9/11/09

Last night Dr. Andrew Weil was on the CNN's The Larry King Show. Dr. Weil, reacted to a question about blood types and diet with the response that he thought of the BTD had "no scientific basis". He verified this by saying that if people tested the blood of dogs they would say they should be vegetarian rather than carnivores. I have already addressed this mistaken assertion of Dr. Weil's (humans and other species glycosylate their tissues differently, and linkages of certain physiologic functions to the blood group genes also vary by species), but it seems that he needs to keep re-asserting this incredibly naive argument.

In a series of rotating criticisms Dr. Weil other venues asserted that the problem with the BTD was that he "sees no convincing link between lectins and the molecules which determine blood type." (AARP Magazine) After being subsequently challenged by numerous editorial letters, he eventually responded that "he did not agree with restrictive diets." I've previously responded to Dr. Weil's assertions in this blog, but wanted to resurrect my most recent response and make it a bit more current.

Finally I'd like to challenge Dr. Weil to an open forum discussion of the scientific merits of the theories and associations developed, observed or reported by myself and my father. This can occur at any time or place of his choosing. If he is as committed to investigating the truth of his assertions as one would suspect, I have no doubt that he will be as anxious as I for this to occur. I can be contacted through this blog, or at my clinic.

[Now on to the previous blog entry]

8/18/08

The more I read of Andrew Weil's efforts to debunk the work of my father and myself, the more I'm convinced I can't simply turn the other cheek and let these so-called skeptics just get away with disingenuous portrayals of the science behind this diet. His recent slag-job in AARP Magazine is just more proof that I will need to react in a timely and concise manner going forward.

"D'Adamo theorizes that the basis for such differences is our reactions to certain food proteins called lectins. Lectins are common in plant foods, especially grains and beans, and may be involved in food allergies and some immune disorders. But there is no convincing evidence for any interactions between lectins and the molecules that determine blood type."

"Yet some people swear the blood type diet has worked for them. There's a reason for that. Making changes in how we eat is not easy. To follow any prescribed dietary program with rules and restrictions represents a significant commitment of mental energy toward self-improvement. That alone can lead to a greater sense of well-being and better health. But if you want to eat a better diet, I recommend you rely on information grounded in nutritional science."

I think I got on Dr. Weil's bad side a few years ago when I replied to a question posed to me about my recommendation that blood type As eat peanuts, while Dr. Weil was saying that peanuts were dangerous because of the aflatoxin. My response was that this was a silly piece of advice since the only place you can get aflatoxin is in health food stores when you grind your own peanut butter; all the commercial forms must be assayed for it before they can be sold.

Over the next few years Dr. Weil kept up a consistent attack on me and the theory, usually basing his case on the rather odd observation that animals have blood types and yet don't follow the Blood Type Diet.

However with the AARP column Dr. Weil instead shifted to what he considers the lack of proven association between dietary lectins and blood groups.

It's a bad place to pick an argument, since at that point the argument moves up the academic ladder to areas he would be wise to not tread. There are numerous and well-documented links between lectins and blood groups. Searching MEDLINE for the terms ABO Blood Groups and Lectins yields 687 published studies[0] In fact the term ‘lectin’ was derived in 1954 from the Latin for legere, to pick or choose, it having been coined thus to call attention to their blood type specificity.

Dr. Weil's claim appears to have not been researched to any great degree since it appears to me to have been taken from an incorrect assertion that often finds its way onto the Wikipedia entry on the Blood Type Diet.

In fact, blood group specificity is listed as one of the nine major factors influencing glycosylation in the gut (glycosylation is the process of manufacturing the sugar molecules that lectins bind with). Other factors include diet, age, animal species, disease and bacterial population.

Independent of the lectin hypothesis, in my opinion the secretory differences (digestive enzymes, etc.) between the blood groups are an even more significant reason behind the need for the tailoring nutritional needs to these genetic markers.[1] But Dr. Weil doesn't know about these links or chooses to ignore them altogether. Then again, every critic seems to have their own favorite aspect of the theory.

Given his harsh take on my work, it was surprising to read some of his statements about the need for keeping an open mind about alternative medicine. Kinda wish he would practice what he preaches. In a reply to one of his own critics (Arnold S. Relman, editor-in-chief emeritus of the New England Journal of Medicine)[2], he writes:

"As a researcher, you have the luxury of insisting on rigorous scientific testing, and you have the leisure to wait for results to come in. As a practitioner, you are in the trenches, working with patients who have medical needs. And you often have to guess, and you have to make use of your best medical judgment in the absence of definitive evidence."

No argument there.

"In my experience-- I consider experience to be one valuable source of data--many patients use alternative methods because they find that they work. And if a patient has tried a method and found that it works, that patient needs no further proof, does not need to read the reports of a randomized, double-blind, controlled trial in a medical journal to be convinced of the efficacy of treatment."

Even better.

"I don't think you can have it both ways; you can't demand evidence, and then when evidence comes in that contradicts your preconceptions, say you aren't going to look at it."

Words to live by.

Now if Dr. Weil were to keep an open mind, I'd recommend that he read up on the work of William Boyd, who first wrote of the blood type specificity of lectins more than a half centry ago [3] or review the research of Martin Nachbar[4] from the 1980's. Lots of interesting stuff there. A trip to MEDLINE would also be helpful.[5],[6],[7]

In an article critical of Dr. Weil written for the New Republic Relman touched on many of Weil's factual inconsistencies and concluded that:

Weil considers himself an authority on almost every field of medicine. [8]

Finally, it could be argued that the possible reason Dr. Weil supplies for why some people swear that the blood type diet has worked for them ("a significant commitment of mental energy toward self-improvement") may well be the exact same reason some people derive benefits from his own books, tapes and recommendations!

But let's at least end on a somewhat positive note, with a quote from someone who does have experience with lectins. Gerhard Uhlenbruck is one of about three or four top lectinologists of the last century and renowned for discovering the structure of the Thomsen-Friedenreich antigens and the structure and specificity of (aflatoxin-free, I'm sure) peanut lectin. This is what he recently said:

When I first heard of Peter D'Adamo's blood group diet, of course I was very skeptical: Should we have missed in our book (Prokop/ Uhlenbruck: Human Blood and Serum Groups) such an important aspect? But years later, my interest switched to the nutritional field while working on the so-called Metabolic Syndrome, my interest increased in studying the role of genes in metabolic processes. I found out, that Peter D'Adamo's blood group orientated diet could probably be a first step in the right direction..

Back soon with a more positive, happy and helpful blog.