I tend to think that when they start throwing ad hominems at you, it is a sure sign of victory.’

–Christopher Hitchens

One of the things I’ve never quite understood about the proponents of the various assorted theories of nutrition is why, for many, the only way to prove your method is by denigrating of the methods of others. Most of the time we’re talking about money, and occasionally, lots of it. Perhaps such is the case for the so-called ‘DNA Diet,’ whose marketing strategy seems to rely on the fact that it is ‘better than the Blood Type Diet (BTD)’.

Perhaps it is. However the poorly-chosen means by which they make their argument seems to imply that they are stupendously ignorant about the basic effects of blood group genetics on physiology. Thus, yet again, your humble blogger is forced to participate in another episode of cheerless infanticide.

These DNA Diet tests are typically direct-to-consumer (DTC) panels of single nucleotide polymorphisms (SNPS) that look for variations in genes that control a diverse number of body functions, such as inflammation, clotting, and detoxification. Lifegenetics is one of the many purveyors of this technology. Others include 23 And Me and multi-level marketers such as Amway and Market America. In a recent New England Journal of Medicine article the ultimate value and benefit of these DTC SNP panels has been called into question. Several authorities have made the point, quite clearly, that molecular diagnostics still have a long way to go before they can properly deliver on all their promises.

Who to believe: Me or your lying eyes?

‘The Blood Type Diet is OUT, the DNA diet is in!

Lifegenetics, marketers of the DNA Diet, breathlessly announce in bold headlines across a gotcha page that compares the Blood Type Diet with the DNA Diet and concluding, not surprisingly, that the DNA Diet is far superior.

Unfortunately, a closer examination of their claims yields no such certainty. Indeed the presentation of the evidence is at times so skewed, and the selected points so cherry-picked, that one wonders how supposed experts in nutritional genomics could be so willing to ignore basic and widely known facts about a very well-studied gene. Let’s take a look:

This diet was started by American Peter D’Adamo. It was founded on observations of his father, a physician James D’Adam [sic], who has alleged that certain blood types are associated with the response to different types of food, and even the type of personality.

True but. The use of the word alleged is a bit snarky, but I suppose acceptable. Like my father, I am a physician. I am indeed American, though I consider myself more a ‘citizen of the world’. Neither myself or my father alleged anything about personality, other than report that it was the object of intense interest in Japanese pop culture. However, there are, had Lifegenetics actually consulted the standard medical reference databases, numerous studies showing links between ABO blood genetics and other genes that do influence nervous function, such dopamine beta hydroxylase, which has been linked to differences in ABO blood group. I’ve made a strong case that ABO does indeed influence many elements and parameters of the digestive tract, including tissue glycosylation, intestinal alkaline phosphatase secretion levels (which controls much of how we process dietary fat), our stomach acid secretions, blood viscosity and even the makeup of our intestinal flora (microbiome).

The whole idea is based on one of the 30 up-to today known systems of blood groups, AB0 system. AB0 group is usually determined from the drop of blood using different reagents. It is therefore a serological and not a genetic test, as some think. It is true that our blood group is written in the genes, but it has no scientifically proven link with the metabolism of our body’s response to food.

This is utter bullocks. Although ABO is one of the many blood grouping systems, the effect of ABO blood type on phenotype (the process by which genetics influences our eventual physical characteristics) is greater than all the other blood systems combined. ABO controls much of the immune reactivity of our tissues –which is why organs must be matched to ABO blood type when transplanted. Your ABO blood type is sprinkled all over your digestive tract, especially in the secretions and protective mucus. It’s ironic to me that they choose to differentiate a serologic test versus a genetic test, as if the methodology in some way led to a different conclusion –other than the fact that former is about 5% of the price of the latter. You could easily determine ABO type via genetic SNP analysis; but the ABO antigens are so biologically prevalent that there is simply no economically viable, common-sense reason to do it.

Basically, every person needs a balanced diet that allows him or her to get all the micro-and macronutrients, essential for the normal functioning of the body, so the exclusion of any food without professional good reason can be dangerous. In the case of eating by blood type diet makes it difficult to understand why many people should not consume certain types of food (such as those containing gluten – which is known to cause problems only to individuals with Coeliac disease).

Not much of a point here. Pray tell, what is a ‘balanced diet’? To my line of reasoning ‘balanced diets’ are what got the largely obese and deconditioned Western world into problems in the first place. A rudimentary analysis of any of the suggested diets for the blood types easily shows that they are nutritionally complete, and indeed even at their extreme represent healthy versions of other current one-size-fits-all diets: The basic type O diet is a healthy low-carb diet, the type A diet is a very healthy Mediterranean type diet. Many individuals, particularly blood group A, seem quite healthy despite the exclusion of certain foods ‘without professional good reason’. Here on planet Earth we call these people “vegans”.

If we look into the databases of journals and scientific papers, we do not find a single research or clinical study by Peter D’Adamo that could scientifically support his theory. Digestion and metabolism are very complex processes, dependent on hundreds of parameters. Therefore any generalization of their properties and furthermore prescribing certain food groups on the basis of a single variable, such as blood type, is pointless. A simple proof for that is a quick look at the blood types of the population of adults with lactose intolerance (who in fact should avoid eating dairy products) – we can find people with all blood types that are lactose intolerant.

There is no shortage of publications written by yours truly on the importance of blood groups available. I’ve even written a textbook on the subject. It is true that lactose intolerance is not predictable by blood group. It is also true that most people who are lactose intolerant do not need a very expensive genetic test to figure this out for themselves. Incidentally, a scan of Medline (PubMed) for any studies associated with the term ‘LifeGenetics’ did not yield a single result.

Follow the money.

A quick tour of the website offered some other interesting points of comparison. Concerned about that mid-life sprawl? Why not order the ‘DNA Slim Test'(249 Euros, 327 USD). Ever-anxious new parents can order the ‘DNA Test Baby Panel’ (299 Euros, 393 USD) to make sure their kid is all there. Why stop? LifeGenetics can supply you with a ‘Complete Healthy Makeover’ for the small sum of 399 Euros (525 USD). In terms of profitability, the BTD does indeed makes a rather poor showing. One can usually find out their blood type for free at any blood bank or blood drive; lacking that availability, FDA-approved home blood typing tests are available for under 10 USD.

It’s disgraceful when a supposedly science-based corporation feels a need to market their products in this manner. Yet, in a way, I can understand why Lifegenetics would feel such a need to disparage the me and the BTD. The BTD books are worldwide multi-million copy bestsellers and the concept has huge name-brand recognition. In other words, in some scientific circles, my work would be more likable if it were just not so wildly popular. I suppose they just resent having to answer questions about the BTD all the time. Many corporate dinosaurs have yet to realize that this type of marketing does not work in the age of social media, and when the chosen target so chooses to confront assertions with facts, can risk becoming converted into a form of self-immolation.

Personally, I lost interest in SNPs long ago when I became aware of the more direct effects that diet had on gene expression via the various epigenetic mechanisms.

Tags: blood type diet | DNA Diet