By: Alex M. McDonald, MD
Medical Doctor and Professional Triathlete
What is gluten?
Gluten is comprised of two proteins, gliadin and glutenin, which are found in the endosperm of grains such as wheat, rye, and barley. Gluten is the protein that nourishes wheat during germination from seed to plant. The stored proteins of maize and rice are sometimes called glutens, but they do not contain glutenin. True gluten — gliadin and glutenin — is limited to certain members of the grass family. Oats are naturally free of gluten, but many oat products contain gluten due to cross-contamination that arises from agricultural practices such as crop rotation, common or shared use of containers used to silo and then transport grains from fields to food facilities for packaging, etc. As a result, many people on a gluten-free diet are able to consume oats only from sources that keep cross-contamination with gluten to an absolute minimum and/or specifically sort out the oats to remove as much non-oat grain as possible.
There is a small sub-group of gluten-sensitive people — estimated at less than 1% of people with celiac disease — who are also sensitive to oats. Oats contain a type of prolamin known as “avenin” (similar in structure to the prolamin “gliadin” found in wheat) which has been associated with adverse health effects in people with celiac disease.
The glutenin in wheat flour gives dough its elasticity, allows leavening, and contributes to the chewiness of baked goods.
Wheat supplies a large percentage of the world’s food supply and dietary protein intake. Some goods are even fortified with gluten to provide more protein.
It has been discovered that gliadin plays a role in protecting the wheat seed from being digested by insects or animals before the seed can germinate. Some studies have shown that gliadin inhibits certain digestive enzymes in insects and causes intestinal disease in very young rodents. Therefore, research suggests wheat may have a natural tendency to cause gastrointestinal problems in humans, as well. One conclusion of studies on the subject is that gluten sensitivity may also be linked to other physical ailments. The rise in diagnoses of gluten sensitivity, particularly in adults, may reflect the convergence of many elements, including better awareness and detection of disease, the prevalence of wheat in the western diet, and an aging population that may be more susceptible to metabolic disorders.
Gluten-sensitive enteropathy: Celiac disease
Gluten-sensitive enteropathy (GSE), also known as celiac disease or celiac sprue, affects 1 in every 3,000 people in the U.S. Many in the medical community believe this condition is actually underdiagnosed, and that an estimated 1% of Americans (1 in 100 people) may have GSE but are not aware of their condition. GSE spans a broad spectrum of disease, from completely asymptomatic to highly symptomatic. The pathology behind the range of GSE diagnoses is the same, but the presentation of symptoms depends on the individual’s reaction and response to gluten.
GSE manifests when the body’s immune system identifies gliadin (one of the proteins of gluten) as a foreign invader and mounts an inflammatory immune response. This immune response causes damage to the intestinal mucosa (lining of the gut) and results in malabsorption and the inability to digest all food nutrients, not just gluten. Patients with celiac disease, the more severe end of the GSE spectrum, can have chronic diarrhea, fatigue, anemia, and unexplained weight loss; infants and children may not gain weight or grow properly. However, because some patients may have mild symptoms (atypical celiac disease) or no symptoms at all (silent celiac disease), GSE is thought to be underreported and underdiagnosed.
Widely recognized in Europe, GSE/celiac disease may be misdiagnosed by doctors in the US, because its wide variety of symptoms can be mistaken for many other illnesses. What was once believed to be a rare disorder primarily afflicting children is now estimated to affect up to 3 million Americans, many of whom are as yet undiagnosed. “There is underdiagnosis, mainly because physicians don’t consider the diagnosis,” says Dr. Peter Green, director of the Celiac Disease Center at Columbia University Medical Center. He estimates that the condition is undiagnosed in 97 percent of those who have it. “When it’s considered,” he says, “the next steps are easy: a blood test and, if that’s positive, a biopsy. It’s not considered, because the symptoms are diverse and, in some cases, mild.”
GSE can present a range of symptoms or none at all, but the more severe cases of celiac disease can include one or more of the following:
- Chronic diarrhea
- Steatorrhea (excess fat in the stool)
- Abdominal bloating or cramps
- Weight loss
- Bleeding disorders
- Seizure disorders
- Stunted growth
Although the disease is typically not fatal, patients with GSE, specifically people with celiac sprue, are at increased risk for medical conditions such as lymphomas and certain cancers of the intestinal tract. Untreated pregnant women are at higher risk for miscarriage and birth defects. Stunted growth due to poor nutrient absorption can result when celiac sprue is untreated during critical growth and development periods.
Genetics play an important role in GSE/celiac disease. The incidence of GSE in relatives of patients diagnosed with the disease is 10%, significantly higher than in the general population. However, there seem to be other factors at play, as well. In studies of identical twins where one twin has celiac disease, the other twin is found to have the disease only 75% of the time. This indicates a strong genetic component, yet does not fully explain the cause of celiac disease; environmental factors also may be at play.
The only effective treatment for moderate to severe GSE is a lifelong gluten-free diet. After gluten has been removed from the diet, the inflammatory response in the bowel wall subsides, and normal bowel function resumes, usually within a few months. Most patients respond very well, and can live perfectly normal lives.
Gluten sensitivity versus gluten-sensitive enteropathy
The term “gluten sensitivity” (GS) spans a wide variety of medical conditions in which gluten causes an adverse reaction. There is usually a more specific underlying cause for the symptoms, which should be investigated. The broad category of GS includes the full spectrum of GSE, which encompasses the general wheat allergy category, as well as severe celiac disease. Like celiac disease, a wheat allergy will trigger activation of the immune system; however, GSE and a wheat allergy produce quite different results: A wheat allergy will result in systemic (full body) anaphylaxis, whereas GSE is a long-term, slower immune response that eventually causes local intestinal damage.
A GS diagnosis is appropriate when GSE is likely, based on other coexisting conditions, but has not been fully established. The diagnosis of GS may also be used in ambiguous situations when other conditions may be present, or when diagnostic testing has not or can not be performed. However, the gluten-sensitive designation may not be appropriate in all cases. Almost always, a more specific cause can and should be identified to maximize treatment benefits. For example, if a person has a known wheat allergy that results in anaphylaxis — a sudden, life-threatening allergic reaction — this is not simply GS; it is a wheat allergy. Wheat allergies may be reactions to albumins or globulins of wheat, or the individual may have sensitivity to proteins commonly found in wheat products (e.g. fungal amylase or different yeasts). Therefore, diagnostic evaluation and follow-up is preferred to try to identify, as specifically as possible, an individual’s intolerance to wheat, gluten, or an associated substance. The relationship between gluten, as well as related compounds in and associated with wheat, to the various immunologic sensitivities these substances produce, is highly complex and not fully understood.
Challenges of a gluten-free diet
Following a gluten-free diet means giving up bread, pizza, pastries, pasta, and many processed and packaged foods. For an American living with the condition, it’s tough to navigate a wheat-filled world. People in other countries have it easier: Awareness of wheat allergies and celiac disease is more widespread outside the United States. “You can get a gluten-free Big Mac in Helsinki,” according to Dr. Green. “You can get a gluten-free pizza anywhere in Australia.”
A gluten-free diet requires the elimination of all forms of wheat, barley, and rye and their derivatives, which can be very difficult. Dining out can be a nightmare for those trying to avoid gluten. Aside from avoiding gluten, there can be other challenges associated with this diet. A diet without gluten may be lacking in certain vitamins and minerals (particularly B vitamins, fiber, and calcium). As a result, it is important to make sure these nutrients are obtained, and supplemented, if necessary. Comprehensive dietary education and follow-up from an experienced registered dietitian is an important element in the successful management of celiac disease and/or a gluten-free diet.
Grocery stores carry a variety of foods that are naturally gluten-free, such as fresh fruits and vegetables, meats, poultry, fish, and dairy products; on the contrary, a variety of packaged foods may be made with gluten-containing ingredients. To adhere to a gluten-free diet, one must become adept in reading labels and contacting food manufacturers if more information on the origin of ingredients is needed. It is also important be aware that products labeled “wheat-free” are not necessarily gluten-free.
Due to the growing demand in the US for gluten-free foods, a number of companies and stores have begun to offer a wide variety of gluten-free alternatives to more traditional foods, such as corn-, nut-, and rice-flour pastas, breads, cereals, and snacks. In some areas, it is even possible to find gluten-free bakeries. It is certainly easier to adhere to a gluten-free diet now than it was in the past!
On January 1, 2006, The Food Allergen Labeling and Consumer Protection Act (FALCPA) took effect. This requires food labels to clearly identify wheat and other common food allergens in the list of ingredients. FALCPA also required the U.S. Food and Drug Administration to develop and finalize rules for the use of the term “gluten free” on product labels. FDA proposed the rules on January 23, 2007, and these are close to being formally finalized.
Is gluten-free an emerging fad diet?
Considering the difficulty of being truly gluten-free, it is surprising the number of consumers that choose to go gluten-free, without having the symptoms or diagnoses of GS, GSE, or wheat allergy. While experts estimate the prevalence to be about 1% of the population, a recent survey estimated that 15–20 percent of consumers want gluten-free products.
Several problems with self-restriction without diagnosis exist, particularly for athletes. The grain products that are excluded on this diet are also excellent sources of carbohydrates, the primary fuel for your muscles. They also provide key nutrients, such as B vitamins, fiber, and iron. By being too restrictive in food intake, the athlete may fall short of taking in adequate calories to support their activity, and the added expense of such products can put a good dent in the budget. If someone self-treats, without seeking medical help, they may actually have a different condition that requires medical attention, which is then lacking the appropriate treatment. All these scenarios can negatively impact athletic performance.
Gluten-free for health and sports
Athletes who subscribe for whatever reason to a gluten-free diet may worry about obtaining enough carbohydrates in their diet to fuel themselves during periods of rigorous training. After all, carbohydrates are essential for maintaining energy levels during training and speeding recovery afterward.
Consuming enough carbohydrates to meet athletic requirements is possible on a gluten-free diet. You can choose from rice, gluten-free cereals and breads, white and sweet potatoes, bananas and other fresh fruit, vegetables, and gluten-free grains. Gluten-free flours, such as corn, rice, arrowroot, potato, and soy can be used to make breads and pastas. Tapioca, amaranth, quinoa, and corn meal are also acceptable starches for a gluten-free diet. It is important to work with a registered dietitian in developing a meal plan to help identify the usual carbohydrate sources and make appropriate gluten-free substitutions. This will ensure that you’re getting adequate nutrition, as well as enough carbohydrates to support your activity level.
Also, some athletes feel that avoiding gluten the few days leading up to a race or major event helps to decrease the risk of gastrointestinal upset during the event. However, keep in mind that this is simply based on individuals’ experiences.
Below is a list of some gluten-containing products and their gluten-free substitutes:
|Gluten-Containing Product||Gluten-Free Substitute|
|Semolina or durum wheat pasta||Rice, corn, or quinoa pasta|
|Udon noodles||Rice noodles, some soba noodles|
|Soy sauce||Wheat-free tamari|
|Worcestershire sauce||Bragg’s Liquid Aminos|
|Seitan (“wheat meat”)||Tempeh or baked tofu|
|Bulgur (in tabouleh, salads, and some chilis)||Quinoa|
|Couscous||Quinoa or millet|
|Wheat or wheat bran cereals||Grits, oatmeal or oatmeal bran
free of gluten cross contact
|Flour tortillas||Corn tortillas with gluten-free
|Baked goods made with wheat flour||Baked goods made with Quinoa
flour, rice flour, soy flour, or bean flour
|Flour for frying||Rice flour or corn meal for frying|
|Flour for thickening soups||Arrowroot, potato starch, or
cornstarch for thickening soups
Should I go gluten-free?
Due to the broad spectrum of symptoms that GSE can cause, it is a highly individual decision whether to adhere to a gluten-free diet. It is a choice that should be made in consultation with a physician and/or registered dietitian: If a person notices that they have symptoms while consuming gluten products or have had digestive problems, then further evaluation by a health care provider may be appropriate. Since symptoms of GSE and GS can be very subtle and are not necessarily limited to the digestive tract, it can be very difficult to determine a medical need for a gluten-free diet without professional help.
If you suspect you have GSE or GS, further testing by a medical professional can be used to confirm diagnosis. You are likely to have the condition if specific antibodies are detected in a simple blood test. A tiny tissue sample of the small intestine is used to confirm the diagnosis. Before being tested, one should continue to eat a diet that includes foods with gluten, such as breads and pastas. If a person stops eating foods with gluten before being tested, the results may be negative for celiac disease even if the disease is present.
Gluten: the bottom line
With the increasing awareness of gluten-sensitive enteropathy (GSE) and, more specifically, the term “celiac disease,” gluten has become a hot topic. Conventional, as well as specialty, health food stores are providing more and more gluten-free alternatives for those unable or unwilling to consume gluten. If a person suspects they have a medical condition or symptom that’s somehow related to gluten, they should discuss options with their physician and consult a registered dietitian prior to adopting a gluten-free lifestyle. However, unless a person has been diagnosed with GS or GSE, there is little scientific evidence to support that removing gluten from the diet is more healthful than a conventional, nutrient-dense, well-balanced diet.
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Fasano, A., Berti, I., et. al., Prevalence of Celiac Disease in At-Risk and Not-At-Risk Groups in the United States, A Large Multicenter Study; Arch Intern Med. 2003;163:286–292.
Greco L, Romino R, Coto I, et al. The first large population based twin study of celiac disease. Gut. May 2002;50(5):624–8.
Interview Dr. Peter Green, director of the Celiac Disease Center at Columbia University Medical Center.
Troncone R, Auricchio R, Granata V. Issues related to gluten-free diet in celiac disease. Curr Opin Clin Nutr Metab Care. 2008 May;11(3):329–33.
Celiac Sprue Association, http://www.csaceliacs.org/
The Gluten-Free Diet: An Update for Health Professionals http://www.healthsystem.virginia.edu/internet/digestive-health/nutritionarticles/sept0601.pdf