Wait a minute, that's not right.
If a doctor writes a book about health... is it science?
This is the question I had in mind while reading Wheat Belly. When a physician like William Davis, MD, takes time out of his (no doubt) busy schedule to write a health-related book, ideally he has taken the time to get familiar with all the scientific literature on the topic. This may be easier for doctors than for some other writers, as Davis may have had the benefit of hearing research summaries at conferences, or having literature reviews arrive on his desk with the daily mail. Add that to years of clinical experience, and you have the potential for a pretty compelling argument on a health issue.
But what if, instead, a doctor seems to have spent years giving a certain piece of unusual clinical advice about a dietary change. And he has had such great success with patients who follow that advice that he goes looking for science to explain why it works. He scraps together a few studies that he thinks are relevant, connects some dots, and writes a book. What then?
Interesting, but not necessarily science.
So here's the heads up: Wheat Belly is an example of the latter. Though Davis, a cardiologist, has written a very interesting book with a timely message, you should know that it is not strictly based on science. Meaning: there is no thorough review of the evidence for his claims about the ill health effects of wheat.
Case in point: the glycemic index stats he cites are from an article published in 1981 - and he repeats again and again that the study found a greater blood sugar rise with "whole-meal" bread than with white bread, even though - ahem - a fair amount of glycemic index research has been done since, and a quick visit to almost any diabetes association website will confirm that whole wheat breads (for the most part) have lower glycemic indices than white breads. Davis gives a few nods to how his claims fit in, or don't fit in, with the advice of professional bodies. But he doesn't present a complete picture of why and how science shows that eliminating wheat from one's diet is a good idea.
One other reason I know he hasn't done a thorough review? I know about another body of science relevant to the topic, which gets little to no mention in Davis's book. That's the science to do with gut bacteria. But more on that after I summarize the book.
The point of the book is that it's bad to eat things that spike your blood sugar - i.e. things with a high glycemic index (GI). Apparently wheat spikes the blood sugar more than you'd expect - the oft-cited study found whole grain bread had a GI of 72, while a Mars bar had a GI of only 68 - and therefore we should eliminate wheat.
It follows that we should eliminate all things that spike blood sugar. Davis advocates this. So properly, the book should be called "Carb Belly". (Of course, the arguments against carbs have been well-explored in books that promote the Atkins diet, Paleo diet, Specific Carbohydrate diet, etc.) But Davis says the one carbohydrate that people have the most trouble eliminating is wheat. Hence, the name Wheat Belly.
Here's what's in the book:
Davis explains how wheat strains have changed with hybridization and how modern types of wheat affect us in unprecedented ways.
Davis describes wheat's "head-to-toe destruction of health": (1) the addictive properties of wheat that can influence behaviour and mood, (2) the way wheat triggers blood sugar and insulin extremes, which lead to visceral fat accumulation, (3) how intestinal permeability triggered by a protein in gluten may be responsible for the rise of autoimmune disorders and digestive disorders, (4) an argument that wheat may cause type 2 diabetes, (5) an explanation of how wheat affects the body's pH, resulting in an "acid-rich situation" and that promotes osteoporosis, (6) wheat's promotion of AGEs, which signal aging, (7) how wheat leads to heart disease by increasing triglycerides that turn into atherosclerotic plaque, (8) how the immune system's attack on nerve cells results in cerebellar ataxia and brain fog, and (9) how increased levels of insulin, and an immune reaction to gluten, can show up as acne or skin rash.
Note that for most of these claims, Davis's evidence is in the realm of the "theoretically possible." As far as I can tell, the science actually addressing these claims is weak. The studies conducted on humans where all else is equal, except the inclusion of wheat in the diet, are rare. Making his claims premature at best.
He talks about the "how to" of eliminating wheat and other carbohydrates. The book includes menus and recipes for low-carb eating.
- Evidence on how gut bacteria influences carbohydrate digestion throughout the lifespan
- Evidence on how bacterially-pre-digested white bread (a.k.a. sourdough) is metabolized differently from other breads
- Evidence on how fibre (prebiotics - known for their promotion of good gut bacteria) stimulate the immune system and increases the bioavailability of nutrients
He missed a few things. But can we really knock Dr. Davis for proposing a low-risk treatment that seems to work like magic for a host of health problems? Can we truly fault a compelling book that's convinced a lot of people to do something that clearly helps their health?
I think it's a good thing that he's written this book and that it's sold so widely. I'm biased of course, having been on a gluten-free diet for five years or so. It also doesn't escape me that it took a lot of bravery for him to so emphatically convey this message in a world that is very wheat-centred.
So yes, Davis has perhaps inspired many people to initiate a positive change for their health by penning a bestselling book with lots of media coverage. But by putting together a misleading scientific grab-bag of reasons for convincing people to make this change, he is assuring that they never fully understand what caused their health problems in the first place. They put on a bandaid without understanding what might have caused the wound.
...pretty well tell the same story as these: