The Great Gluten Panic: Risk assessments and facts
(Note: The following is by guest contributor Stan Cox, adjunct professor of agronomy and former USDA wheat geneticist in Manhattan, currently senior scientist at The Land Institute in Salina. This is a slightly edited version of an article that first appeared in a recent online blog post on the Mother Earth News web site (Part 1 and Part 2), and is reproduced here with permission. – Steve Watson, Agronomy eUpdate Editor)
There are many health benefits to eating whole-wheat foods. But wheat isn’t good for everyone. Just under one percent of people in the United States suffer from an autoimmune condition called celiac disease, in which certain peptides — protein fragments produced during digestion of wheat's gluten proteins — severely damage the walls of the intestines. In addition, an estimated one-half percent are allergic to wheat, while a still-unknown number of Americans have a less well-defined condition often characterized as wheat sensitivity or gluten intolerance. It is universally recommended that people who have celiac disease, allergies, or a definitive diagnosis of gluten intolerance refrain from eating foods that contain grain from any type of wheat or from related species such as barley or rye.
As often happens with widely publicized medical conditions that affect a very small segment of the population, millions of additional people have become convinced in recent years that they also are gluten-intolerant when they are not. During the past two and a half years, a cloud of confusion has enveloped the issue of wheat’s impact on the human body. Much of the fog has been created by cardiologist William Davis and his bestselling 2011 book Wheat Belly: Lose the Wheat, Lose the Weight, and Find Your Path Back to Health. In the book and elsewhere, Davis recommends that everyone, including those who are free of any wheat-related medical condition, should adopt a wheat-free diet. He blames wheat consumption for causing a host of medical problems: gastrointestinal disruption, obesity, diabetes, autism, hyperactivity disorders, multiple sclerosis, rheumatoid arthritis, dementia, coronary artery disease, and even erectile dysfunction.
There has been other anti-wheat writing coming out — for example David Perlmutter’s more recent Grain Brain — but the wheat-free movement, which show no signs of ebbing (yet), was largely triggered by Wheat Belly. To support his claims, Davis cites evidence from his own practice, noting that patients whom he has put on wheat-free diets have lost weight while experiencing other health improvements. However, such anecdotal observations do not implicate wheat as the sole or even primary cause of those conditions.
Experts have pointed out that the symptoms that lead many people to a self-diagnosis of gluten intolerance can be caused by a wide range of factors unrelated to wheat, and that excluding wheat or any major ingredient or class of food from the diet usually does lead to lower total calorie consumption and weight loss. On the other hand, a 2010 report from the long-running Framingham [Massachusetts] Heart Study showed that subjects who adhered most closely to dietary guidelines that included five servings of grains per day—with whole wheat products prominent—achieved greater loss of belly fat than any other group.
In point-by-point reviews of Davis’s claims published by the Journal of Cereal Science and the American Association of Cereal Chemists’ journal Cereal Foods World, very little in Wheat Belly has stood up to scientific scrutiny; in particular, thorough examination of published research (some of it published in the years since Wheat Belly came out) has turned up little or no solid experimental evidence to support the notion that wheat is a top culprit in modern health problems.
Editor’s Note: The abstract from the article in the journal of Cereal Science, cited above, states:
“After earlier debates on the role of fat, high fructose corn syrup, and added sugar in the aetiology of obesity, it has recently been suggested that wheat consumption is involved. Suggestions have been made that wheat consumption has adverse effects on health by mechanisms related to addiction and overeating. We discuss these arguments and conclude that they cannot be substantiated. Moreover, we conclude that assigning the cause of obesity to one specific type of food or food component, rather than overconsumption and inactive lifestyle in general, is not correct. In fact, foods containing whole-wheat, which have been prepared in customary ways (such as baked or extruded), and eaten in recommended amounts, have been associated with significant reductions in risks for type 2 diabetes, heart disease, and a more favourable long term weight management. Nevertheless, individuals that have a genetic predisposition for developing celiac disease, or who are sensitive or allergic to wheat proteins, will benefit from avoiding wheat and other cereals that contain proteins related to gluten, including primitive wheat species (einkorn, emmer, spelt) and varieties, rye and barley. It is therefore important for these individuals that the food industry should develop a much wider spectrum of foods, based on crops that do not contain proteins related to gluten, such as teff, amaranth, oat, quinoa, and chia. Based on the available evidence, we conclude that whole-wheat consumption cannot be linked to increased prevalence of obesity in the general population.”
Nevertheless, growing numbers of Americans have become convinced that their health improves when they abstain from wheat. How much of that improvement is the result of a placebo effect similar to that associated with many medical treatments — a phenomenon “common in adults,” according to the University of Chicago Celiac Disease Center? A placebo-controlled experiment published by the American Journal of Gastroenterology in 2012 provides some clues.
The study, conducted in Italy, drew its subjects from a pool of 926 non-celiac patients who displayed the symptoms of irritable bowel syndrome and had received a diagnosis of wheat sensitivity. After four weeks of a diet that excluded wheat, cow’s milk, eggs, tomato, and chocolate, subjects embarked on a double-blind, placebo-controlled “crossover”-style experiment in which half of patients consumed a daily “dose” of wheat for two weeks and then for another two weeks consumed a placebo; meanwhile, the other group of subjects consumed the placebo for the first two weeks and wheat for the second. At the end of the trial, analysis of symptoms showed that only 30 percent of patients in either group had had a negative reaction to wheat; the other 70 percent, despite their previous diagnosis, were not actually wheat-sensitive.
Just as significantly, of the 276 patients who did react negatively to wheat, 206 turned out to have sensitivity to multiple foods, with “clinical features similar to those found in allergic patients.” The study showed that wheat sensitivity is a real medical condition for some people, but that fewer that 8 percent of subjects who had originally been diagnosed as wheat-sensitive actually reacted badly to wheat alone.
Davis also asserts that wheat proteins called gliadins, one class of gluten protein, act as an addictive drug, compelling us to overeat. He states, “Everybody ... is susceptible to the gliadin protein that is an opiate. This thing binds into the opiate receptors in your brain and in most people stimulates appetite, such that we consume 440 more calories per day, 365 days per year.” Davis's claim that gliadins are addictive is based on a 1979 finding that in cell cultures, certain peptide fragments from gliadins bound to the same receptor sites in the brain as did opium-derived drugs. Although Davis would have readers believe that these peptides, known as opioids (not “opiates”), are unique to wheat, the 1979 study also found that opioids from rice, spinach and milk also bound to those same receptors. These data were generated by treating cell cultures and rat organs directly with purified opioids; no research has been conducted in which people are examined for mental effects after consuming wheat.
There still is no evidence that when wheat foods are consumed and digested, that opioids are produced or absorbed or that they move through the bloodstream unaltered to the brain receptors in doses large enough to have an addictive effect or stimulate any particular behavior.
The manager of an organic flour mill told me recently that he is seeing huge demand among his customers for flour produced from the grain of a single variety: the heirloom hard red winter wheat Turkey Red. That popularity is good for his business, but he was curious about customers’ reason for seeking out Turkey Red flour. Some of them, it turns out, believe they are gluten intolerant and they claim that their symptoms go away when they eat only Turkey Red flour.
The miller, like anyone who works with wheat, is aware that the kernels of all varieties, including Turkey and other heirlooms, contain high concentrations of gluten proteins. The forms of gluten that are extremely hazardous to people suffering from celiac disease are present in all wheats, and there is no evidence that old-time wheat varieties like Turkey are any less likely than modern ones to hurt people who suffer from allergies or milder forms of gluten intolerance either.
Given the mass confusion over wheat and gluten that has arisen in recent years, it is very likely that the miller’s customers who see benefits when they switch to Turkey are experiencing the kind of placebo effect that I discussed earlier.
A rise in the diagnosis of celiac disease in particular has been attributed by some, including Davis, to an assumed increase in the human population’s exposure to certain partial digestion products of gluten proteins called “epitopes” that have been implicated in celiac disease. One of the known problem peptides, called Glia-α9, was examined in an oft-cited study done in the Netherlands. In it, the authors concluded that modern wheat varieties produce higher concentrations of Glia-α9 than do varieties from earlier in the twentieth century.
But on closer inspection, the results tell a different story. Grain from all 86 varieties in the study, modern and traditional, contained Glia-α9 and are therefore toxic to celiac patients. On average, the newer varieties contained an estimated 20 percent more Glia-α9 than did older varieties; however, that difference was not analyzed statistically in the paper. When you do a simple analysis, it shows that the 20 percent difference could easily be the result of mere chance. Indeed, there was wide variation among varieties within both the new and the old groups. And the highest level of Glia-α9 in the entire study was found in one of the old varieties.
Davis has said of modern wheat, “It’s an 18-inch tall plant created by genetic research in the '60s and '70s. This thing has many new features nobody told you about, such as there’s a new protein in this thing called gliadin. It’s not gluten.” Nothing in this statement is accurate. Modern wheats grow much taller than 18 inches unless they are under severe water or nutrient stress; the composition of the wheat kernel is unrelated to the plant’s height; gliadin proteins are not new to wheat; and gliadins really do belong to a larger category of proteins collectively known as “gluten.”
Robert Graybosch, a wheat geneticist with the U.S. Department of Agriculture in Lincoln, Nebraska, cites numerous studies spanning several decades and showing that all types of wheat new and old—including durum, spelt, emmer and einkorn—contain gliadin and glutenin proteins. And, he adds, “Gliadins and glutenins are highly variable. Every wheat plant contains many different genes encoding both types of protein. A given wheat plant may produce 100-plus gliadin molecules and 50 glutenin subunits.”
Any one of myriad gliadin and glutenin variants is very likely to be found in varieties up and down wheat’s family tree and even in barley and rye. As a result, all species and types of wheat are off-limits to celiac patients. But while wheat can also cause intestinal problems for that other small percentage of people who are non-celiac but gluten-intolerant, there is no evidence that it triggers celiac symptoms in anyone who doesn’t already have celiac disease.
Wheat kernels have contained gliadins for as long as there has been wheat. For example, two purportedly ancient wheat varieties, Kamut and Graziella Ra, have higher gliadin concentrations than modern wheats do, and other old-time wheats are also high in gliadins. According to Graybosch, “It probably is not speculation to say we could actually be consuming less gliadin than great-grandpa did.” And per-capita wheat flour consumption back in 1900, long before the rise in incidence of celiac disease, was 67 percent higher than today's average consumption.)
In his “Wheat Belly Blog,” Davis further states that although there is no transgenic (“genetically modified”) wheat on the market (that much is true), traditional wheat breeding is even more dangerous than transgenic technology: “By definition, hybridization, backcrossing, and mutation-inducing techniques are difficult to control, unpredictable, and generate plenty of unexpected results. In short, they are worse than genetic modification. Imagine we were to apply similar techniques of hybridization and mutagenesis to mammals–we’d have all manner of bizarre creatures and genetic freaks on our hands.”
The fact is, people have used hybridization and backcrossing for centuries as they have developed animal breeds and plant varieties. All crop and livestock improvements and nutritional changes brought about by breeding, from the dawn of agriculture to the present day, have resulted from farmers and plant breeders repeatedly interpollinating varieties or species to generate biologically diverse populations and selecting desired plants. And long before there was any plant breeding by humans (in fact, before there were modern humans at all), the evolutionary processes that led to wheat included periodic episodes of natural hybridization between different species. The result was an array of wheat species with chromosome numbers ranging from 14 to 42. As for mutations, they occur naturally all the time, while chemical- or radiation-induced mutation has contributed to the development of very, very few plant varieties.
Stan Cox, Adjunct Professor of Agronomy and Senior Scientist, The Land Institute, Salina