"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," says Ahmed El-Sohemy. (Credit: Shutterstock)

Blood-type diet doesn’t work, study finds

The theory behind the popular blood-type diet is false, new research shows.

Popularized in Peter D’Adamo’s book Eat Right for Your Type, the theory claims an individual’s nutritional needs vary by blood type.

“Based on the data of 1,455 study participants, we found no evidence to support the ‘blood-type’ diet theory,” says Ahmed El-Sohemy, an associate professor and chair in nutrigenomics at the University of Toronto and senior author of the study published in PLOS ONE.

“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,” says El-Sohemy.

Best-selling book

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 theory behind the diet is that the ABO blood type should match the dietary habits of our ancestors and people with different blood types process food differently.

According to the theory, individuals adhering to a diet specific to one’s blood type can improve health and decrease risk of chronic illness such as cardiovascular disease. The book was a New York Times best-seller that has been translated into 52 languages and sold over 7 million copies.

How the study worked

The 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.

Source: University of Toronto

chat4 Comments


  1. Alex

    Did we really need a study to find out this scientifically-unsupported book was bull?

    Great it’s be debunked, but did anyone buy it?

  2. Taz

    It’s not about temporary fad diets. It’s about establishing healthy sustainable eating habits.


  3. Emmad Kabil

    Is this a joke? If you looked up what a blood type is on Wikipedia (let alone a science class) you could see that this diet is crap. People can be so ignorant. 7 million copies? These authors are con men.

  4. Sarah

    How does this prove the blood type diet is false? I would love proof that it’s not true, but I don’t see it here. There are hundreds of people online who attest to its truth. As for studies, that takes a LOT of money. The pharmaceutical world has the money to perform studies, but the alternative world does not…that’s why they haven’t been done.

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