WHAT IS GLUTEN?
Gluten is a protein that is found in wheat and other grains, such as barley, kamut, and spelt. Gluten has an elastic and gluelike capacity that makes grain products chewy. Commonly consumed gluten-containing products include pasta, bread, pastries, croutons, and cereals. Gluten is a hidden ingredient in many food products on the market: soy sauce, pie fillings, foods that contain “hydrolyzed protein,” some canned foods, deli meats, beer, foods with sugar alcohols, sauces, and fast food. Gluten also may be found in preservatives, breading, and thickening agents.
For some people, eating GF is a choice. But for a growing number of people, eating GF is necessary. People for whom a GF diet is beneficial and even life-saving are those with celiac disease (CD), gluten intolerance (GI), and wheat allergy (WA). Although these types of sensitivities to gluten are different in their origins, they are treated the same way: a GF diet.
CD is not a food allergy. It is an autoimmune disorder in which the small intestine is hypersensitive to gluten. The digestive tract contains tiny hairlike projections called villi, where food is absorbed. These villi are destroyed in people with unmanaged CD. When the villi are not functioning properly, nutrient deficiencies will result because carbohydrates, fats, proteins, vitamins, and minerals, and even water in some instances, cannot be absorbed. In the athlete, the malabsorption also leads to decreased exercise performance (5,8).
Some symptoms of CD include diarrhea or constipation (or a combination of both), intestinal cramping, gas, pale fatty runny stools (steatorrhea), anemia, weight gain, or unexplained weight loss with an increased appetite. Weight gain has been a puzzling yet new observation. Once labeled a malabsorption syndrome, the hallmark of CD has been wasting. Today, many people with CD are normal weight or overweight.
CD affects not only the gut but also many other parts of the body and organs. The primary symptoms are listed in Table 1. Some people do not exhibit any symptoms until CD has become severe. Individuals often have CD for more than a decade before a diagnosis is made. True CD is a life-threatening condition and has been associated with many other disorders, such as leaky gut syndrome, hypothyroidism, type I diabetes, and other autoimmune diseases.
Once considered a rare disease, the prevalence of CD has increased dramatically during the last 100 years. Today, it is thought to affect 1% of the population (2). This disease is underdiagnosed, and this estimate is thought to be grossly underestimated. Because this disease is genetically based, first-degree relatives will have an increased risk of also being diagnosed with CD, as high as 1 in 22 (2). Diagnosis is based on a blood test. However, false-negatives are an issue. A combination of blood tests (i.e., testing for antibodies and tissue damage), genetic markers, and history is ideal. A tissue biopsy of the small intestine is the ultimate standard for CD diagnosis. Because the only treatment available for CD is a strict GF diet, a person may want to try a GF diet even if his or her test is negative. People who test negative at first may test positive years later. When undergoing testing, individuals who have been following a GF diet will yield negative results on blood tests and biopsies because the body will have had a chance to heal. For accurate testing for CD, the patient needs to eat gluten for several weeks before the test.
GI is very similar to CD. People with GI suffer similarly to people with CD but do not test positive for CD. Unlike CD, where the person can have no gluten in his or her diet from any source, people with GI exhibit a range of gluten sensitivity. Some may be able to eat small amounts of gluten until they reach a threshold, whereas others cannot tolerate any gluten. About 5% to 10% of the population may have some degree of GI, but higher estimates have also been reported (3). The reason for this dramatic rise (in both GI and CD) is unknown. Marion Nestle, author of Food Politics, claims that the higher prevalence is caused by more awareness of the disorder (hence, better diagnosis) (7).
Unfortunately, blood tests cannot be routinely used to diagnose GI. Individuals with GI may exhibit more than 100 documented symptoms associated with GI, and people do not react similarly. Some commonly seen symptoms that improve with a GF diet are included in Table 1. Gluten ataxia, one of the symptoms, is a relatively new concept that involves neurological dysfunction that exhibits itself as reduced coordination and muscle control (3). If an athlete has gluten ataxia, serious implications for sports performance may result.
GI often can be subtle and will worsen with continued gluten consumption over time. Continued consumption of gluten with true gluten sensitivity will contribute to further deterioration of the body and lead to a multitude of degenerative symptoms (i.e., osteoporosis). Because gluten sensitivity is an autoimmune response, continued consumption of gluten can manifest other autoimmune disorders.
The best way for people to determine if they are GI is to be evaluated and diagnosed by a gastrointestinal specialist and work with a registered dietitian on following an elimination diet. On this diet, a person completely eliminates all gluten and gluten-rich foods for several weeks and then slowly adds these foods back into the diet. Record keeping is essential to determine symptoms before and after the diet. Because this diet is quite difficult to follow, consultation with a registered dietitian is critical. The diagnosis of GI is still evolving and may also include testing for steatorrhea.
WA differs from GI and CD. People who have a WA have a systemic response to wheat similarly to how people with nut allergies may react. Symptoms of WAs are similar to symptoms of other allergies, namely, hives, swelling, and possibly stomach pain.
CONCERNS FOR THE ATHLETE, FITNESS PROFESSIONAL, AND ACTIVE INDIVIDUAL
Individuals who train strenuously and competitively need to plan their nutrition carefully for optimized athletic performance and decreased gastrointestinal symptoms. Quickly absorbing carbohydrates before, during, and after training are backed by years of scientific research to improve such performance (4). Many athletes are turning to the GF diet to reduce gastrointestinal symptoms. Anecdotal claims suggest that the GF diet also will reduce inflammation and improve performance. Unfortunately, these claims are testimonial based with limited research to support them. Athletes who improve performance with a GF diet may have undiagnosed CD or GI. They may improve their nutrient intake by switching to a GF diet, or they may lose weight, and thus feel and perform better. Therefore, a GF diet would naturally improve performance. More research is needed to prove or disprove this theory for people without CD or GI.
Although a low body mass index is considered to be a hallmark of CD, obesity in CD patients is higher than was suspected. For example, one study found that almost one half of CD patients are overweight at the time of diagnosis (9). Some preliminary research suggests that overweight people with CD lose weight when placed on a GF diet (1). Overcompensation for intestinal malabsorption is one explanation for this phenomenon. When the intestinal tract is damaged, nutrients cannot be absorbed, resulting in micronutrient deficiencies, which may drive food cravings (6).
The issues that arise from consuming a GF diet, however, also need to be addressed. GF diets are significantly more expensive than non-GF diets. Developing a healthy GF pantry can be quite challenging. Many GF products are energy dense but not necessarily nutrient dense. For example, in a regular box of crackers, the primary ingredient used is white flour. In GF crackers, the flours may include potato starch, rice flour, or other GF flours. These flours are processed and are more energy than nutrient dense. These products might be a good option during training, when rapidly absorbing carbohydrates are necessary. During the off season, these foods can become a source of excess energy. The type(s) of GF flour will determine the amount of fiber in the product. Athletes should check labels and focus on lower fiber options before, during, and after exercise training.
GF diets do not mean carbohydrate-free diets, a concept commonly confused. Whether an athlete is on a GF diet by choice or necessity, the proper amount of carbohydrates is needed to fuel training and competition. Many GF products available on the market consist of rapidly absorbed carbohydrates. Pastas and breads, typically recommended for intense training, contain high amounts of gluten. However, pasta and breads made from GF courses (i.e., rice, corn, quinoa) are available.
Many GF products are not enriched with vitamins and minerals as are conventional products. People on GF diets may be at risk for micronutrient deficiencies, although GF flours are naturally nutrient dense. Athletes may find it difficult to adhere to a strict GF diet, filled with wholesome GF grains, fruits, and vegetables, especially when traveling. In addition, these foods are high in fiber that may pose additional gastrointestinal issues during training. Athletes and active individuals need more assistance when planning a GF diet at home or on the road to prevent nutrient deficiencies. Supplementation may need to be a consideration.
DINING OUT GLUTEN-FREE
Athletes and active individuals may travel a great deal for competition or work. These individuals should be familiar with foods allowed on a GF diet. Table 2 summarizes foods to avoid, foods to carefully consider, and foods to consume when following a GF diet. Fortunately, many restaurants provide GF options. Extreme care should be noted because these menu items may not always be GF. Athletes and active individuals should be aware of hidden sources of gluten (i.e., soy sauce). Finally, in a restaurant, cross contamination is always a concern. The following points should be considered when dining:
* If the menu contains many breaded or fried foods, cross contamination may result. The cooks may not realize that cooking GF foods on equipment with gluten-rich foods will contaminate the food. For example, GF foods cooked in the same oven or grill station where gluten-rich foods were cooked could become contaminated. For example, is the chicken prepared on the same grill where the hamburger bun is toasted?
* Customers should call the restaurant and ask about the knowledge of the chef and kitchen staff with GF. Customers should be provided with a detailed answer about how the kitchen is prepared for GF recipes rather than general statements. If a consumer calls the restaurant and is not reassured with specifics about how GF menus are prepared, he or she should choose an alternative dining establishment.
* Choosing a restaurant that obtains foods from sustainable sources such as local/organic farms can help a customer feel safer when ordering GF foods. Conventional meat and farmed fish may have been fed grain (and gluten)-filled food, which may be problematic for some individuals.
The Gluten-Free Restaurant Awareness Program is a network that provides a resource of restaurants that serve GF menus following consistent guidelines (http://glutenfreerestaurants.org/). These tips, for a person with a true allergy, GI, or CD, may prevent extreme discomfort or a trip to the hospital.
THE GF PANTRY
Table 2 lists the foods that are GF (as well as those that are gluten-rich or have hidden gluten). Even when products should technically be GF, contamination with gluten may still be present (9). Individuals should choose simple wholesome foods or products with the “gluten-free” label. Checking ingredients, even of known products, may ensure that the product is truly GF. Because companies frequently change their formulations, something that was GF one year may not be GF the next.
Oats are one product that may or may not be safe for individuals following a GF diet. Oats should not contain any gluten but are typically manufactured in plants where cross contamination occurs. If oatmeal is commonly purchased, individuals should look for a label that specifically states that the product was processed without cross contamination. The label should say “gluten-free” as opposed to “wheat-free.” Although this should be a safer alternative to people with GI, people with diagnosed CD still need to be careful. Because oats contain a protein that is similar in structure to gluten, some people with CD can still react to oats, even if they are certified GF.
Spelt is an ancient grain that also contains gluten. However, spelt contains less gluten than other gluten-rich products and is nutritionally superior (more protein, fiber, and other nutrients) than wheat. Although a person with CD and WAs should not consume spelt, some people with lesser degrees of GI can safely experiment with this highly nutritious grain.
Finally, to avoid cross contamination at home, a designated GF toaster is advised. When baking, GF foods should be baked before gluten-filled foods and then the oven should be cleaned. Everyday household chores also need to be carefully reviewed. For example, many dishwashing gloves are coated with wheat-based flour. The glue in stamps and envelopes also may contain gluten, as do many cosmetics, art supplies, sunscreens, lotions, soaps, detergents, medicines, and supplements. For a complete safe list, go to www.celiac.com.
Health and fitness professionals may encounter clients who inquire about GF diets, their health effects, and whether eating GF may be a good choice for them. Many individuals experience GI symptoms but are not diagnosed with GI or CD. If symptomatic, the best referral a health and fitness professional may give to the client is to a medical professional to confirm a possible issue. However, the client may remain undiagnosed because of limitations of the tests. If the client is symptomatic but not diagnosed or is nonsymptomatic but is interested in trying a GF diet, it is important to inform them about the fact that GF diets also may be low in carbohydrate and can affect performance and recovery. In addition, GF diets may be low in micronutrients, resulting in deficiency. The best guidance for a serious exerciser with or without GI symptoms and interested in trying a GF diet would be provided by a nutrition professional (http://www.eartight.org/programs/rdfinder/). This is especially true if the client wants to learn more about GF grains, starchy vegetables (they are always GF), and other creative ways of integrating GF foods into a wholesome and athletically sound diet.
CONDENSED VERSION AND BOTTOM LINE
The prevalence of celiac disease (CD) has increased significantly. Concomitantly, the gluten-free (GF) diet has become a popular approach to eating. A strict GF diet for athletes who have CD, wheat allergy, or gluten intolerance will improve health and may enhance performance. Athletes with suspect gastrointestinal symptoms, fatigue, or skin rash should seek evaluation and consult with a sport dietitian. Athletes with gluten restrictions (by choice or need) can train safely, confidently, and productively. However, research has not examined how GF diets may impact the athletic performance of athletes or active individuals who choose GF eating plans.
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2. Fasano A, Berti I, Gerarduzzi T, 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: 286–92.
3. Hadjivassiliou M, Sanders DS, Grunewald RA, Woodroofe N, Boscolo S, Aeschlimann D. Gluten sensitivity: From gut to brain. Lancet Neurol. 2010; 9: 318–30.
5. Martin S. Against the grain: An overview of celiac disease. J Am Acad Nurse Pract. 2008; 20: 243–50.
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10. Venkatasubramani N, Telega G, Werlin SL. Obesity in pediatric celiac disease. J Pediatr Gastroenterol Nutr. 2010; 51 (3): 295–7.
Recommended Readings and Resources
Case S. Gluten-Free Diet: A Comprehensive Resource Guide. 4th ed. Canada: Case Nutrition Consulting; 2010.
Keywords:© 2013 American College of Sports Medicine
Celiac Disease; Gluten Intolerance; Wheat; Ingredients; Carbohydrate