Blood-type diet debunked again

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297479_6204In 1996 naturopathic physician - whatever that means - Peter D Adamo published his Eat Right for Your Type diet book, claiming that people with different blood types should eat differently to preserve health and lose weight. The diet is based on the theory that different human blood types evolved at different times in our history, and therefore, we should be eating foods that were available to people at the period when each type first made its appearance.

For example, a person with type B blood should be eating foods high in dairy products because supposedly that type first occurred when humans left a nomadic way of life and started domesticating cattle and such animals, and using their milk. It s an intriguing theory, but it s just that a theory, as noted by Drs. Elizabeth Whelan and Fredrick J. Stare in their 1998 book, Fad-Free Nutrition. But in the last 17 years, there have been no scientific studies validating this theory.

Indeed, last year, Dr. Leila Cusack from the Belgian Red Cross and colleagues reviewed over 1400 articles from the scientific literature to see if they could find any that validated the theory that adherence to a such a specific diet could improve health or decrease the risk of disease. Out of all those articles, they found only one that came close, and it examined the effect of a different blood type grouping diet.

More recently, Dr. Jingzhou Wang of the University of Toronto and colleagues had over 1400 participants young adults between 20 and 29 years old fill out a food frequency questionnaire for a month s worth of food intake. Each person was assigned a diet that, according to the blood type theory, should have decreased their cardiometabolic risk factors.In their discussion the authors noted Our findings show that adherence to certain Blood-Type diets is associated with a favorable profile for certain cardiometabolic risk factors in young adults, but these associations were not related to an individual's ABO blood group.

ACSH s Dr. Ruth Kava commented It s no surprise that there are no data supporting D Adamo s theory of the blood-type diet having a particularly beneficial effect. As the Canadian researchers found, when people adhered to a prudent diet, no matter what their blood type, they improved their cardiometabolic risk factors. Just one more bizarre diet theory debunked the only surprising thing here is that it took so long to happen!