Gluten: What's the Deal?

By Wendy Gordon

Several years ago, my daughter realized she could no longer tolerate wheat gluten. At the time, her condition was unusual, but she's gaining a lot of company these days. Half my book group won't eat my banana bread anymore. Gluten-free aisles in the supermarket and even whole gluten-free bakeries are sprouting like dandelions (at least here in Portland, Oregon). You'd think gluten was poison, rather than the magic elastic protein that turns pellets of grain into loaves of yeasty bread.

What's going on?

The peculiar aspect of a wheat-related allergy is that wheat is the most important grain source for humans, grown in regions as diverse as China, France and Australia. It has been cultivated domestically since at least 9,000 BCE and maybe much longer than that. Other gluten-bearing grains, such as barley, oats and rye, have been around for a long time as well. Cultivation of wild barley dates back to 23,000 BCE. Presumably, wheat would not have earned the term "staff of life" if it routinely made people ill.

In the U.S., wheat consumption rose rapidly until the beginning of the 20th century, driven by improvements in growing and milling techniques and the development of breakfast cereals. Consumption peaked in 1880 (at 225 pounds per capita) and then declined as people diversified their diets by adding more sugar, meat, eggs, milk, fruit and vegetables. In the 1960s, wheat consumption increased again as people sought to avoid excess fat and cholesterol. The booming popularity of fast foods also encouraged the rise. By 2000, the low carbohydrate fad took hold and wheat intake decline again, leveling off by 2007. The American population actually eats half the wheat now than it did in 1880, yet millions of people who suffer from their "wheat allergy" are not imagining their discomfort. Clearly the situation is more complicated than meets the eye.

One complexity often overlooked is the difference between celiac disease and wheat allergy. Celiac disease is a hereditary autoimmune disorder in which eating gluten leads to damage of the mucosae of the small intestine and a malabsorption of nutrients. While it is found worldwide, frequency varies depending upon ethnicity. For instance, one in 77 Swedish children suffer from celiac disease, while only one in 230 Italian children do; in Japan, the disease is virtually unknown. In the U.S., approximately one percent of the population suffers from CD. Specific genetic markers (HLADQ2/DQ8) are found in 95% of sufferers, but these genes are also found in 20 to 30% of the general population. Exposure to dietary gluten is by far the most potent trigger, but other environmental factors may play a role. People with juvenile diabetes, Down syndrome, Turner syndrome, rheumatoid arthritis and other autoimmune conditions have a higher incidence of CD. The degree of mucosal damage and subsequent symptoms varies greatly from person to person. Complete avoidance of dietary gluten is the only known treatment. It is effective, though: in the absence of gluten, the mucosae heal, symptoms disappear and people can live a normal life.

The immune system is terribly complicated and the etiology of celiac disease poorly understood. Most scientific research points to the involvement of the T cell system. Typically, CD manifests itself with gastrointestinal symptoms (diarrhea, bloating, abdominal pain). Depending on the extent of damage to the intestinal mucosae, any number of nutrient deficiencies may develop.

However, an increasing body of evidence points to cases where patients' intestinal mucosae are normal and the disease manifests itself neurologically. Gluten appears to damage the Purkinje cells of the cerebellum, causing ataxia (poor coordination) and perhaps contributing to autism, ADHD and schizophrenia. Sometimes the only symptoms are oral ulcers and collections of itchy blisters.

Wheat allergy differs from CD in several ways. While CD is a direct reaction to gluten, one can be allergic to several different proteins found in wheat, with the albumin and globulin fractions being most common. CD patients cannot tolerate any grains that contain gluten, including rye, oats, barley and spelt, while allergy sufferers may be able to eat these foods. The means by which the immune system mediates the response also differs, involving primarily IgE and mast cells. Allergy symptoms vary but generally include skin manifestations such as hives, eczema or tissue swelling. Sometimes nausea, asthma or rhinitis occur, but rarely do people suffer more severe reactions like anaphylactic shock. Reactions may become more severe with repeated exposure. Aerobic exercise can exacerbate reactions, as can aspirin, NSAIDs such as Advil and the additives MSG and sodium benzoate. Wheat allergies are among the eight most common food allergies, affecting up to six percent of children under three (it's less common in adults).

Diagnosis of celiac disease is difficult. While it's easy to pinpoint the genetic marker, most people with the marker do not develop the disease. An intestinal biopsy can provide a clear diagnosis, but a normal biopsy does not preclude CD. Commonly, celiac disease usually manifests itself by two years of age, but may not produce symptoms until adulthood. Reviewing one's family medical history provides clues; beyond that the only sensible method is to try a gluten-free diet and see if it alleviates symptoms. Allergies are even harder to diagnose, as the symptoms are so diffuse and vary greatly in intensity. Again, your best bet is to eliminate gluten from your diet and see if that helps.

This brings us to the second oft-overlooked complexity. We don't get our gluten (and other wheat proteins) from grains alone. Food processors often use enzymes to cut proteins into pieces, adding water to the cut sides. This creates what are called wheat protein hydrolysates, which expose buried antigenic sites in the proteins and cause allergic reactions that would not otherwise occur in their natural, whole states. Substances that include processed wheat proteins include maltodextrin, seitan, gelatinized starch, hydrolyzed vegetable protein, modified food starch, soy sauce, soybean paste, hoisin sauce, beta-glucans (vegetable starch) and vegetable gum. Since exposure increases symptoms in both CD and allergies, our amplified intake of these substances, along with excess use of medications such as aspirin and Advil, may very well be causing the increased prevalence of wheat intolerances.

It's a wise decision, when dealing with potential symptoms of either CD or allergy, to eliminate gluten and see if that solves the problem. And of course, this is yet another reason to eat whole, unprocessed foods. My only concern is that gluten intolerance is becoming an easy blanket diagnosis, crowding out other possible reasons for the same symptoms.

Meanwhile, I've got lots of leftover banana bread.

Wendy Gordon lives in Portland, Oregon, where she is a restaurant reviewer and freelance writer. She has an MS in Clinical Nutrition from the University of Chicago Medical School.