The blood type diet, also known as the blood group diet, was popularized by naturopathic doctor Peter D’Adamo back in 1996.
His book, Eat Right 4 Your Type, was a New York Times bestseller, has sold over 7 million copies, and is still popular today.
In this book, he claims that the optimal diet for any one individual depends on the person’s ABO blood type. That is, whether your blood type is Type A, B, AB or O.
It's an interesting theory, and there is strong evidence that people with certain blood types can have a higher or lower risk of some diseases.
However, there are no studies showing this has anything to do with diet. In fact, the only study to test this theory has shown it to be false.
In this study, researchers looked at almost 1,500 subjects on each of the four blood type diets, and documented several outcomes like waist circumference, blood pressure and insulin levels.
They found that adherence to either the A,B or O type diets was associated with some beneficial effects. Not surprising of course, as most diets tend to work in the beginning when people first begin to eat fewer calories overall, or avoid the worst indulgences. Plus each of the dietary patterns are healthy and would be a huge improvement for most people.
However, the big finding was that, the beneficial effects had nothing to do with an individual’s blood type. If a person followed the type A diet, they would see similar health effects regardless of whether they had A, B, AB or O type blood.
This just shows the dietary patterns are healthy, which explains why so many people swear that it works. But it would work equally well on someone with an ‘incompatible’ blood type.
So the main conclusion of the study was actually that although the eating patterns themselves are healthy, it has absolutely nothing to do with a person’s blood type.
Senior author Ahmed El-Sohemy, even said: "We can now be confident in saying that the blood type diet hypothesis is false".
Now the study was not perfect, and in research you can always find some flaw or weakness to point to if you disagree with the results. But given the lack of plausibility, this large study is sufficient to reject the blood type theory.
The burden of proof now falls on D'Adamo to show us otherwise- to show that is does indeed work, much like The Atkins corporation did.
And with over 7 million copies of the book sold, and millions of dollars since spent on developing and marketing related cookbooks, supplements, and even apps and software, it's very strange that his company have not yet invested in any good research to prove their own theory.
Further reading: https://authoritynutrition.com/the-blood-type-diet-review/
Follow Authority Nutrition:
Google Plus: https://plus.google.com/+Authoritynutrition/posts
---- Don't forget to subscribe on YouTube here: https://www.youtube.com/user/AuthorityNutrition?sub_confirmation=1
Study mentioned in video:
Study 1: http://www.ncbi.nlm.nih.gov/pubmed/24454746