Popular blood type diet debunked

Researchers from the University of Toronto U of T paleo cereal alternative have found that the theory behind the popular blood type diet which claims an individual's nutritional needs vary by blood type is not valid. The findings are published this week in PLoS One.

Researchers found that the associations they observed between each of the four blood-type A, B, AB, O diets and the markers of health are independent of the person's blood type.

The theory behind the diet is that the ABO blood type should match the dietary habits of our ancestors and people with different blood types process food differently. According to the theory, individuals adhering to a diet specific to one's blood type can improve health and decrease risk of chronic illness such as cardiovascular disease. The book was a New York Times best-seller that has been translated into 52 languages and sold over 7 million copies.

The U of T researchers took an existing population of mostly young and healthy adults who provided detailed information about their usual diets and provided fasting blood that was used to isolate DNA to determine their ABO blood type and the level of cardiometabolic risk factors, such as insulin, cholesterol and triglycerides. Diet scores were calculated based on the food items listed in Eat Right for Your Type to determine relative adherence to each of the four 'blood-type' diets.

El-Sohemy says that a previous lack of scientific evidence doesn't mean the diets didn't work. It was an intriguing hypothesis so we felt we should put it to the test. We can now be confident in saying that the blood type diet hypothesis is false." Last year, a comprehensive review published in the American Journal of Clinical Nutrition found no evidence to support the 'blood-type' diet and called for properly designed scientific studies to address it.