SAN FRANCISCO – Elimination diet crazes have been around for centuries, and one of today’s biggest targets is gluten, contributing to an industry of gluten-free products with revenue in the billions of dollars.
But does taking gluten off your child’s plate actually improve their health? It will if they have a condition in which gluten actually causes symptoms, explained Michelle M. Pietzak, MD, a pediatrician at the University of Southern California, Los Angeles.
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Gluten is a mixture of proteins found in wheat, rye, barley, oats, corn, and rice that gives food its elasticity and helps dough rise. Only the gluten in wheat, rye, and barley causes gluten-related symptoms, but it is found in a variety of derivative products, such as spelt, kamut, triticale, couscous, bulgar, faro, matzo flour, and other grains as well. Oats are also considered cross-contaminated with gluten because they are milled with wheat, and other foods containing gluten may be difficult to identify due to food labeling and preparation practices in the United States.
For those with celiac disease, wheat allergy, irritable bowel syndrome (IBS), or nonceliac gluten sensitivity or intolerance, a gluten-free diet can reduce or eliminate the symptoms causing problems. For others, however, the symptoms likely come from somewhere besides gluten or may be a nocebo effect, where a patient who expects negative symptoms becomes more likely to have them.
Lactose intolerance is one example that can cause symptoms similar to those that respond to restricting gluten. Another is sensitivity to fructans, a wheat carbohydrate and one of the fermentable oligo-di-monosaccharides and polyols (FODMAPs) that can improve IBS when restricted. Imbalance in a person’s gut bacteria, called dysbiosis, also may cause similar symptoms and results from excess yeast, parasites, or an overgrowth of bad bacteria in the absence of beneficial ones.
Understanding celiac disease
This immune-mediated disease causes primarily gastrointestinal symptoms when someone ingests proteins called prolamines, which those with celiac disease are genetically predisposed to have difficulty digesting. Common symptoms include diarrhea, nausea, vomiting, abdominal pain, constipation, appetite changes, and, in unusual cases, excess fat in the feces (steatorrhea).
But celiac disease also may contribute to a short stature, osteoporosis, dermatitis herpetiformis, delayed onset of puberty, infertility, anemia (from iron and/or folic acid deficits), epilepsy, and behavioral changes. Although those with celiac disease are at a higher risk for arthritis, osteoporosis, osteopenia, osteomalacia, and rickets, a gluten-free diet can improve children’s low bone mineral density.
Screening for celiac disease includes testing for antigliadin (AGA) IgG and IgA, antiendomysial IgA, anti-tissue transglutaminase (tTG) IgA, total serum IgA, and genetic testing related to HLA-DQ2 and HLA-DQ8 genes.
Wheat allergy
A wheat allergy, among the eight most common food allergies, involves an IgE-mediated reaction to water- and salt-insoluble gliadins, especially omega-5 gliadin, which can cause anaphylaxis in a wheat-allergic person who exercises after ingesting wheat. Symptoms of wheat allergy include hives; swelling, itching or irritation of the mouth, throat, eyes, and nose; difficulty breathing; and cramps, nausea, vomiting, and diarrhea. Wheat allergy most commonly occurs in infants or toddlers, and typically co-occurs with other food allergies, but children usually outgrow the allergy by ages 3-5 years.
Nonceliac gluten sensitivity or intolerance
Physicians only should consider gluten insensitivity or intolerance after ruling out celiac disease and wheat allergy. Less understood and more controversial, gluten sensitivity or intolerance may be an immune-mediated condition – or instead an intestinal malfunction. Some patients may simply have an intolerance to high fiber foods in general. Patients with this sensitivity or intolerance will have a normal intestinal biopsy, but AGA IgG and/or IgA testing and genetic HLA-DQ2 testing may be positive. The clinical diagnosis is ultimately one of exclusion determined when a gluten-free diet alleviates symptoms.
Although gas, diarrhea, weight loss, and abdominal pain are the most common symptoms, other transient symptoms may include dyspepsia, nausea, vomiting, bloating, constipation, intestinal rumbling, joint or bone pain, muscle cramps or pain, fatigue, numbness, cramps, headaches, rashes, tongue inflammation, anemia, leg numbness, osteoporosis, or unexplained anemia.
Another potential effect of gluten sensitivity is dermatitis herpetiformis, a skin inflammation involving blisters, hives, or other types of erythematous or urticarial papules, usually symmetrically distributed, with severe itching. Although 90% of individuals with dermatitis herpetiformis lack any gastrointestinal symptoms, about 75% have villous atrophy, Dr. Pietzak said.
Even less understood are neurologic symptoms of gluten sensitivity and their potential mechanisms. Reported neurologic findings of gluten sensitivity include ataxia, peripheral neuropathy, depression, schizophrenia, epilepsy, and intracranial calcifications.