More inanity from our friend Null

OK, so it’s a repost from the old blog. I’m on vacation so gimme a break. –PalMD

When I get bored, I sift through the “articles” section of Gary Null’s site to see what kind of stupidity he is willing to host. Thankfully, it never takes long to find the stupid. This time, it was more on the so-called blood type diet. The article (not written by Null, just hosted on his site) is one of those wonderful oeuvres whose very title contains an unfounded assertion. Exposing falsehoods such as this may have its own benefits, but I would like to show how poor logic can easily lead to poor conclusions.

The assertion—that blood type and diet are related—is prima facie false and somewhat bizarre. It’s like saying eye color and urine volume are related—yes, both have to do with the human body, but what possible relationship could they have? On what basis should one assert this?

Let’s dispense with the pleasantries and move on to the take-down.

Anthropologists have speculated that blood types historically evolved due to changes in diet, culture, and social conditions. Due to these differing environmental factors, each blood type has particular strengths and limitations. When these tendencies are known and diet is modified to maximize an individuals genetic strengths, it becomes easier to maintain health. So, the first critical component of the blood type diet revolves around the question of which foods your blood type ancestors had available, and thrived upon.

First of all, ABO blood types are only part of the blood type story. Feel free to refer to any hematology textbook for the long, complicated story of erythrocyte proteins. It is almost analogous to skin color—“eat right for your skin tone!”—but what is your skin color? Black? Light brown? Pale peach? Skin color is a continuous spectrum with no sharp lines, so how would you know where to place yourself? With blood types, there are dozens of measurable types, and even more we don’t measure. There is no way to even know what your “type” would be.

Second, ABO blood types predate modern humans. Other non-human primates also have ABO blood types—there is nothing uniquely human about them.

Blood typing is useful in the fields of transfusion medicine and transplant medicine. There may be some geographic differences of some erythrocyte proteins. Sickle cell trait seems to confer some protection against malaria. It may be that other blood cell proteins are involved in this type of passive immunity as well.

But what you eat and what proteins are on your blood cells are two entirely unrelated topics. To simply assert that “[w]hen these tendencies are known and diet is modified to maximize an individuals genetic strengths, it becomes easier to maintain health” is pure foolishness.

So, the facts of the idea are false, but more than that, the reasoning is poor. Science works by making observations, and formulating testable hypotheses to explain these observations.

The blood type diet idea fails first on the observational level. There is no evidence of blood type and diet interacting to affect health. The fact that there is no plausible explanation of how this could be also raises red flags.

In order for this idea to hold any water at all, observational studies must show a measurable correlation between blood type, diet, and health. Then, someone has to come up with a biologically plausible reason for this correlation. Then, that hypothesis must be tested rigorously.

None of this has ever occurred. The blood type diet folks have made unfounded assertions, and used them to sell books. Either they are stupid, criminal, or both. My hypothesis: they are shameless.