Blood Type Diet Doctor Shoots Back Citing Flaws and Possible Conflict of Interest

Jan 21, 2014, 12:53 ET from D'Adamo Personalized Nutrition

WILTON, Conn., Jan. 21, 2014 /PRNewswire/ -- Dr. Peter D'Adamo, creator of the popular Blood Type Diet, fires back at recent study "debunking" his theory.  After reviewing the study, D'Adamo finds that participants weren't following his program and that the lead researcher on the study has an ownership stake in a rival company.

A newly published study out of the University of Toronto looking at the effects of the Blood Type Diet, popularized by Dr. Peter J. D'Adamo's internationally best-selling book, Eat Right For Your Type, claims that they have 'effectively debunked' his blood type dietary theory. 

But not so fast.

Survey data suggests that the participants weren't even following the Blood Type Diet, and, according to a disclaimer on the site, one of the lead investigators, Ahmed El-Sohemy, is the founder of Nutrigenomix, a company that markets nutrigenomic test kits and customized dietary reports to dietitians rivaling those of Dr. D'Adamo.

The study, published January 15, in PLOS Medicine is part of the Toronto Nutrigenomics and Health study. The study's subjects simply kept diet diaries and a 'diet score' was calculated to determine their adherence to the respective diet for their blood type. Based on the food items listed in the Blood Type Diet, subjects received one positive point for consuming one of each food from the recommended lists, and one negative point listed for each of the foods consumed on D'Adamo's "avoid" list.

Unfortunately, this is a gross simplification of Dr. D'Adamo's work. For example, a blood type A subject (the type D'Adamo recommends to be a vegetarian) eating 12 ounces of high-fat hamburger three times per week would have a 'zero′ rating if they garnished the hamburger with onions. Simply giving +1 and -1 values for following or not following the food choices will most likely result in the subject's results simply marching backwards and forwards and often just canceling out.

The study also misclassifies numerous foods or lumps them into impossible-to-categorize groups that are not part of the Blood Type Diet. For example, 'Mac and Cheese' is listed as neutral for types A, B and AB. However, 'mac and cheese' is almost universally made with processed American cheese, which is listed as an avoid for those types.  Further, the study design resulted in almost the entire population being in high compliance with the AB diet, which is applicable to about 2% of the population.  This further undermines the study's flawed structure and ability to evaluate the impact of the Blood Type Diets for each blood type. 

Interestingly, given its short length, the study's authors themselves admit that the diets produced positive effects in those that showed relatively high adherence to the Type A, Type AB, and Type O diets, reporting weight loss and favorable levels of cardo-metabolic disease risk factors.

Dr. Todd LePine, a medical doctor who has recommended that his own patients follow their Blood Type Diet, says, "From this study you can't conclude anything, except that the Blood Type Diet was beneficial in all cases. But in this limited time frame and relatively unscientific study, we don't have the power or time frame to conclude much of anything." 

Further complicating the results is the relationship between Dr. El-Sohemy and Nutrigenomix where he is a shareholder. Nutrigenomix, a University of Toronto spin-off biotechnology company spearheaded by Dr. Ahmed El-Sohemy, provides genetic testing and dietary programs similar to Dr. D'Adamo's.

Dr. D'Adamo had this to say about the study: "This study had the opportunity to shed new light on complex topics in nutrigenomics. However its definition of what actually constitutes The Blood Type Diet was simplistic to the point of uselessness.  In addition, the length of the study was too short, and the significance of its negative results over-extrapolated.  Far from proving the ineffectiveness of the Blood Type Diet, it simply demonstrates the previously known fact that in the short term, there are a multitude of approaches to eating healthy – if you are an already healthy young person."

Dr. D'Adamo's full response to the study, and comments from other experts in the field, can be read here.

Dr. Peter D'Adamo's first book, Eat Right for Your Type, is a New York Times Bestseller, with over seven million copies in circulation. The book has been translated into 65 languages.

Ann Quasarano




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