Theory behind popular blood-type diet debunked

University of Toronto
January 15, 2014

Researchers from the University of Toronto (U of T) 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.

"Based on the data of 1,455 study participants, we found no evidence to support the 'blood-type' diet theory," said the senior author of the study, Dr. Ahmed El-Sohemy, Associate Professor and Canada Research Chair in Nutrigenomics at the U of T.

"The way an individual responds to any one of these diets has absolutely nothing to do with their blood type and has everything to do with their ability to stick to a sensible vegetarian or low-carbohydrate diet," said El-Sohemy.

El-Sohemy says that a previous lack of scientific evidence doesn't mean the diets didn't work. "There was just no evidence, one way or the other. 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.