A strenuous endurance workout demands careful nutrition planning to optimize athletic performance and minimize the gastrointestinal (GI) distress – cramps, bloating, abdominal pain, and generalized fatigue – that plagues many recreational and elite athletes. In an effort to avoid these unpleasant GI symptoms, many athletes have experimented with adopting a gluten-free diet. With scientific evidence lacking, the success (or not) of a gluten-free diet in improving athletic performance is theoretical and anecdotal. Nonetheless, if you are contemplating going gluten-free because you’ve heard it will improve your performance, first make sure that you understand the implications.
Historically (and scientifically) a gluten-free diet only has been considered necessary for people with a relatively rare, but debilitating disease known as celiac disease. Celiac disease affects almost one percent of the population and is characterized by an allergic response to gluten-containing foods. Gluten is a protein compound made up of two proteins called gliadin and glutenin that are found joined with starch in the grains wheat, rye and barley. Exposure to gliadin – the “toxic” component of gluten for people with celiac disease—causes the body to go into immunologic overdrive. One of the consequences is decreased nutrient absorption. When the gut is unable to absorb nutrients, anemia, weight loss, abdominal pain, bloating, diarrhea and vitamin deficiencies may occur. The only definitive treatment for celiac disease is strict avoidance of gluten-containing foods.
Practical Tips to Prepare the Gut for Competition
- Get fit and acclimatized to heat
- Stay hydrated
- Practice drinking during training to improve race-day comfort
- Avoid over-nutrition before and during exercise
- Avoid high-energy, hypertonic food and drinks before (within 30-60min) and after exercise.
- Limit protein and fat intake before exercise.
- Ingest a high-energy, high-carbohydrate diet
- Avoid high-fiber foods before exercise
- Limit nonsteroidal anti-inflammatory drugs, alcohol, caffeine, antibiotics, and nutritional supplements before and during exercise. Experiment during training to identify your triggers.
- Urinate and defecate prior to exercise
- Consult a physician if GI problems persist, especially abdominal pain, diarrhea, or bloody stool
Originally from Brouns F, Beckers E (1993). Is the gut an athletic organ? Sports Medicine, 15, 242-257. Cited in Murray R (2006). Training the gut for competition. Current Sports Medicine Reports, 5, 161-164.
Over the past several years, a growing number of people without diagnosed celiac disease have experimented with gluten-free diets. In some cases, people have adopted the diet in simple protest against the current American culture of overconsumption of heavily processed, nutritionally-poor foods as many fresh, wholesome foods like fruits and vegetables are gluten free. Other people report that symptoms like tiredness, abdominal pain and diarrhea or constipation are decreased after adopting a gluten-free diet. These people are said to have “gluten sensitivity.” Gluten sensitivity is much more common, and less understood than celiac disease. It occurs when the body has a pronounced response to gluten-containing foods; it is not exactly clear what causes the symptoms or the body’s actual response to the gluten. Anyone with gluten sensitivity should be tested for celiac disease before adopting a gluten-free diet. (Tests done after gluten has already been eliminated from the diet are unreliable.)
Whether or not adopting a gluten-free diet affects athletic performance hasn’t been adequately studied to draw any concrete conclusions. Each athlete must weigh what is known about eating for optimal athletic performance with their individual experiences and discomforts during strenuous training. For example, many of the best sources of carbohydrate, the body’s preferred energy source during intense exercise, contain gluten. Thus, anyone who adopts a gluten-free diet needs to be especially careful to make sure to eat enough gluten-free carbohydrates to fuel the exercise session. (The American Dietetic Association recommends about 30-60 grams of rapidly-absorbed carbohydrate per hour of intense activity.) Fortunately, there are many high-carbohydrate, gluten-free foods to choose from including rice, corn, soy, potato, tapioca, beans, quinoa, millet, buckwheat, flax, nut flours and uncontaminated oats. Other inherently gluten-free products include milk, butter, cheese, fruits and vegetables, meat, fish, poultry, eggs, beans and seeds.
If an athlete experiences GI symptoms during an endurance session, it is important to investigate other potential culprits in addition to (or instead of) gluten. For example, many high-carbohydrate products have large amounts of fiber. While fiber is a nutrient that most people need to eat a lot more of for optimal health, it is also a source of GI discomfort when consumed with or soon before strenuous exercise. Check out the sidebar for tips on how to minimize GI distress during exercise.
Ultimately, a conscientious and nutrition-savvy athlete could successfully adopt a gluten-free eating plan to meet nutritional needs. It may be helpful to think of a gluten-free diet the same way you might think of a vegan diet -- because the diet is highly restrictive, people who adhere to the eating plan face many potential nutrient deficits which could be detrimental to athletic performance. However, with appropriate planning, both vegan and gluten-free athletes can consume a balanced and complete diet that prepares them for peak performance. A registered dietitian with a focus on sports nutrition can help you adopt a well-designed and individualized gluten-free eating plan to fuel optimal health and athletic performance.
While gluten can be poison for a person with celiac disease, for most everyone else gluten itself is not inherently unhealthy. Perhaps the best way for many people who do not have celiac disease to feel better, adopt an overall healthier way of life and achieve athletic gains is to continue to focus on minimally-processed foods (gluten free or not), eat a diet rich in wholesome foods like fruits and vegetables, and adequately prepare the gut for competition.
By Natalie Digate Muth
Natalie Digate Muth, MD, MPH, RD, FAAPNatalie Digate Muth, MD, MPH, RD, FAAP is the Healthcare Solutions Director for the American Council on Exercise, a board-certified pediatrician and Fellow of the American Academy of Pediatrics, a Diplomat of the American Board of Obesity Medicine, registered dietitian and board-certified specialist in sports dietetics, and ACE-certified health coach. She is the author of "Eat Your Vegetables" and Other Mistakes Parents Make: Redefining How to Raise Healthy Eaters" and the upcoming textbook "Sports Nutrition for Health Professionals". She has been ACE certified since 1998.
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