I read the blood type diet years ago. I then read the Genotype Diet, an updated version of that book. In the latter one, naturopathic physician Dr. Peter J. D’Adamo devised a litany of physical measurements to determine what type of diet is best for one’s health in addition to the detailed reasons he outlined supporting his Blood Type Diet book published years before.
His work, based off of years of research and experimentation, was deemed debunked. People read about it online in press articles and decided that it wasn’t worth looking into. The BTD was now unscientific, just like all naturopaths apparently! Dr. Michael Greger, a highly biased vegan-diet-promoting doctor who cherry picks scientific studies and who I have even found to manipulate data to support his viewpoints published a critique. There was one on quackwatch too which is not a site I find trustworthy, to say the least.
As I have outlined in previous posts, like in a recent one about the saturated fat myth, science is often unable to study the complexities of reality. The study that “debunked” the blood-type diet did not really use the blood type diet. Dr. D’Adamo’s response to it addressed this and much more. His critique included that skeptics tend to never express curiosity. They come from a place of dismissiveness.
This was part of his response:
“A look at the core data used in the PLOS Study  debunking the Blood Type Diet (BTD) finds support for the researcher’s conclusions that if your experimental subjects eat potato chips, sandwiches, pizza, ‘beans,’ mac-and-cheese, French Fries and processed meat products while doing 13.7% of the Blood Type Diet, their final cardiometabolic markers will probably not vary much by blood type.”
If you want to learn about the blood type diet one day and read about how it was debunked but never do any research beyond that yourself, you have not honored your curiosity. You have not followed the scientific method. You have relied on “science” that someone else did to arrive at your conclusion about how things work. And you are wrong.
End of story.
I am not going to provide a detailed explanation on why I like the blood type diet. The main reason is that it is idividualized and based on trial, error, and lots of experimentation. Although I have no idea why some types can eat manchengo cheese and others cannot, I am open to the idea that some types may be more sensitive to certain proteins. I think that was his theory but I’ll have to save this discussion for a future post. There may be flaws to it but unlike other diets, it was devised by someone who seemed to put in more time and effort into it than people usually do it diet books. Based on these observations I do not think that the blood type diet debunking study came anywhere close to debunking the success stories people have had with it.