In November the local ADSA branch hosted a book club brunch continuous education event. A colleague and I did a review of the popular diet book Eating Right for Your Blood Type, written by Dr. Peter J. D’Adamo, a naturopathic physician. The book was initially published in 1996, almost 20 years on it is a best seller which continues to sell well on Amazon and other retails outlets.
When I worked in corporate wellness, part of my job was to answer ask the dietitian email queries. Not surprisingly weight loss was the most popular category of question, what did surprise me was how common questions on blood type diets were. I have read reviews of the book and diet, read studies reviewing the evidence and reviewed blood type eating plans in the past, but had not read the Eat Right For Your Type book cover to cover before, this was a great opportunity to do so. In essence: I totally agree with D’Adamo that a one-size-fits-all approach to diet does not work, my concern with this is that I don’t believe that the four-sizes offered by the four blood types can adequately fit-all either.
Here is a summary of our review:
Blood Group Diet Theory
D’Adamo explains that blood types have evolved through evolution of man. According to D’Adamo, protein components in food (called lectins) bind with antigens on blood cells and lead to blood cell clumping, or agglutination. Avoiding agglutination, believes D’Adamo, can improve health by helping people manage weight better and fight cancer and heart disease.
If you follow your blood type plan regime carefully, you can:
- Avoid many common viruses and infections.
- Lose weight, as you body rids itself of toxins and fats.
- Fight back against life-threatening diseases, such as cancer, cardiovascular disease, diabetes, and liver failure.
- Avoid many of the factors that cause rapid cell deterioration, thus slowing down the aging process.
Type O: belong to the oldest genetic group and need to eat meat virtually every day to satisfy ancient, hunter-gatherer genes. Type O’s should also avoid oats, wheat, and most grains, because they are all products of an agriculture that didn’t exist when O’s originated.
Type A: evolved after the start of agrarian society and are best off as a vegetarian.
Type B: emerged as humans migrated toward colder, harsher climates. Bs’ can have the most varied diet, including meat, and theirs is the only blood type that does well with dairy products.
Type AB: is a relatively modern adaptation that arose from the intermingling of the A’s and the B’s. Therefore, AB’s have the benefits and intolerances of types A and B.
- Many see health improvements and/or weight loss based on positive improvements made to their diet and lifestyle.
- There is a focus on home cooked meals and avoidance processed food and simple carbs.
- he plan encourages exercise.
- No evidence currently exists to validate the proposed health benefits of blood type diets.1
- Observational studies have demonstrated there are links between ABO blood types and an increased risk of certain diseases. However, a systematic search of the literature found a lack of evidence that blood type diets result in better health outcomes and a reduced risk of developing diseases associated with the blood types.1
- Restriction can lead to boredom, a common drawback of ‘diets’ – making the plan difficult to sustain.
- May experience nutritional deficiencies (supplements are recommended).
- Places to much emphasis on blood type and fails to take into account individual differences – preferences, health challenges…
- Complicated if members of the family/household have different blood types.
The Bottom Line
A 2013 systematic review completed by Cusack and colleagues, published in the American Journal of Clinical Nutrition, found that despite the popularity of the blood type diet, the evidence-based literature does not substantiate these claims. The health claims are only theoretical and not supported by high quality research.