blood type diet
January 31, 2010 2:15 PM   Subscribe

Is there anything to the specific blood-type diet?

I have a friend who has been doing really well since she went on a blood-type specific diet. She's doing marvelous, and some health issues have cleared up. Though my skeptical little scientist-self is skeptical about such diets, and I always though it sounded like a bunch of hooey, I'm wondering if there is something behind it? Mainly the blood-type antigen reacting to certain compounds in certain foods claim. Could it be for real? Thoughts? Experience?
posted by Maude_the_destroyer to Health & Fitness (17 answers total) 3 users marked this as a favorite
No. No, there is nothing to it. No, it can't be for real.
posted by Justinian at 2:20 PM on January 31, 2010

Many health issues can be improved by paying more attention to what and how we eat, and that kind of increased attention is typical for anybody who switches to just about any kind of planned diet. As long as the plan includes a sufficient quantity and variety of high quality foods, it will do more good than harm. The fact that other, less arbitrarily restricted eating plans are also capable of doing more good than harm is no reason to discourage somebody who is currently doing well on any given diet, even if they're doing it for completely bogus reasons.
posted by flabdablet at 2:38 PM on January 31, 2010 [3 favorites]

There are 30 different groups of antigens on blood cells with something like 600 different antigens identified. Is there a different diet for each one? Here is a good critique from a group that doesn't appear to be overly tied to conventional medicine.
posted by TedW at 2:40 PM on January 31, 2010 [2 favorites]

Mr. Lexica and I have found, over the 14 years since Eat Right For Your Type was published, that the closer we adhere to the blood type diet's recommendations as far as foods to avoid and foods to emphasize, the healthier we feel.

The website has a lot of information about the scientific basis of the diet here.

I don't talk about it much, and I don't volunteer information unless asked. There are too many people who shout "quackery!" based on the mere idea that one's blood type could be important this way. Whatever. As far as I can tell from my layperson's perspective, Dr. D'Adamo isn't misrepresenting the research. And my first-hand experience overwhelmingly tells me he's on to something valid.
posted by Lexica at 2:44 PM on January 31, 2010

Unadulterated pseudoscientific nonsense.

It's very much just (1) Do some 'research' which involves not really understanding a load of other people's genuine research, (2) Link it all up in a way that is totally without scientific basis, but makes some kind of sense to your over-credulous audience, (3) Write a book and go on tour.

Any positive effect is incidental and comes from people paying more attention to their diet and not eating so much crap.
posted by le morte de bea arthur at 2:48 PM on January 31, 2010

Best answer: There is something to it. A lot of money flowing into the pockets of the people that made it up. Add in the usual true believers who've been sucked in to the point they don't even care that the science is bunk touting the diet to others (see Lexica above) and that money keeps flowing. Realising you've been sucked in by a quack goes against most people's sense of pride and rationality and these people have a lot invested in continuing to believe even when they should know better.

I'm a biochemist. I work in the area of personalised nutrition, looking specifically at how food interact with each person's underlying genetics (which is exactly what this diet is trying to do). If this worked we'd be all over it, believe me. However it has no scientific merit at all. The changes the diet makes are non-specific enough that they will work for some people, just like any diet changes will. that's enough to create those true believers and the marketing does the rest.
posted by shelleycat at 2:53 PM on January 31, 2010 [18 favorites]

Certainly, there are people who have benefited by following the advice in those books. There are people who have benefited by following the advice they got in fortune cookies too. And look, if you stumble onto an idea that works for you, then that's great, no matter how you got it.

But those books aren't a reliable source of diet advice any more than fortune cookies would be. Sometimes you get a fortune with a helpful suggestion; sometimes you don't. Some people's blood type "matches" the foods that make them feel good; some people's blood type doesn't.
posted by nebulawindphone at 2:59 PM on January 31, 2010 [1 favorite]

Like I said, I don't talk about it much, for exactly these reasons. You all want to explain how my choosing not to eat tomatoes and dairy is somehow pumping money into the pockets of scammers, go ahead and try. You want to explain the mechanisms by which tomatoes and dairy make me feel physically unwell for several hours after I eat them, go ahead — that would be more useful.

All I know is that by avoiding the foods he says are bad for my blood type, I feel healthier. Nothing to buy, no programs to join, just avoiding certain foods that, when I look back, have given me trouble all my life.
posted by Lexica at 3:08 PM on January 31, 2010

If you believe in cause and effect, then it's bogus and dangerous nonses validated only by anecdote, delusions, and the placebo effect. Naturopaths like D'Adamo are using a discredited theory of health involving "humours" of the blood and organs that Western medicine abandoned by the middle of the 19th century because it had notably failed to actually predict or heal disease in any meaningful fashion. None of the "science" referred to by naturopaths is anything more than badly garbled facile and surface misrepresentations of scientific knowledge arranged into a systemic structure that makes no logical sense and is insulated against falsification or effect-based modification of its principles. The ABO blood type system is only one of the may ways to categorise the different patterns of glcoproteins expressed on the surface of certain clades of cells within human bodies. Other blood type categorisation systems include the {A1,A2,B1,O1,O1v,O2} allelic system, the Hh Bombay, cis/trans AB, {C, c, D, E, e} Rhesus system (including about 50+ others too numerous to list), the Duffy {Fy(a+b+), Fy(a+b-), Fy(a-b+)}, etc, etc, etc. This impressive complexity is not something that can be distilled into a nice, simple prescription for diet, so naturopaths have chosen basically to ignore it.

Even D'Adamo's basic "just-so" story that the O genotype evolved "first" among humans turns out to be based on nothing more than personal prejudice. The Evolution of the O alleles of the human ABO blood group gene article quite clearly demonstrates that the O group evolved later than the AB system in humans.
posted by meehawl at 3:19 PM on January 31, 2010

I'll actually put money on this bet:

Take any random person.
Put them on any set diet that is balanced...and made for a different blood type.
Watch their overall health get better.

Most people who run to these diets do really well...because they are finally eating healthy.

Does it have to do with their blood type? No.
posted by hal_c_on at 3:23 PM on January 31, 2010

All I know is that by avoiding the foods he says are bad for my blood type, I feel healthier.


Can you please provide me with some info about your specific diet and why it fits you according to the book (specific blood type, etc)? Right off the bat, I'm telling you that I don't buy into this stuff. But i am really interested to see whats working for you.

I think posting here would benefit not only the OP but everyone watching this thread. If you don't mind, that is...
posted by hal_c_on at 3:26 PM on January 31, 2010

You want to explain the mechanisms by which tomatoes and dairy make me feel physically unwell for several hours after I eat them, go ahead — that would be more useful.

This is actually exactly what nutrigenomics is trying to do. Unfortunately quacks pushing pseudoscience make our job harder, and it is way more complicated and personalised than the blood type diet will have you believe. Doing so in your case would involve at the least a full medical work up, food diary and probably some gentoyping. Not choosing an arbitrary set of antigens present on a single cell type (because, as Tedw has mentioned, there are many other antigens present in your blood that are not included in this diet but are otherwise just as biologically relelvant) then throwing in a fad diet from a list.

just avoiding certain foods that, when I look back, have given me trouble all my life.

Which should also be possible (even relatively easy) to do without buying a book in the first place. It also doesn't mean the overall system is valid or that you should recommend it, remember that this blood type thing is all based on selling products (the book being number one but there is other stuff you can buy too). The authors research isn't valid, the diet isn't valid, there is no science here.

The evangelistic laypersons opinion exactly as Lexica has presented it above is the quack's number one marketing tool. Not only does it get more product to sell but it gives deniability when the claims being made go beyond what the science supports, since it's not the company themselves making them. The FDA can regulate claims made by the person selling the system but not so easily those made by enthusiastic recruits (see also the OPs friend), so the pseudoscience persists.

(Also, as another data point: my mother was into this for a while and the diet which her book said I should eat included several of my IBS/GERD triggers and would have made me entirely miserable. But you don't usually get stories like that on the internet because they're boring.)
posted by shelleycat at 3:30 PM on January 31, 2010 [5 favorites]

Also note that tomatoes and diary are trigger foods for lots of people and for many geastrointestinal health problems, removing them from any random person's diet and ther's a chance it will change something. The blood group diet my Mum tried involved cutting out all simple sugars and refined carbohydrates, again something which will have positive health effects in some people. My sister went to a naturopath once who told her to cut out all wheat and gluten, again something which affects a reasonable proportion of people and has a non-trival chance of success.

The way these kinds of diets work is they cut out things which are already known to have a high chance of doing something in some people. When it doesn't work the person blows it off and moves on (in which case no loss, they already bought the book), when it does the person is converted then tells others how great it is. And so it goes.
posted by shelleycat at 3:36 PM on January 31, 2010 [1 favorite]

This pseudoscience has no clinical trials and has been subject to no peer review. That's enough for me to say "no thanks dude".

Also my blood type supposedly "thrives on dairy products," which, EPIC LOLZ, as native americans tend to be incredibly lactose intolerant.
posted by elizardbits at 3:53 PM on January 31, 2010

You all want to explain how my choosing not to eat tomatoes and dairy is somehow pumping money into the pockets of scammers, go ahead and try. You want to explain the mechanisms by which tomatoes and dairy make me feel physically unwell for several hours after I eat them, go ahead — that would be more useful.

All I know is that by avoiding the foods he says are bad for my blood type, I feel healthier.

Sensitivities to the acid in tomatoes and the lactose in dairy are very common, regardless of blood type; literally millions of people feel better when they don't eat them, whether they are O-negative or A-positive or any other blood type.
posted by scody at 4:40 PM on January 31, 2010

The comments so far are spot on, though if you have questions about improving your diet the kind of person to ask them to is a Doctor or, more specifically, a Dietitian. Going to nutritionists and folks with similar sounding titles is like going to a toothologist when what you really need is a dentist. Dietitians, like dentists, must have X number of years of training and go through important regulatory hoops to prove they are qualified to handle your diet.

You'd be amazed at all of the non-obvious ways in which someone who doesn't know what they're doing messing with someones diet can be just as uncomfortable and dangerous as you would imagine an unfortunate encounter with a toothologist would be.
posted by Blasdelb at 4:43 PM on January 31, 2010

Response by poster: I should add that I'm not interested in changing my diet, my question was more just out of curiosity.

My friend did not eat crap prior to switching, (we are urban hippie, grow-your-own-kale types) so it wasn't just the fact that she was suddenly eating a balanced diet. I'm really impressed with the results of her switch. I'm in the biological sciences myself, but a little too lazy/busy today to wade through all the literature regarding blood types (I was already aware that it's much more complex than ABO).

Thanks everyone for your thoughts!
posted by Maude_the_destroyer at 6:20 PM on January 31, 2010

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