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Blood Type Diets… Still Crazy After All These Years…

Over 7 million copies of Eat Right for Your Type have been sold and many people follow a 'blood type diet'. But does it stand up to scientific scrutiny?
A hospital corpsman with the Blood Donor Team from Naval Medical Center Portsmouth takes samples of blood from a donor for testing

Your blood type is often promoted as a way to determine food choices based on (unproven) allergic responses to lectins in foods, (1) and while over 7 million copies of the Eat Right for Your Type diet bookhave been sold, the evidence for any effect of diet modification is very thin on the ground!

A literature search for “Blood Type Diet” revealed two substantial study performed on the diet and markers of health. In the first study from 2014, 1,455 people were assessed over one month for the effect of the blood-type diet on cardiometabolic markers. There were no observed effects of blood-type on the effectiveness of, or outcomes from, any particular diet. In other words, the diets themselves had differing effects, but blood-type made no difference. The authors concluded, “Adherence to certain ‘Blood-Type’ diets is associated with favourable effects on some cardiometabolic risk factors, but these associations were independent of an individual’s ABO genotype, so the findings do not support the ‘Blood-Type’ diet hypothesis.” (2)

A 2018 study evaluated the effects of the ER4YT diets on risk factors such as blood pressure, waist circumference, and BMI. After 6 months, those with high adherence to type A and B diets had greater reductions in BMI and waist circumference, and type O adherence also resulted in decreases in BMI and waist circumference. But tellingly, “matching the diets with the corresponding ABO genotype of each individual did not change the effect size of any of these associations either at baseline or at 6 months…” (3)

matching the diets with the corresponding ABO genotype of each individual did not change the effect size of any of these associations either at baseline or at 6 months

A previous, 2013 systematic review of the available evidence had concluded that “no evidence currently exists to validate the purported health benefits of blood type diets.” (4)

What does this mean?

Adherence to any ‘better’ diet than a poor one previously followed will result in positive outcomes, but blood type diets are basically a waste of time.

blood type diets are basically a waste of time.

References

1.            D’Adamo P. Dr. Peter D’Adamo and the Blood Type Diet: Official Site 2016 [Available from: http://www.dadamo.com/.

2.            Wang J, García-Bailo B, Nielsen DE, El-Sohemy A. <italic>ABO</italic> Genotype, ?Blood-Type? Diet and Cardiometabolic Risk Factors. PLoS ONE. 2014;9(1):e84749.

3.            Wang J, Jamnik J, García-Bailo B, Nielsen DE, Jenkins DJ, El-Sohemy A. ABO Genotype Does Not Modify the Association between the “Blood-Type” Diet and Biomarkers of Cardiometabolic Disease in Overweight Adults. The Journal of Nutrition. 2018;148(4):518-25.

4.            Cusack L, De Buck E, Compernolle V, Vandekerckhove P. Blood type diets lack supporting evidence: a systematic review. The American Journal of Clinical Nutrition. 2013;98(1):99-104.

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