Does the Blood Type Diet Really Work?

Written by Dr. Steve Chaney on . Posted in Food and Health, Issues

Is Eating Right For Your Blood Type A Sham?

Author: Dr. Stephen Chaney

cb43e76f-6bf7-4e82-8fc1-95005d2c5626Does the Blood Type Diet really work? In 1997 Dr. Peter J. D’Adamo wrote a book about the blood type diet called “Eat Right 4 Your Type”. Dr. D’Adamo claims that people with different blood types process food differently, so their blood type determines the type of diet that is healthiest for them. Specifically, he claims that people with:

  • Blood group O are descended from hunters and should consume high protein diets.
  • Blood group A are descended from farmers and should consume a near vegetarian diet – completely avoiding red meats.
  • Blood group B are descended from nomads. They have the most flexible digestive system and can eat the widest variety of foods – even dairy products, which he does not recommend for any of the other blood types.
  • Blood group AB are an enigma and are somewhere between blood group A and blood group B.

It’s an interesting concept. Dietary recommendations are made for populations as a whole, and there is tremendous genetic variation in populations. Because of that genetic variation, there is no perfect diet for everyone. Every knowledgeable health expert will tell you that.

The question then becomes “How do you know what kind of diet is healthiest for you?”

The blood type diet is a very simple system. Your blood type is easy to determine. Once you know your blood type you know what to eat. There’s no guesswork.

Could it really be so simple? Over 7 million copies of Dr. D’Adamo’s book have been sold. Millions of people believe in this concept. So it is only fitting to ask “What is the evidence?”

An Objective Scientific Analysis of the Blood Type Diet

There is no doubt that blood type is related to some human genetic and physical traits, but the important question is whether blood type is related to the health outcomes of different diets – the central thesis of Dr. D’Adamo’s book. A Belgian group lead by Dr. Emmey De Buch did a systematic search of the scientific literature to answer that very question (L. Cusack et al, Am J. Clin. Nutr. , 98: 99-104, 2013).

They identified 1415 scientific articles that had the phrase “blood type diet” in either the title or abstract. Then they begin the elimination process. They eliminated:

  • Studies done in test tubes, cell culture, or animals. Only human clinical studies were included.
  • Reviews, commentaries, letters or opinions. Those contained no original scientific research.

At this point they were down to just 16 published clinical studies. Then they asked which of those studies were designed to test the central hypothesis of the blood type diet. They asked:

  • Did the study start with human subjects grouped according to blood type?
  • Did the study have an intervention in which the subjects were required to adhere to a particular type of diet?
  • Did the study measure a health outcome of the dietary intervention?

Guess what? Only one study met these criteria. Just one! And it was a fairly weak study involving a totally different blood typing system than the ABO blood groups.

The Bottom Line:

1)     There is no scientific evidence supporting the blood group diet. A lot has been written about the diet, but nobody has actually shown that it works. The Emperor Has No Clothes!

These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure or prevent any disease.

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Comments (4)

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    I’m really impressed with your writing skills and also with the layout in your blog.
    Is this a paid subject or did you customize it your self?
    Anyway stay up the excellent quality writing, it’s rare to see a great weblog like this
    one these days..

    Reply

    • Dr. Steve Chaney

      |

      Dear Tiffany,
      Thanks for your comments. I definitely had help setting up the blog. I’m a scientist, not a tech expert.
      Dr. Chaney

      Reply

  • Nancy Fickas

    |

    You have done a fantastic job clarifying for us so much misleading information this is out in the news and on the web. Kept it coming I love to be able to have a source for accurate information. Nancy

    Reply

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Latest Article

Is There Hope for Alzheimer’s

Posted August 26, 2014 by Dr. Steve Chaney

Preventing Cognitive Decline As We Age

Author: Dr. Stephen Chaney

 alzheimer's

As we age nothing is more terrifying than the word Alzheimer’s. For most of us the ultimate irony would be to spend a lifetime taking good care of our body, only to lose our mind. From time to time there are encouraging reports about the potential of low fat diets, diets rich in fruits and vegetables, B vitamins, omega-3 fatty acids, various herbs, and other natural approaches that might slow cognitive decline as we age.

Inevitably, it seems, those hopes are dashed by subsequent meta-analyses supposedly showing that each of those approaches is worthless. That wouldn’t be so bad if there were effective medications to slow cognitive decline and prevent Alzheimer’s, but there aren’t. The Alzheimer’s drugs on the market today simply have not been shown to be effective.

But, what if all of these studies were missing the mark by focusing on individual interventions? Perhaps we should be focusing a holistic approach instead.

 

The Power of Holistic Approaches

One of the examples of the power of a holistic approach that I love to use, because it really made an impression on me as a young scientist, occurred at an International Cancer Symposium I attended more than 30 years ago.

I attended a session in which an internally renowned expert was giving his talk on colon cancer. He said, “I can show you, unequivocally, that colon cancer risk is significantly decreased by a lifestyle that includes a high-fiber diet, a low-fat diet, adequate calcium, adequate B-vitamins, exercise and weight control. But I can’t show you that any one of them, by themselves, is effective.”

The question that came to me as I heard him speak was: “What’s the message that a responsible scientist or responsible health professional should be giving to their patients or the people that they’re advising?” You’ve heard experts saying: “Don’t worry about the fat” “Don’t worry about calcium.” “Don’t worry about B-vitamins.” “Don’t worry about fiber.” “None of them can be shown to decrease the risk of colon cancer.”

Is that the message that we should be giving people? Or should we really be saying what that doctor said many years ago – a lifestyle that includes all of those things significantly decreases the risk of colon cancer?

What about Alzheimer’s and cognitive decline? Could a holistic approach have an impact here as well?

 

Is There Hope For Alzheimer’s?

preventing-cognitive-declineA study performed by Dr. Miia Kivipelto and colleagues at the Karolinska Insitute in Sweden and the National Institute for Health and Welfare in Helsinki, Finland suggests that a holistic approach may, in fact, be able to slow cognitive decline in older people.

Previous studies had suggested that exercise, a good diet, socialization and memory training might slow cognitive decline in the elderly, but, like all other individual interventions, the benefits of these interventions were not reproducible. Dr. Kivipelto and colleagues designed a clinical study that combined all of these interventions into a single holistic approach.

They started with 1,260 healthy adults aged 60-77 from Sweden and Finland and divided them into two groups. One group was enrolled in a holistic program involving exercise, a healthy diet, socialization and memory training. This group was closely monitored for compliance. The other group was just given general health advice – not unlike the advice you might expect to receive from your doctor.

Each group was given a memory test at the beginning of the study and a second memory test two years later. Both groups scored about the same on the first memory test. However, the group enrolled in the holistic program did considerably better on the second memory test than the control group who had just been given general health advice.

One of the lead investigators was quoted as saying: “These findings show that prevention is possible, and it may be good to start early [before the signs of cognitive decline become evident]. With so many negative trials of Alzheimer’s drugs reportedly lately, it’s good that we may have something that everyone can do now to lower their risk [of cognitive decline].”

 

Limitations of the Study

There are two big caveats for this study.

1)     The study was too short to assess the effectiveness of this approach at reducing Alzheimer’s. The investigators plan to continue the study for 7 years. They hope that enough participants will have developed Alzheimer’s by then so they can accurately assess whether this approach is as effective at preventing Alzheimer’s as it is at preventing cognitive decline.

2)     This study was recently presented at an Alzheimer’s Association International Conference. It has not yet undergone the rigorous peer review required for publication. Once the study has been published I will give you an update.

 

The Bottom Line

1)     It has been very difficult to prove that individual interventions, whether they are natural or pharmaceutical, are effective at preventing cognitive decline and the onset of Alzheimer’s as we age.

2)    However, a recent study suggests that a holistic approach that includes exercise, optimal nutrition, socialization and memory training may be effective at preventing cognitive decline in older adults.

3)     Based on previously published individual studies, optimal nutrition probably includes:

  • A diet low in fat, especially saturated fat and trans fats
  • A diet with lots of fresh fruits and vegetables
  • Extra B vitamins, especially with high risk populations
  • Extra omega-3 fatty acids

4)     Although not mentioned in this study, maintaining proper body weight is also an important part of a holistic approach to reducing the risk of cognitive decline. In a previous “Health Tips From the Professor” I shared data showing that obesity alone can cause a 3-fold increase in the risk of developing dementia.

5)    The take home message should not be that each of the natural interventions is ineffective at preventing cognitive decline as we age. Rather, the message should be that a holistic approach that combines all of the natural interventions may be effective at preventing cognitive decline.

These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure or prevent any disease.

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