Gluten-free foods are occupying more space on store shelves. Stores are offering gluten-free bread, breakfast cereals, pasta, and snacks. One store was selling gluten-free breaded pork chops. (Meat does not contain gluten; it was the breading that was gluten-free.)
In the U.S, about 3 million people – fewer than 1 percent of the population – have celiac disorder, also called sprue or gluten intolerance. People with celiac disorder cannot digest or metabolize gluten.
In these people, gluten passes through the stomach and into the intestine, where it causes an immune response. The immune response can take the form of diarrhea, constipation, bloating, abdominal pain, decreased appetite, hair loss, itchy skin, mouth lesions, nose bleeds, and other health problems.
Celiac disorder patients also may notice foul-smelling or fatty stools due to nutrient malabsorption. The end result is a substantial decrease in nutrient absorption because of damage to the intestine.
Celiac disorder occurs in children and adults. It is not gender specific. It is, however, more common in people with auto-immune diseases, such as rheumatoid arthritis, Down syndrome, lactose intolerance, thyroid disease, and type I diabetes.
Celiacs cannot consume foods containing gluten, regardless of whether the gluten is naturally present or an added ingredient. People with celiac disorder may be challenged to find gluten-free foods. Because up to 75 percent of the protein in grain is gluten, it is nearly impossible, with current technology, to remove or destroy all of the gluten in products containing barley, rye, oats or wheat (BROW).
Cooking or storage does not reduce the gluten content in BROW foods. A product labeled “gluten-free” may legally contain gluten. The Food and Drug Administration allows foods labeled “gluten-free” to contain 20 parts of gluten per million units of product. The 20 ppm – 0.002 percent – limit is the lower limit of the accuracy of the gluten testing procedure.
Also, the FDA classifies gluten as “generally recognized as safe,” so processors are not legally required to list the gluten content of a food on the label.
People who do not have celiac disorder have reported health benefits from a gluten-free diet, including marked weight loss. Nutritionists say the weight loss is due to the lifestyle change associated with a gluten-free diet regimen, however.
For example, a gluten-free diet emphasizes consumption of fresh fruits and vegetables and discourages eating fried food.
A group of Finnish researchers, including scientists from the University of Helsinki, reported that a gluten-free diet benefited patients with mild forms of gluten intolerance. Benefits included less damage to the small intestine. Patients fed gluten-free diets had less atrophy of villi, the part of the intestine where nutrient absorption occurs. Atrophy of the villi reduces nutrient absorption.
In the digestive tract, gluten is viscous and sticky. Scientists have shown that gluten traps minerals, protein, and other nutrients, inhibiting their absorption and making them unavailable to the animal. Gluten is also likely to inhibit nutrient uptake in humans, too.
The typical American diet contains excess nutrients, though, so nutrient deficiencies due to gluten should not be an issue.
Dr. Mark Haub, a nutritionist at Kansas State University, does not believe the hype about the health benefits of a gluten-free diet for people who do not have celiac disorder.
“People have been eating wheat, rye and barley for thousands of years, and there are people who live to be 100 who eat wheat products and don’t seem to exhibit any types of health issues,” he said.
As for using gluten-free diets to lose weight?
“The gluten-free product likely contains as many calories as gluten options,” Haub said. “A gram of sorghum, corn or rice flour appears to be metabolically similar to a gram of wheat flour.”
What is gluten?
Gluten is a protein that has a physiological function in grain. In a grain kernel, gluten serves as a storage protein; it provides protein to the developing plant embryo during germination. As seed germination progresses, the embryo uses gluten protein to form various plant tissues and structures, such as roots, stems, and leaves as well as hormones and metabolic signals.
Gluten is actually a combination of several proteins. The two present in the greatest concentrations are gliadin and glutelin. In addition to these proteins, the gluten complex also includes more than 50 other proteins – each present in low concentrations.
According to anthropologists, early humans abandoned the growing and eating of barley in favor of growing wheat because they preferred the “stretchy” texture of dough made from wheat. Dough made from wheat was stretchy because it contained a higher gluten content than did barley or rye.
The kernels of different species of grain contain different amounts of gluten. An easy way to remember which grains contain gluten is through the acronym BROW – barley, rye, oats, and wheat. Gluten is also present in triticale, a grain that is a cross between wheat and rye.
Oats are complicated. The main gluten in oats is avenin. Although avenin is a gluten, avenin does not cause the problems that wheat, rye, or barley glutens cause in people with celiac disorder. Also, oats are harvested, stored, and processed with the same equipment used to harvest, store, and process BROW grains. Therefore, oat products may become contaminated with gluten from other grains.
Likewise, flaxseed does not naturally contain gluten. However, as with oats, if flaxseed is processed with the same equipment as wheat, rye, or barley, cross-contamination can occur.
Corn and rice are grains. However, the gluten they contain is different from gluten found in BROW grains. Despite its name, buckwheat is not a grain. Instead, it is genetically related to rhubarb, and therefore, it does not contain gluten. Sorghum, soybeans, and canola do not contain gluten.
BROW products, particularly wheat flour, contain less than 15 percent gluten and the gluten content is highly variable. Wheat contains more gluten than rye or barley. For example, bread flour contains 9 percent to 13 percent gluten and all-purpose wheat flour contains 9 percent to 12 percent gluten. Barley flour contains much less gluten than does wheat flour – 4.5 percent to 5 percent gluten in barley. However, more than 500 varieties of barley exist. Therefore, a sample of barley may contain more or less gluten than the range mentioned above. Rye flour contains less gluten than barley flour contains.
In bread dough, the stretchy – or elastic – property of wet gluten enables it to trap carbon dioxide gas produced by the yeast that has been added to the dough. Trapped carbon dioxide is what causes bread to rise. Because wheat contains more gluten, bread made from wheat flour is “fluffier,” or lighter, than bread made from rye or barley flour.
Conversely, rye and barley bread are “heavier,” or denser, than wheat bread because of the lower gluten content in rye and barley.
For people with celiac disorder, a gluten-free diet is necessary for good health. However, there is little evidence that a gluten-free diet will benefit the health of non-celiacs.
Dom Castaldo, Ph.D., is a nutritionist and a biology instructor at Sauk Valley Community College in Dixon. He welcomes comments at firstname.lastname@example.org.