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 alw