Gluten sensitivity: new epidemic or new myth?

Abstract

Fueled in part by recent bestselling books that warn of the evils of gluten in our diets, a significant proportion of our population is now either avoiding foods that contain gluten or eliminating gluten entirely from their diets, and these numbers continue to grow. The gluten-free trend—and the accompanying multibillion-dollar industry it has created—stems from the spreading belief that eating foods containing wheat or other gluten-laden grains may not only result in weight gain and obesity, but can also lead to a laundry list of ailments ranging from depression and anxiety to arthritis and autism. One popular book contends that current recommendations for a high-grain/low-fat diet underlie much of today's chronic health problems and that a low-carbohydrate, high-fat/cholesterol diet is ideal. Every major change in our diet carries with it the possibility of unforeseen risks. Concern about the impact of such popularized dietary recommendations on overall well-being—and on cardiovascular health in particular—warrants discussion in the medical community.

Fueled in part by recent bestselling books—and the television talk shows and celebrity endorsements that accompany them—that warn of the evils of gluten in our diets, a significant proportion of our population is rapidly changing its eating habits. Approximately 30% of all Americans are now either avoiding foods that contain gluten or eliminating gluten entirely from their diets, and these numbers continue to grow (1). The gluten-free trend—and the accompanying multibillion-dollar industry it has created—stems from the spreading belief that eating foods containing wheat or other gluten-laden grains may not only result in weight gain and obesity, but can also lead to a laundry list of ailments ranging from depression and anxiety to arthritis and autism.

In the book Grain Brain, for example, the author, David Perlmutter, lists dozens of diseases and symptoms that he believes are all related to gluten sensitivity and thus may be prevented or cured by a gluten-free diet. His list includes 38 different diseases or symptoms, including autism, infertility, and schizophrenia (p. 67) (2). He asserts that a low-carbohydrate, high-fat/cholesterol diet is ideal not just for those afflicted with celiac disease, but for most of the rest of us, as well. According to the book, “the alleged correlation between higher cholesterol and higher cardiac risk is an absolute fallacy” (p. 72), and the author entreats the reader to “start swapping out your daily bread with butter and eggs” (p. 12). Further, he charges that our nation's glorification of a high-grain/low-fat diet underlies today's epidemics of obesity, memory loss, and other common chronic illnesses, all of which is supported by uninformed physicians and a rapacious drug industry. It all makes for eye-catching reading and causational rhetoric.

A response is required.

The declaration that a single, simple “cure” can successfully treat numerous diverse diseases and symptoms is reminiscent of the oratory of the “snake oil” merchants of generations ago. These doctor-showmen plied their craft centuries ago in the sparsely populated areas of the American frontier and were known for their elixirs or “miracle cures” (which often included alcoholic admixtures of various nostrums). Of course, this was long before the development of placebo-controlled, randomized clinical trials, which have become the mainstay of proof of efficacy and safety in our modern era of health care.

According to Grain Brain, much chronic disease originates in the widespread ingestion of carbohydrates, and these foodstuff, rather than cholesterol or saturated fats, are the premier contributor to an unhealthy individual. Numerous recent studies, however, have provided high-level evidence to the contrary. A recent systematic review found several prospective cohort studies that demonstrated a relationship between consumption of saturated and trans fats and cognitive decline (3). A prospective study of a large heterogeneous population reported that a high-fat diet increases risk of specific breast cancer subtypes (4). A meta-analysis of 16 prospective cohort studies found that “higher consumption of fruit and vegetables [all containing carbohydrates] is associated with a lower risk of mortality from all causes, particularly from cardiovascular mortality” (5). Likewise, a multisite randomized controlled trial found that a low-fat, plant-based nutrition program reduced cardiovascular risk factors (6). Evidence-based findings such as these have led international panels to issue guidelines that recommend minimizing intake of saturated fats and trans fats and including whole grains as a primary staple of the diet (7).

Flaws in the arguments presented in the book have not entirely escaped the notice of health care professionals. Some have spoken up, calling the book “comfortably simplistic” (8), one of “brawn, not brain” (9). Others have charged the author with ignoring “the bulk of science,” exaggerating the truth, and making false assumptions (10), and have noted that the book makes claims that are contrary to “what some pretty reliable sources have to say,” referring to recommendations from the World Health Organization and Consumer Reports (11). Yet, the book remains a New York Times bestseller after 43 weeks, and sales of gluten-free products are projected to grow at an annual rate of 10.2% over each of the next 5 years (12).

Every major change in our diet carries with it the possibility of unforeseen risks. Many readers—the general public, as well as medical professionals—accept what they read at first glance. Myths have been part of our medical lore for millennia (13). Those jumping on the gluten-free/high-fat bandwagon may be disappointed when their symptoms are not mitigated; more critically, they may be at increased risk for other, more dangerous ailments. At the very least, concern about the impact of encouraging a high-cholesterol, high-saturated-fat diet warrants discussion in the medical community. In short, it is time to review some of the most egregious misinformation being spread and separate some of the wheat from the chaff.