Skeptophilia (skep-to-fil-i-a) (n.) - the love of logical thought, skepticism, and thinking critically. Being an exploration of the applications of skeptical thinking to the world at large, with periodic excursions into linguistics, music, politics, cryptozoology, and why people keep seeing the face of Jesus on grilled cheese sandwiches.

Thursday, October 11, 2012

Menu planning by blood type

A few months ago, I wrote about the silly idea that in order to have a happy love life, you need to consider the compatibility of your blood type with that of your prospective romantic interest.  Additionally, your blood type predicts your personality, and what career your should pursue.  My general response:  "As if astrology wasn't ridiculous enough."  (Read my post about it here.) 

Now, to make matters worse, a major magazine has published an article that suggests that your blood type determines what you should eat for dinner.

Last month's issue of Men's Fitness had a piece, in amongst the usual fare featuring weight-lifting tips, bullet points about how to drive your woman crazy in bed, and photographs of shirtless guys with washboard abs, entitled "Eat According to Your Blood Type."  In the introduction to the article, the author, Lauren Passell, writes:
You feel like you’re doing everything right, health-wise. You eat salmon and quinoa, you exercise regularly, you even take the stairs. But if you're still plagued by midday lethargy, digestion issues or just can't lose weight, you might want to take something unorthodox into consideration—your blood type.

According to Dr. Peter J. D’Adamo, author of Eat Right 4 Your Type, whether you’re an A, B, AB or O, your blood type reveals eye-opening things about your personality and your body's needs. Here's what Dr. D'Adamo says about what foods and workouts will help you reach your blood type's fitness goals.
Myself, I think my midday lethargy has nothing to do with my blood type, but more to do with the fact that my dog likes to wake me up at three in the morning because he has an urgent need to play tug-of-war.  But let's see more of what D'Adamo has to say.

Type Os, he claims, are "descended from hunter-gatherers who relied mainly on animal protein to survive their strenuous lifestyles."  He also says that Type O is the "original blood type."

Well, right away, this sent up a couple of red flags.  Aren't we all descended from hunter-gatherers?  It's not like some of us come from proto-hominids in Africa, and others of us come from fruit bats.  And the thing about Type O being the "original blood type" is simply wrong.  The gene that codes for Type O blood is actually a mutated version of the Type A allele -- it has a single-base loss (frameshift mutation) that turns one of the functional codons into a stop code, causing the premature shutoff of translation of the gene and preventing the creation of a functional A antigen.  (The O allele, therefore, produces no functional gene product -- which is why it's recessive.)  The A allele is pretty clearly the oldest of the three ABO blood group alleles.

So this leads us to one important conclusion, to wit: don't make silly claims about genetics, because someone who actually knows something about genetics will call you out on it.

Let's move on, though, because I'm sure you other blood types will want to know what to plan for dinner.

Type As, D'Adamo says, gained the upper hand when agriculture was invented and the "hunter-gatherer Os started thinning out."  If you're Type A, you "have the digestive enzymes and bacteria it takes to digest grains and plants that other blood types might have a rough time breaking down."  Type As should limit red meat and fill their plates with vegetables; the best meal for a Type A is "tofu-pesto lasagna."  Type As also tend to have digestive upsets because they're "Type A personalities."  (I want you to appreciate how hard it was for me to write that last sentence without doing a faceplant directly into my keyboard.)

 Type Bs, on the other hand, "emerged when type Os moved to the Himalayas as nomads, domesticating animals and living on meat and dairy."  He did get one thing right, here, in the manner of a monkey pounding on a typewriter and eventually spelling out a real word; Type B blood has its peak frequency in India.  Otherwise, however, he's pretty much batting zero, because he says that Type Bs need lots of dairy products "because of a sugar present in milk," conveniently ignoring the fact that Type B is very common in East Asia, where the vast majority of people are also genetically lactose intolerant.


Type ABs, "the newest blood type," combine the characteristics of A and B (no surprise).  Their "low stomach acid" makes them "store meat as fat," so they need to eat lots of eggs.    I swear, I didn't make that claim up.  Go to the article, which I've linked above, if you don't believe me.

What appalls me most about this is not that D'Adamo wrote a book.  In these days of e-publishing, any yahoo with a computer can write a book.  (Note my links on the right side of the page.)  What bothers me is that a major magazine actually published this article, never once asking the critical question, "What is your evidence for all of this?"  (Not to mention the more important question, "Where did you get your medical degree?  Online Diplomas 'R' Us?")  The problem is, a lot of people don't think of questioning something that is written by a guy with "Dr." in front of his name, especially those of us who don't have a great background in science.  After all, the target readership of Men's Fitness is not scientists; it's just guys who would like to tone up and slim down (and drive their women crazy in bed).  So I'm sure after this issue came out, you had loads of very earnest guys going through their fridges and making sure that their food was in line with their blood type, instead of doing the simple thing that all of us should do, which is to eat a balanced diet and get plenty of exercise.  But of course, "eat a balanced diet and get plenty of exercise" isn't the kind of advice that sells books, or lands your ideas a national forum in a men's health magazine.

So, the bottom line; D'Adamo's claims are total horse waste.  Myself, I'm glad, because I'm a Type A, and I'll be damned if I'm going to give up my t-bone steaks for "tofu-pesto lasagna."


  1. I guess people can't help but shoot themselves in the foot... open-toed sandals providing direct access for the bullet. The only reason you'd need to know your blood type is for the transfusion you will undoubtedly require to recover from that self-induced injury.

    So close to having a credible claim, yet so far.

    I also find it interesting how someone could take some simple ideas, patently false but original in their construction, and extrapolate them into an entire book. 200 pages devoted to telling me what I should eat based on my blood type? Let me go out on a limb here and say that such hypotheses probably only need 10 pages at most, with the other 190 pages comprised of personal anecdotes and "best practices" that everyone is already aware of. Basically... filler, filler, filler, scientifically non-credible original thought, filler, filler, filler. $20 please!


  2. Larger fonts and greater word spacing helps a lot when getting to that page count that turns your pamphlet of ideas ($1.95) into a book ($19.95).