This posting appears to be made by Tom Greenfield (aka “aperson”) who declared ‘No competing interests’. However, a quick search reveals that Tom Greenfield is a naturopath who uses the blood type diet (BTD) and is a regular contributor to Dr. D’Adamo’s blog: http://www.dadamo.com/B2b...
This is a clear conflict of interest that he fails to declare, which violates the competing interests policy clearly stated here.

Tom Greenfield then cites a severely flawed ‘analysis’ by Dr. D’Adamo, the naturopath who wrote the BTD book, where he concludes that our participants adhered to only 13.7% of the BTD. This figure is based on 74 foods being captured by our food frequency questionnaire from a total of 540 foods listed in the BTD (74/540 x 100% = 13.7%). But, a closer examination of those 540 foods reveals that almost 80% of them (426) are considered neutral for at least one of the blood type diets, which according to the BTD book means it does not matter if a person consumes them or avoids them. Including such a large number of neutral foods in the denominator only serves to grossly inflate the number of foods that were not captured by our food frequency questionnaire and is highly misleading. Surely both of these naturopaths (Greenfield and D’Adamo) should know this. Putting aside those hundreds of irrelevant foods that have no impact on the blood type diet scores, if we look at the foods that are described as beneficial or should be avoided in Eat Right 4 Your Type we find a list of many exotic and unusual foods (eg frogs, turtles, squirrels, etc…) that our population does not consume. As we described in our paper, our scoring system provided a good estimate of adherence to the blood type diets and any effects that were observed had nothing to do with an individual’s blood type, thereby demonstrating that the theory is false.

Finally, Tom Greenfield calls upon a “properly conducted study which fully understands the scientific basis on which the blood type diet is based” to be conducted. What scientific basis is that? Even Dr. D’Adamo now admits there is no scientific evidence to support the blood type diet (BTD) and states the following on his blog: “That the BTD theory is currently unproven by rigorous scientific study is not argued” – Peter D’Adamo: http://n-equals-one.com/b...

In summary, our study is the first to test the blood type diet hypothesis and the findings clearly show that any effects have nothing to do with a person’s blood type.