People looking to eat healthily or lose weight (which is nearly all of us!) may have run across a diet claiming that your blood type should influence what you eat. “Eat Right for Your Type,” by naturopath doctor Peter D’Adamo, has proved extraordinarily popular since it was published in the mid-1990s. It has sold over 7 million copies and been translated into 50 languages.
The popularity makes the diet intriguing. But what is the diet? Does it work? And does it make you any healthier?
What Is the Diet?
D’Adamo believes that people react differently to a substance called lectins, which are on the surface of the foods we eat, depending on their blood type. The reactions can cause inflammation, poor digestion, fatigue and weight gain.
His book outlines a specific diet based on blood type — O, A, B, AB — the same types clinics ask about if you ever try to donate blood.
Type O — A high-protein diet emphasizing lean meat, poultry, fish and vegetables. Bread and grain-based foods, beans and dairy are not emphasized.
Type A — A vegetarian diet emphasizing fruits, vegetables, whole grains and legumes.
Type B — This diet stresses green vegetables, eggs, certain meats and low-fat dairy. Type B’s are encouraged to never eat corn, wheat, buckwheat, lentils, tomatoes, peanuts or sesame seeds.
Type AB blood — Foods emphasized are tofu, seafood, dairy and green vegetables. Type AB’s should not have caffeine, alcohol, or smoked or cured meats.
In addition, each blood type is advised to take certain supplements based on the diseases Dr. D’Adamo believes they are prone to.
Is the Diet Beneficial?
Now that you know what it is, is the diet based on blood type beneficial? Does it make you healthier, or help you lose weight?
To some degree, the diet can be beneficial simply because the recommendations for all blood types stress vegetables, which are healthy foods to eat. Many Americans do not eat enough vegetables, so recommendations to eat more can help their overall health and energy. Restricting caloric intake along with eating vegetables can help people lose weight.
In addition, many of the diets for each blood type have healthy food recommendations, such as fruits, whole grains, meat, dairy and legumes.
However, a diet based on blood type also pays no attention to other dietary needs an individual might have. People with diabetes, for example, need to watch their overall carbohydrate intake each day. Eating a lot of carbs might send their blood sugar to unhealthy levels. A person with Type A blood who also has diabetes is encouraged to eat fruit, grains and legumes on the blood type diet — all foods that might inadvertently send the carbohydrate count for the day soaring.
So the diet has some potential for harm if it causes people to ignore their other health conditions. Anyone looking into it would probably do well to run the idea past their doctor first.
As for specific health benefits, a survey of the scientific literature found no evidence that the blood type diet contributed to health.
Dr. D’Adamo’s book pinpoints some facts about health in the modern world that need attention, such as the rise of obesity. However, it is likely that many factors are causing these trends, and they are not related specifically to blood type.
While many aspects of the blood type diet are healthy, there is also the potential for harm. There is ultimately no evidence that a diet based on blood type will benefit one’s health.