The ‘Blood Type Diet’ by Peter D’Adamo ND has been a popular diet choice in the natural health community for several decades. It continues to be a popular method in the complementary health field, but its use lacks robust evidence.
While there are correlations between ABO blood-type and some disorders such as carcinomas (1), and between blood type and personality traits (2) these and other findings would be considered quite preliminary and speak little to the veracity of claims for a link between diet, blood type and health outcomes.
However, very little research has subsequently been performed in the area of blood-type diets. area. A literature search for the ‘Blood Type Diet’ revealed only one substantial study performed on the diet and markers of health. In this study, 1,455 people were assessed over one-month for the effect of the blood-type diet on cardiometabolic markers. Differences were observed in response to the diets. For example, the Type-A diet in this study was related to lower BMI, waist circumference, blood pressure, serum cholesterol, triglycerides, insulin, HOMA-IR and HOMA-Beta (P<0.05). Adherence to the Type-AB diet was also associated with lower levels of these biomarkers (P<0.05), except for BMI and waist circumference. Moreover, adherence to the Type-O diet was associated with lower triglycerides (P<0.0001). However, there was no observed effect 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.” (4)
It is likely that people who achieve good results following a blood-type diet have coincidentally happened upon a diet that excludes foods that they are intolerant or allergic to. Similarly some of the diets may allow them to restrict calories or alter macronutrients (for example, increasing protein) more easily, and this may facilitate weight-loss or cardiometabolic outcomes. And as with many diets, the act of being on a ‘diet’ can encourage people to be more mindful of the foods they eat and / or limit their compendium of foods to ones that are more health-promoting. It is unlikely that blood type however plays any role in these outcomes.
In conclusion,, we agree with a 2013 systematic review of the available evidence which stated that “no evidence currently exists to validate the purported health benefits of blood type diets” (5).
1.Su, M., Lu, S. M., Tian, D. P., Zhao, H., Li, X. Y., Li, D. R., & Zheng, Z. C. (2001). Relationship between ABO blood groups and carcinoma of esophagus and cardia in Chaoshan inhabitants of China. World journal of gastroenterology, 7(5), 657-661.
2. Tsuchimine, S., Saruwatari, J., Kaneda, A., & Yasui-Furukori, N. (2015). ABO Blood Type and Personality Traits in Healthy Japanese Subjects. PLoS ONE, 10(5), e0126983. doi:10.1371/journal.pone.0126983
3. Meltzer, H. M., Haugen, M., Haavardsholm, K. C., Hagen, K. B., Heier, H. E., McKellep, A. M., . . . Tandberg, A. (2002). [Blood type diet--visionary science or nonsense?]. Tidsskr Nor Laegeforen, 122(14), 1402-1405.
4. Wang, J., García-Bailo, B., Nielsen, D. E., & El-Sohemy, A. (2014). <italic>ABO</italic> Genotype, ?Blood-Type? Diet and Cardiometabolic Risk Factors. PLoS ONE, 9(1), e84749. doi:10.1371/journal.pone.0084749
5. Cusack, L., De Buck, E., Compernolle, V., & Vandekerckhove, P. (2013). 23W2E3 The American journal of clinical nutrition, 98(1), 99-104. doi:10.3945/ajcn.113.058693