. It is claimed that eating the wrong types of lectins could lead to agglutination (clumping together) of red blood cells. There is actually evidence that a small percentage of lectins in raw, uncooked legumes, can have agglutinating activity specific to a certain blood type. For example, raw lima beans may interact only with the red blood cells in people with blood type A.

Overall, however, it appears that the majority of agglutinating lectins react with all ABO blood types .

In other words, lectins in the diet are NOT blood-type specific, with the exception of a few varieties of raw legumes.

This may not even have any real-world relevance, because most legumes are soaked and/or cooked before consumption, which destroys the harmful lectins. So in conclusion, some foods contain lectins that may cause red blood cells to clump together. Most lectins are not blood type specific.

Is There Any Scientific Evidence Behind The Blood Type Diet?

Research on ABO blood types has advanced rapidly in the past few years and decades.

There is now strong evidence that people with certain blood types can have a higher or lower risk of some diseases. For example, type Os have a lower risk of heart disease, but a higher risk of stomach ulcers.. However, there are no studies showing this to have anything to do with diet.

The Studies.
In a large observational study of 1,455 young adults, eating a type A diet (lots of fruits and vegetables) was associated with better health markers. But this effect was seen in everyone following the type A diet, not just individuals with type A blood.

Dr. Peter D’Adamo’s book Eat Right for Your Type makes the astounding claim that people with different blood types should eat different foods. Type O’s, for example, is supposed to be like the hunter and eat a lot of meat, whereas type A’s are supposed to eat less. A 2013 systematic review of the evidence supporting blood type diets was published in one of the world’s most prestigious nutrition journals. The researchers didn’t find any.

The researchers sifted through over a thousand papers that might shed some light on the issue, and none of the studies showed an association between blood type diets and health-related outcomes. They conclude that “there is currently no evidence that an adherence to blood type diets will provide health benefits, despite the substantial presence and perseverance of blood type diets within the health industry.”

Ten years earlier, the Journal of the Norwegian Medical Association released a number of papers that came out of a day-long scientific seminar held by the Norwegian Society for Nutrition. 40,000 copies of the Eat Right for Your Type had been sold in Norway, and so the researchers sought to determine whether blood type diets were visionary science or nonsense. They also concluded that they are nonsense.

The author of the blood type diet book responded to the review on his website, saying that “there is good science behind the blood type diet, just like there was good science behind Einstein’s mathematical calculations.” He says that if blood type diets were just tested in the right way, like Einstein’s E=MC2, he would be vindicated. The reason we don’t see any studies on blood types and nutrition, he complains, is “because of little interest and available money.” But he’s sold more than seven million books. Why doesn’t he fund his own studies? That’s what the Atkins Corporation did.

In fact, he has! In 1996, he wrote, “I am beginning the eighth year of a ten year trial on reproductive cancers, using the Blood Type Diets … By the time I release the results in another 2 years, I expect to make it scientifically demonstrable that the Blood Type Diet plays a role in cancer remission.” OK, so that would be 1998. The results? Still not released, sixteen years later.

Good tactic, though, saying you’re just about to publish a study and banking that nobody would actually follow up. So in his sequel, he said he was currently conducting a “twelve-week randomized, double-blind, controlled trial implementing the Blood Type Diet, to determine its effects on the outcomes of patients with rheumatoid arthritis.” That was ten years ago.

The Norwegian colleague bemoaned, “It is difficult not to perceive the whole thing as a crass fraud.”

Researchers from the University of Toronto (U of T) have found that the theory behind the popular blood type diet–which claims an individual’s nutritional needs vary by blood type–is not valid. The findings are published in PLoS One.

“Based on the data of 1,455 study participants, we found no evidence to support the ‘blood-type’ diet theory,” said the senior author of the study, Dr. Ahmed El-Sohemy, Associate Professor and Canada Research Chair in Nutrigenomics at the U of T.

“The way an individual responds to any one of these diets has absolutely nothing to do with their blood type and has everything to do with their ability to stick to a sensible vegetarian or low-carbohydrate diet,” said El-Sohemy.

Researchers found that the associations they observed between each of the four blood-type (A, B, AB, O) diets and the markers of health are independent of the person’s blood type.

The U of T researchers took an existing population of mostly young and healthy adults who provided detailed information about their usual diets and provided fasting blood that was used to isolate DNA to determine their ABO blood type and the level of cardiometabolic risk factors, such as insulin, cholesterol, and triglycerides. Diet scores were calculated based on the food items listed in Eat Right for Your Type to determine relative adherence to each of the four ‘blood-type’ diets.

El-Sohemy says that a previous lack of scientific evidence doesn’t mean the diets didn’t work. “There was just no evidence, one way or the other. It was an intriguing hypothesis so we felt we should put it to the test. We can now be confident in saying that the blood type diet hypothesis is false.” Last year, a comprehensive review published in the American Journal of Clinical Nutrition found no evidence to support the ‘blood-type’ diet and called for properly designed scientific studies to address it.

Take-Home Message
So in conclusion, I do not pretend that many people have experienced positive results by following the diet. However, what I mean is that this does NOT mean that this was in any way related to their blood type.

Different diets work for different people. Some people do well with a lot of plants and little meat (like the type A diet), while others thrive eating plenty of high-protein animal foods (like the type O diet). In case you got great results on the blood type diet, then perhaps you simply found a diet that happens to be appropriate for your metabolism and this is what I will be writing on-personalized testing. It may not have had anything to do with your blood type. It may be the fact that you have found your unique diet plan or what is good for you or not good for you .Also; this diet removes the majority of unhealthy processed foods from people’s diets. Perhaps that is the single biggest reason that it works, without any regard to the different blood types.

That being said, if you are on the blood type diet and it works for you, then by all means keep doing it and don’t let this article dishearten you. If your current diet ain’t broken, don’t fix it.

From a scientific standpoint, however, the amount of evidence supporting the blood type diet is particularly underwhelming.. the simple truth is that there is no science supporting this.

The Blood Type Diet: An Evidence-Based Review – Healthline

To be accessed at

Michael Gregor. Blood Type Diet Perceived as “Crass Fraud”

To be accessed at › Dr. Greger’s Medical Nutrition Blog

Jingzhou Wang, Bibiana García-Bailo, Daiva E. Nielsen, Ahmed El-Sohemy(2014). ABO Genotype, ‘Blood-Type’ Diet and Cardiometabolic Risk Factors. PLoS ONE; 9 (1): e84749 DOI: 10.1371/journal.pone.0084749

Raphael Nyarkotey Obu, PhD

Raphael Nyarkotey Obu, PhD, © 2017

Prof Raphael Nyarkotey Obu is an honorary professor of holistic medicine-Vinnytsia State Pedagogical University, Ukraine and the President of Nyarkotey College of Holistic Medicine, Tema Community 7, Post office.Column: RaphaelNyarkoteyObu

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