Does the Blood-Type Diet Work?

The most effective diets are those that are designed to take into account the people who are using them. Dieting is not a problem with a ‘one-size-fits-all’ solution, but rather it’s a challenge that requires specific treatment in each case. The right diet will be based on your metabolism, on your likes and dislikes, on your fitness regime and on your daily schedule among other factors.

But one thing that your diet certainly doesn’t need to be based on is your blood type. Why? Because blood type has absolutely no bearing on what you eat and anyone who claims otherwise is either misguided or trying to get you to pay for an expensive book or other product.

Where Does the Blood-Type Diet Come From?

The blood-type diet was originally conceived by one Peter J. D’Adamo who wrote the book ‘Eat Right 4 Your Type’. He claims throughout that book and his subsequent cash-ins, sorry sequels, that his research was based on and backed by the work of biochemists and glycobiologists. Only if you ask any dietician, physician or scientist they will tell you that that’s completely not the case. There is no existing research or theory to back D’Adamo’s claims and it appears as though his dietary recommendations are completely arbitrary.

The reasoning that D’Adamo gives is that the blood type interacts with lectins in our food – carbohydrate binding proteins that are specific to different functional groups. He goes on to claim that this should then dictate your diet based on primary blood type O, A, B or AB.

D’Adamo uses the evolutionary theory of blood type groups of William C. Boyd. In his book ‘Genetics and the Races of Man’, Boyd described how genetic analysis of blood groups could be used to categorise alleles and thus genetic heritage. He grouped the population into 13 geographical ‘species’ based on the distribution of particular blood-group genes.

D’Adamo then uses this as the basis of his dietary recommendations – stating that differences in heritage and evolutionary history as indicated by blood type should dictate different dietary requirements.

Blood Types and Diets According to D’Adamo

Those who follow the blood-type diet will then find out their own blood type and follow the recommendations below:

Type O: The blood-type diet describes blood group O as ‘the hunters’ and states that they were the first blood group to emerge and that they should thus eat a higher protein diet.

Type A: The diet describes group A as ‘the cultivators’ and states that they emerged around the early dawn of agriculture. It recommends that those with blood type A should eat diets high in vegetables and should avoid red meats.

Type B: ‘The Nomad’. According to the blood-type diet, type B’s date back around 10,000 years ago and have a strong immune system and flexible digestive system. It concludes that those with blood type B should seek out dairy products (whereas others should avoid them) and can enjoy a much broader diet.

Type AB: D’Adamo describes AB blood type as ‘the enigma’ and suggests it to be the most recent blood group only dating back 1,000 years. He states that type AB individuals should eat a diet somewhere between that of type A and type B.

How Do We Know It’s Wrong?

Reading all this you may be forgiven for thinking that it sounds fairly sound and based in science. In reality though, the diet is simply designed to sound scientific when it actually completely misinterprets the information it cites and draws some rather erroneous conclusions without any evidence or even reasoning to back up those claims.

Take for instance the suggestion that type B’s are the ‘only blood type to thrive on dairy products’. In reality, type B blood types are the most likely to come from Asia, South America or Africa where lactose intolerance is most common.

Likewise, D’Adamo asserts that blood group O is the ‘oldest’ – again based on no evidence whatsoever – when research heavily suggests that type A is actually the oldest.

D’Adamo faintly tries to back up his theories by pointing to the effects of lectins on blood type. In fact there is no scientific evidence that lectins should react differently with different blood types. More to the point, even if there was a connection between diet, lectins and wellbeing, D’Adamo provides no rational as to why he chooses the foods he does for the different blood types.

Studies have conclusively demonstrated that the blood-type diet doesn’t work and there genuinely isn’t a single peer-reviewed study demonstrating anything different. It appears that the blood-type diet was conjured completely from the imagination of D’Adamo without rhyme or reason and certainly isn’t worth your time or money. It’s for this reason that the scientific community has damningly labelled the blood-type diet as ‘blood astrology’. Steer clear!

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