Jan 24 2014

Kicking Bubbles

A look at the core data used in the PLOS Study [1] 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.

In other words, whilst the PLOS Study may have debunked something, it wasn’t the Blood Type Diet.

Laying aside my initial concerns about the study expressed in the previous blog, many of which were responded to personally by Dr. El-Sohemy, there remains the one over-arching issue: How accurately did the PLOS study model the Blood Type Diet? Despite Dr. El-Sohemy’s extensive response, this was the one point for which he chose to not answer. Since no clarification was forthcoming, I decided to seek out the answer for myself.

Soap bubbles

This turns out to have been quite easy, since the food values used in the PLOS study were included as a table in an appendix. [3] From there I simply prepared a spreadsheet with the corresponding values from my book Eat Right For Your Type (ERFYT)[2] and the PLOS Appendix, when a value in the appendix was available, which as you can see by clicking on the link below, was not very often. I then wrote a short program in Perl to run some simple analytical and counting functions.

Click Here to Read the Full Article

I started by simply comparing the incidence of values that  appear in ERFYT and the corresponding values that appear in the PLOS Study.

These appear as Table 1.

The results were even worse than I expected. An enormous number of foods containing values in ERFYT are missing values in the PLOS Appendix. Out of a total of 540 food values available in ERFYT (excluding ‘Herbs,’ ‘Beverages,’ and ‘Teas,’) only 74 (13.7%) show equivalent values in the PLOS Appendix. It’s easy to see the number of foods missing foods from the PLOS appendix in Table 1. They are the large chunks of grey-colored boxes in the table with the label ‘n/v’.

There are also a considerable number (822) of instances of foods containing specific values (being rated as either ‘beneficial’ or ‘avoid’) in ERFYT but having no equivalent values in the PLOS Appendix. In these occurrences, subjects consuming any of these foods would not have had their effects represented in the PLOS study.

In addition, there are no equivalent values in the PLOS Appendix for a large number of the foods (281) for which ERFYT supplies at least two blood type specific values.

Finally, there are a sizable number (77) of foods for which there are values in ERFYT that differ by blood type (i.e being a ‘beneficial’ for one blood type and  ‘avoid’ for another) that were not included in the PLOS Appendix. This number is especially pertinent, because a considerable number of foods where variation by blood type might have been expected were not included in the PLOS study. When the non-ERFYT equivalent foods are excluded (see Table 2) the number of foods missing from the PLOS Appendix containing values that vary by blood type is actually greater than the total number of  foods included in the PLOS Appendix  (74).

Then I looked at the food values used in the PLOS-BTD Study that have no equivalent value in ERFYT.

This appears as Table 2.

These results went from bad to ludicrous.

A total of 37 foods are classed in the PLOS Appendix as possessing BTD values despite having no direct representation in ERFYT. This appears to have resulted from study force-fitting foods from the Toronto-modified Willet 196-item semi-quantitative food frequency questionnaire (TMW) into the food framework of the BTD. However, many of these foods are complex combinations of various single ingredients (‘sandwiches’), or entire categories of foods (‘beans’). These ‘lumped categories’ often possess unknown BTD values, or contain  individual foods with specific BTD values that contradict the values assigned to the total category  by the PLOS authors.

There are several assumptions about the nature of these complex foods which lead to error. For example, ‘mac and cheese’ is listed as ‘neutral’ for blood types A, B, and AB in the PLOS Appendix, despite the fact that the dish is almost universally prepared with processed American cheese, which is clearly indicated in ERFYT as an ‘avoid.’ Pizza is listed as a ‘neutral’ for blood type A, when in fact pizza is almost always prepared with tomato sauce.  Tomatoes are clearly indicated as an ‘avoid’ for this blood type. ‘Hamburger’ is listed in the PLOS Study as ‘beneficial’ for type O, despite the fact that hamburgers are universally served on a wheat bun. Wheat is clearly listed as an ‘avoid’ for blood type O in ERFYT.

Many of the PLOS Appendix foods listed in Table 2 are these sorts of lumped categories, including ‘tropical fruits,’ ‘cooked breakfast cereal,’ ‘sandwiches,’ ‘mixed vegetables,’  ‘grains, other,’  ‘beans,’  etc. These generalizations have the effect of negating many of the BTD-specific food values, in particular the blood type specific lectin reactions. For example, the generalized category ‘beans’ are listed as ‘beneficial’ for blood type A in the PLOS Appendix, when in fact lima beans, in particular, contain a known hemagglutinating lectin specific for that blood type. [4]

In these circumstances, it appears that the PLOS authors chose to stick with the TMW food descriptions and shoe-horn the BTD values into the TMW. This yields a variety of questionable assertions, such as whether a category simplified into ‘beans’ can be given any sort of BTD value at all. In virtually all the instances of the ‘food-lumping’ seen in Table 2, when the TMW ‘food’ is actually split into BTD values the process yields erroneous conclusions. The PLOS Study does not provide any insight into the process used to determine the BTD rating for foods such as ‘mixed vegetables,’ ‘grains, other,’ etc. but the grading system appears quite arbitrary.

It is well-worth wondering how a study with such basic flaws in its design could have survived peer-review. I assume that the reviewers spent adequate time surveying the basic statistical functions used in the study, but I seriously wonder if any of the reviewers took the time to look  at just how closely the PLOS study modeled the BTD. It seems improbable that any of them spent time with a copy of  Eat Right For Your Type on their laps, cross-referencing its values with the PLOS Appendix. Yet this is perhaps the most basic question to ask of this study: Did it comprehensively model the BTD before reaching its conclusions? A look at the cross-comparision tabular data clearly indicates that it did not. Because of this very basic design flaw, all subsequent analysis and conclusions are moot; they derive from an improper, inaccurate, experimental model.

That the BTD theory is currently unproven by rigorous scientific study is not argued. In time this can be rectified by studies which accurately and comprehensively prove or disprove the hypothesis. Despite the rejoicing in certain circles [5] the Blood Type Diet/PLOS study by El-Sohemy, et al. is not that study. I call upon the editors of PLOS ONE to consider retracting this study unless they can justify the scientific basis of these concerns.

Click Here to Read the Full Article

  1. Jingzhou Wang,Bibiana García-Bailo,Daiva E. Nielsen, Ahmed El-Sohemy. ABO Genotype, ‘Blood-Type’ Diet and Cardiometabolic Risk Factors. PLOS ONE DOI: 10.1371/journal.pone.0084749
  2. Peter D’Adamo, Catheine Whitney. Eat Right For Your Type. Penguin-Putnam Publishers 1996
  3. Appendix S1 of the PLOS Study
  4. Sikder SK, Kabat EA, Roberts DD, Goldstein IJ. Immunochemical studies on the combining site of the blood group A-specific lima bean lectin.Carbohydr Res. 1986 Aug 15;151:247-60.
  5. NeuroLogica Blog: Blood Type Diet Disproved

12 responses so far

12 Responses to “Kicking Bubbles”

  1. Ahmed El-Sohemy says:

    Dr. D’Adamo,

    Thank you for taking the time to review our study more carefully. I will prepare a response and post it here soon. In the meantime, there remains one critical issue that you have not yet addressed. You state “That the BTD theory is currently unproven by rigorous scientific study is not argued.”
    So, what happened to that 10 year trial on blood type diet and cancer remission you described in your book?:

    “Even now, as I write this, I am beginning the eighth year of a ten-year trial on reproductive cancers, using the Blood Type Diets. My results are encouraging. So far, the women in my trial have double the survival rate published by the American Cancer Society. By the time I release the results in another two years, I expect to make it scientifically demonstrable that the Blood Type Diet plays a role in cancer remission.” – Peter D’Adamo (p 307, Eat Right 4 Your Type, 1996).

    Where are the results of this study you claim to have conducted? I will work on a response to the comments you raise in this blog and I would hope that you will work on a response to this simple question.

    AE

    • Ahmed,

      Sorry, but I am a not going to play your little game here. What I wrote in 1996 has very little to do with what you wrote in 2014. Perhaps if I felt your question insinuated less, I would provide an answer, but since I do, I won’t. You can ask around, or troll my website (as pastime you seem to enjoy) and find the answer there. In the meantime I’lll just eat my mac and cheese and lima beans.

      PD.

      • Ahmed El-Sohemy says:

        PLoS ONE Study on Blood Type Diet Fails to Account for Hundreds of Irrelevant Foods and Ignores Intake of Frogs, Turtles and Squirrels!

        Judging by your ‘analysis’, this would have been a more appropriate title for your post. Once again, your criticisms of our study continue to be false, misleading and irrelevant.

        You claim that we failed to account for 466 food items (540-74), yet almost 300 of these are considered neutral for just the AB type diet alone, and a whopping 426 of these are neutral for at least one of the blood type diets. What is the relevance of including a food that your book describes as neutral, and it doesn’t matter if a person consumes it or avoids it? Including those foods to grossly inflate your numbers of missing foods from our study leads to one of three possible conclusions:
        1. You do not understand the scoring system we described in our study where beneficial foods received a score of +1, avoid foods a score of -1 and neutral foods a score of 0.
        2. You are unaware of which foods in your book should be avoided or consumed based on blood type because you realize there’s actually no science to support such claims.
        3. You are misleading your readers in a desperate attempt to discredit our study.

        Putting aside those hundreds of neutral foods that have no impact on the blood type diet scores whatsoever, if we look at the foods that are described as beneficial or should be avoided we find a list of many exotic and unusual foods (eg frogs, turtles, squirrels, etc…) that our population just doesn’t consume. There’s also that very long list of different kinds of fish, many of which are exotic and not readily available here either. So even these beneficial or avoid foods are considered irrelevant for our population.

        Regardless of which of the 3 reasons I proposed above led you to distort the numbers in your analysis, it reveals that you are unwilling to engage in an honest scientific discussion. If you were, then you would have answered the simple question of what happened to that 10 year cancer study you refer to in your book so we can reconcile the inconsistencies between your blog and your book. It is indeed quite fishy that you refuse to answer this one simple question that many are now asking.

        AE

        • Ahmed says:

          ‘You claim that we failed to account for 466 food items (540-74), yet almost 300 of these are considered neutral for just the AB type diet alone, and a whopping 426 of these are neutral for at least one of the blood type diets. ”

          Peter says:

          “There are also a considerable number (822) of instances of foods containing specific values (being rated as either ‘beneficial’ or ‘avoid’) in ERFYT but having no equivalent values in the PLOS Appendix.”

          “In addition, there are no equivalent values in the PLOS Appendix for a large number of the foods (281) for which ERFYT supplies at least two blood type specific values.”

          “Finally, there are a sizable number (77) of foods for which there are values in ERFYT that differ by blood type (i.e being a ‘beneficial’ for one blood type and ’avoid’ for another) that were not included in the PLOS Appendix. ”

          Peter says:

          “A total of 37 foods are classed in the PLOS Appendix as possessing BTD values despite having no direct representation in ERFYT. This appears to have resulted from study force-fitting foods from the Toronto-modified Willet 196-item semi-quantitative food frequency questionnaire (TMW) into the food framework of the BTD. However, many of these foods are complex combinations of various single ingredients (‘sandwiches’), or entire categories of foods (‘beans’). These ‘lumped categories’ often possess unknown BTD values, or contain individual foods with specific BTD values that contradict the values assigned to the total category by the PLOS authors.’

          Ahmed says:

          Nothing.

          Ahmed says:

          “You are misleading your readers in a desperate attempt to discredit our study.”

          Peter says:

          Numbers always beat words.

          Ahmed says:

          “..you are unwilling to engage in an honest scientific discussion. If you were, then you would have answered the simple question of what happened to that 10 year cancer study you refer to in your book so we can reconcile the inconsistencies between your blog and your book. ”

          Peter says:

          Nice way to defend your study. What a lame, Machiavellian response.

          • Ahmed El-Sohemy says:

            Peter says “Numbers always beat words.”

            Ahmed says “Sure, if you continue to just make up numbers.” You just presented an ‘analysis’ using hundreds of irrelevant numbers and when you get called on it you have nothing to say about it except to ask us to believe some other numbers you’ve come up with. Whatever credibility you may have had is taking a steep nose-dive here.

            My final words to you Dr. D’