Photo: CC--Carine06 08/09/2016 - Is athletic improvement, after beginning a gluten-free diet, a sign that the athlete had gluten intolerance or celiac disease? Or, could it simply be a benefit of following a gluten-free diet?
The real cause of the gluten-free athlete's improved athletic performance may be harder to uncover than you think. Could the serious athlete's diet, free from gliadin and glutenin (the two protein groups found in wheat, barley, rye and triticale which create what we collectively label as "gluten"), cause improved physical output? Or, is it possible that these high-performing machines we call athletes may have had an undiscovered intolerance to the gluten substance before they ever discovered the diet?

The "cause and effect" here may be hard to define; or, quite possibly, impossible.
Most data now supports that as many as 10% of people may have negative reactions, or an intolerance to, the gluten found in wheat, barley and rye products and by-products(1). However, most people may not even realize they have symptoms, and like many of us, chalk them up to numerous other issues: I worked out too much. I have a sensitive stomach. I ate something bad. It's too hot out to digest properly… and, of course, the list goes on.

If a marathon runner, soccer player, football player, Olympic athlete, or anyone else who trains recreationally, semi-professionally, or professionally, were to have some level of intolerance and remove gluten from their diet, it is very likely they would see a marked improvement in their performance. This boost in athleticism could be credited to a number of factors including increased and improved absorption of vital nutrients such as iron, calcium, and vitamin D as well as secondary nutrients such as B12, copper, folate, magnesium, niacin, riboflavin and zinc. Athletic improvement can also be attributed to better overall awareness and tracking of what is being consumed. (This better management and awareness generally leads most athletes to eat cleaner, less refined and less processed foods as a result.)

On the flip side, the reverse is also true: Athletes might be seeing better performance results… even if they are not intolerant to gluten or have celiac disease. The improved performance may, in fact, be a product of increased protein intake (which tends to happen when processed carbohydrates are removed from the diet), better overall decision-making (like choosing whole foods or "clean" foods in order to avoid gluten), as well as higher natural fiber intake (from beans, vegetables, and whole grains such as quinoa, rice, and even amaranth) which aid the body's systems and digestion. The foods that performance and endurance athletes eat on a strict gluten-free diet are less likely to have been processed, and therefore low in salt, low in chemicals, and anti-inflammatory. (Thus, making it easier to train harder, faster, and longer.)

As you can see, it's a real "what came first.. chicken or the egg" dilemma. Both groups, both gluten intolerant and non-intolerant athletes could be showing improvement on a gluten-free diet. So how do you know if the athlete has an intolerance that led to the improvement?

In a landmark study, conducted by the University of Chicago Celiac Disease Center(2), it was estimated that 60% of children and 41% of adults who were diagnosed with celiac disease were asymptomatic when they received their diagnosis. Yes, asymptomatic. That means they didn't have any clue that they were negatively, medically, affected by gluten. One can only imagine in highly-maintained, otherwise "fit" populations, such as athletes who are striving for peak health, aimed at peak performance, these sample numbers might be even higher. These numbers seem to imply that it is very likely that athletes who see an increase in athletic performance may, indeed, be suffering from either celiac disease or non-celiac gluten intolerance symptoms…that they didn't even know they had.

However, that being said, it might be next to impossible to render a celiac diagnosis without subjecting the athlete to a rash of testing which will include the request that they, once again, consume gluten. (Try telling an athlete who is performing better than ever to change their ways. It's not likely to happen, especially during peak season.) Adding to the difficulty in diagnosis of gluten sensitivity is the lack of a verified blood or stool marker. The closest factor that can be studied to determine gluten sensitivity is the AGA-IgG antibodies. (Antibodies the body from exposure to "foreign" substances. AGA stands for antigliadin antibodies, which are antibodies produced by the body in response to contact with gliadin, a part of the gluten molecule. IgG stands for immunoglobulin G, which are generalized antibody molecules(3)) While it is true that about 40% of people with proven gluten sensitivity have elevated AGA-IgG, it is also true that about 15-25% of healthy individuals also have elevated AGA-IgG. Therefore, about 60% of gluten sensitive people do not have elevated AGA-IgG (making the test not sensitive enough); and about 20% of "normal", or non-gluten sensitive people have elevated AGA-IgG for no apparent reason (making the test not specific enough(4)).

In either case, many high-level athletes are finding comfort and elevated performance in a gluten-free diet. In The Gluten-Free Edge: A Nutrition and Training Guide for Peak Athletic Performance and an Active Gluten-Free Life (Bronsky, McLean Jory, Yoder Begley, Published by The Experiment, December 2012) there are several real-life gluten-free athletes who are discussed. They also provide insight into the "fuel" these athletes use instead of typical carbohydrates found in wheat-based pastas and products. There are also several websites dedicated to the insights, training methods, and nutrition of athletes that also promote the gluten-free diet to promote enhanced performance, better recovery, and increased stamina as a result of stabilized blood sugars (reducing the hypoglycemic effect of intense exercise) as well as decreased inflammation, and leaner muscle.


  1. National Institutes of Health, Univ. of Chicago Celiac Disease Center, May 7, 2013.
  2. A multi-center study on the sero-prevalence of celiac disease in the United States among both at risk and not at risk groups. Fasano et. al., Archives of Internal Medicine. February 2003.
  3. Celiac Disease Center at Columbia University. February 14, 2011.
  4. Detection of secretory IgA antibodies against gliadin and human tissue transglutaminase in stool to screen for coeliac disease in children: validation study (Published 26 January 2006) BMJ 2006;332:213 welcomes your comments below (registration is NOT required).

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