The Blood Type Diet: Fact or Fiction?

Amy Barczy

| 4 min read

Amy Barczy is a former brand journalist who authored content at Blue Cross Blue Shield of Michigan. Prior to her time at Blue Cross from 2019-2024, she was a statewide news reporter for She has a decade of storytelling experience in local news media markets including Lansing, Grand Rapids, Holland, Ann Arbor and Port Huron.

Does your blood type determine how your body responds to different foods?
The theory of the Blood Type Diet – first popularized in 1996 by Dr. Peter J. D'Adamo in his book "Eat Right 4 Your Type" – still has loyal followers, yet it remains a highly debated topic among nutrition experts and researchers. Recently, social media users have proliferated this unproven theory.
The Blood Type Diet suggests that an individual's blood type should dictate their dietary choices for optimal health. According to this theory, the foods we consume should be tailored to our blood type, as each blood type responds differently to various food groups; however, there is no scientific evidence to support these claims.

What are the different blood types?

Human blood is classified into four major groups: A, B, AB, and O. These classifications are based on the presence or absence of specific antigens on the surface of red blood cells. Antigens are markers on the outside of a cell that help the body’s immune system identify what the cell is.
  • Blood type A has A antigens
  • Blood type B has B antigens
  • Blood type AB has both A and B antigens
  • Blood type O has neither A nor B antigens
Additionally, blood types can be either Rh-positive or Rh-negative, depending on the presence or absence of the Rh antigen.

What is the theory of the blood type diet?

In his book, Dr. D'Adamo claims individuals with different blood types have evolved from different ancestral groups and, therefore, have distinct dietary needs. For instance, he suggests that people with blood type O should follow a high-protein, meat-based diet, similar to that of early hunter-gatherers. In contrast, those with blood type A are advised to consume a vegetarian or plant-based diet. Blood type B individuals are said to benefit from a varied diet that includes dairy, while blood type AB individuals should focus on a primarily vegetarian diet but with some animal protein.

What does the scientific community think about the Blood Type Diet?

Scientific evidence supporting the Blood Type Diet is scarce and largely inconclusive. Several studies have failed to establish a significant connection between blood type and optimal dietary recommendations. For instance, a review published in the American Journal of Clinical Nutrition in 2013 analyzed 1,415 scientific articles and concluded that there was no robust evidence to support the Blood Type Diet's claims.
Moreover, a comprehensive study published in PLoS One in 2014 examined the association between blood type diets and markers of health, including cardiovascular risk factors and insulin resistance. The researchers found no significant differences in these markers among participants following their recommended blood type diets compared to those who didn't.
Another critical point of contention is the lack of scientific rationale behind the proposed mechanisms of the Blood Type Diet. The idea that blood type determines how our bodies react to specific foods contradicts the fundamental principles of human physiology and digestion.
“Your blood type does not change how your digestive system works; and does not affect how your body breaks down food and absorbs nutrients,” said Dr. Angela Seabright, D.O., a care management physician at Blue Cross Blue Shield of Michigan. “This makes it unlikely that blood type alone would significantly influence your nutritional needs.”

How to choose the right diet for you

Your age, gender, level of physical activity and any underlying health conditions play a significant role in your dietary requirements – and should be the deciding factors in guiding any dietary choices, rather than blood type.
Talk to your health care provider about any nutritional concerns you may have about your current diet to see if any changes or adjustments need to be made. Health experts emphasize the importance of a balanced diet rich in fruits, vegetables, whole grains, lean proteins and healthy fats for overall health and well-being.
While the concept of the Blood Type Diet may have gained popularity, the scientific evidence supporting its claims is lacking. Multiple studies have failed to establish a significant link between blood type and optimal dietary recommendations. As such, individuals should focus on evidence-based nutrition guidelines that consider individual needs rather than relying solely on their blood type for dietary decisions.

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