The Blood Group Diet

Is blood group the best way to determine what your diet should be? WLR's dietitian Juliette Kellow investigates the Blood Type Diet and whether eating right for your blood type can help you lose weight.

The Blood Type Diet under the spotlight

By WLR Dietitian

Juliette Kellow BSc RD

Follow a diet that’s designed specifically for your blood group and you’ll lose weight, feel healthier and lower your risk of many diseases. At least, that’s what Dr Peter D’Adamo, naturopath and creator of the Blood Type Diet claims in his book Eat Right For Your Blood Type. No wonder then, that it’s been a hit with Hollywood stars like Liz Hurley and Courtney Cox-Arquette, as well as closer-to-home celebrities, like Martine McCutcheon.

Martine says she refused to watch herself on TV when she first found fame as Eastenders Tiffany Mitchell, because she was so embarrassed about her weight. Then a dose of glandular fever followed by hepatitis piled on even more pounds. After being introduced to the Blood Type Diet she slimmed to a size 10.

But while Martine might be a fan of the Blood Type Diet, most medical and nutrition experts aren’t, and agree that the theory is complete nonsense.

So what is the theory?

Prepare to be blinded by science! Dr D’Adamo believes our blood group determines how our bodies deal with different nutrients. His theory is based on the idea that each blood group has its own unique antigen marker (a substance that the body recognises as being alien) and this marker reacts badly with certain foods, leading to all sorts of potential health problems. Furthermore, Dr D’Adamo believes that levels of stomach acidity and digestive enzymes are linked with your blood type. Consequently, he says, by following a diet designed specifically for your blood type, your body digests and absorbs food more efficiently, with the result that you lose weight.

But here’s where the theory becomes even more weird and wonderful. Dr D’Adamo believes that because blood types evolved at different times throughout history, we should eat a diet based on the types of foods our ancestors typically ate at the time when our blood type was first recognised!

When did the blood types evolve?

Blood Group O was the first blood type to be identified, although how we know this is anyone’s guess – we’re talking about our hunter-gatherer ancestors who were around in 50,000 B.C! Nevertheless, Dr D’Adamo believes because our type O ancestors survived and thrived on a high-protein, meat-based diet, that’s the type of diet blood group Os should follow in the 21st century.

Next came the emergence of blood type A, sometime around 15,000 B.C! By this time, our ancestors’ hunter-gathering days were over and instead they started to settle into farming-type communities. The creation of blood type A around this time meant our ancestors did well on a vegetarian-based diet. And again, Dr D’Adamo recommends that blood group A’s should today follow a veggie diet.

Blood type B supposedly evolved around 10,000 B.C thanks to our nomadic ancestors. They left their farms and started wandering the land, constantly moving from place to place. Consequently, Dr D'Adamo's theory goes, blood group B’s today can get away with eating a varied diet that consists of most foods including meat, dairy, grains and vegetables.

Finally, came blood type AB, which evolved just 1,000 years ago! Dr D'Adamo thinks this blood type helped our ancestors make the transition to modern times. Meaning that people with blood group AB can eat a mixture of the foods suitable for both blood group A and blood group B.

That gives me a good idea, but can you be more specific about what you can and can’t eat?

Each of the four blood types has a detailed list of foods that should be avoided and those that can be included. Here’s the lowdown…

Blood Group O

This is the most common blood group in the UK. Dr D’Adamo says that our digestive tract retains the memory of ancient times, and so type Os need to eat a typical hunter-gatherer type diet. In other words, type Os should follow a high-protein, low-carb diet with lots of meat and fish but no dairy products, wheat or grains.

If that sounds familiar, it’s because it is – the diet recommended for people with blood type O is simply a variation on many of the typical high-protein, low-carb diets that are currently popular, such as the Atkins diet. Foods you can eat freely include meat, fish and olive oil; foods you can eat in moderation include eggs, nuts, seeds, certain vegetables and fruits; and foods to avoid include dairy products, beans, cereals, bread, pasta and rice. To complement your food intake, Dr D’Adamo recommends lots of vigorous aerobic exercise such as aerobics and running – just like our hunter-gatherer ancestors did!

Blood Group A

This is the second most common blood type in the UK. Again according to Dr D'Adamo, digestive system is apparently very good at remembering that our ancestors had settled, farming lifestyles, which included eating lots of grains and vegetables but little meat. Consequently, blood type A’s should follow a vegetarian diet but still avoid dairy products. This means nuts, seeds, beans, cereals, pasta, rice, fruit and veg are all on the ‘to eat’ list. Meanwhile, calming exercises are thought to be best for blood type A’s such as yoga or golf.

Blood Group B

Only one person in 10 has blood type B – a real shame when you consider this blood group has the least dietary restrictions! As our type B ancestors were able to thrive on all sorts of foods, thanks to all that travelling, very few foods need to be avoided and this is the closest you’ll get to a healthy, balanced diet from Dr D'Adamo. The only foods that need to be avoided are processed foods, although nuts and seeds aren’t recommended and only small amounts of carb-rich foods should be eaten. When it comes to exercise, Dr D’Adamo recommends activities that have mental component, such as hiking, tennis and swimming – clearly our ancestors did a lot of thinking while they were walking!

Blood Group AB

People with this rare blood type should eat a combination of the foods recommended for blood groups A and B. Somewhat confusing when type B allows you to eat most foods, while type A suggests a vegetarian diet! Dr D’Adamo gets around this by suggesting that type ABs follow a veggie diet most of the time with some meat, fish and dairy products occasionally. It’s the same when it comes to exercise too – blood type ABs should combine calming exercises with moderately intense activities.

What do the experts say?

Medical experts universally agree that the theory is nonsense, and say there is absolutely no link between our blood group and the diet we eat. Consequently you won’t find qualified nutritionists or dietitians recommending this diet.

There are also several concerns, namely that the diets recommended for blood groups O and A are considerably limited and cut out major groups of foods.

In the long term, this can result in a poor intake of nutrients needed for good health. Cutting out dairy products, for example, will lead to poor intakes of calcium, which can put you at risk of osteoporosis (brittle bone disease), while avoiding meat can result in low intakes of iron, which can lead to anaemia. This is even more worrying in view of the fact that most people in the UK are blood group O or A.

But will the diet help me lose weight?

Almost certainly, but this is because each of the diets for the four blood types eliminates specific groups of food such as bread and cereals, dairy products or meat and fish. Dr D’Adamo doesn’t give any indication about how much weight you’ll lose, it will depend on how much you restrict your food intake.

Are there any pros?

There are not many positive things to say about this diet, which is clearly based on science fiction rather than science fact. However, as with any diet, it will get you thinking about what you are currently eating, with the result that you may start to make changes to your diet. Added to this, the blood type diet recommends eating fresh, natural foods and so can help you de-junk your diet by cutting out processed foods, takeaways, booze, chocolate and too many cups of coffee – all of which our ancestors missed out on!

And the cons?

There are plenty. On a practical level, you may need a blood test to discover your blood group if you don’t already know it – and this will mean a trip to your local health centre! Mealtimes may also be impossible if everyone in the family wants to follow the diet, but has a different blood group! But most importantly, it’s just another cranky way of getting people to cut calories – and the most worrying thing about this is that while you’ll probably lose weight, it could also affect your health in the long term. Nevertheless, if you’re still adamant about giving it a go, it’s best to follow it for just a short time (one week or less) and use it to kick-start a longer-term, healthy, weight-loss plan.

Juliette’s verdict

I’m really not a fan of this diet. It’s filled with pseudo-science and has the potential to scare people into avoiding many nutritious foods in an effort to lose weight. It’s also worth bearing in mind that although the diet gives the impression that it’s based on sound scientific research this is, in fact, far from the case. Ultimately, the theory is nonsense.

Nevertheless, based on Dr D’Adamo’s theory, I’m looking forward to the evolution of blood type F! People with blood type F will need lots of fast food, takeaways, pizza, sugary snacks, crisps and chocolate to remain in tune with their environment. After all, if the theory is correct, surely that’s what we can expect, based on what many of us now eat in the 21st century!