In the February-March issue of MOTHER EARTH NEWS magazine, I discuss the health benefits of eating whole-wheat foods. But I also stress that 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 frenzy, 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.
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.
Flying in the face of published research, Davis also charges that wheat proteins called gliadins, one class of gluten protein, act as an addictive drug, compelling us to overeat. He claims, “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.
In my next post, I will examine recent claims that new wheat varieties have worse negative health effects than do older ones.
Photo by Fotolia.
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