“Gluten-free” is one of the trendiest terms in nutrition right now. For my last Masters project, I was tasked with choosing a popular diet book and determining if the diet claim was warranted with scientific evidence. I feel like I hear or read the term “gluten-free” on a daily basis, so I chose a book called The Gluten-Free Edge. This book, by Peter Bronski and Melissa McLean Jory, promises that a gluten-free diet will enhance athletic performance in any individual, no matter their skill level or whether they have a gluten intolerance or not. The authors claim that gluten causes a variety of health complications in ALL people, such as “impaired digestion, leaky gut, cell toxicity, gastrointestinal problems, inflammation, [and] neurological effects”(Bronski and McClean Jory, p. 68). They also make the large declaration that omitting gluten from the diet will reduce inflammation, improve digestion, and lead to faster recovery after workouts. The writing is very persuasive, and while reading the book I began to wonder if there was something to all this gluten-free hype. Will jumping on the gluten-free bandwagon make me able to run faster, longer, and harder? In a world that loves nutrition quick fixes, can something as simple as removing gluten from the diet enhance athletic performance? I made it my mission to determine if this claim could be true.
First, let’s start with a quick explanation of gluten and gluten intolerances. Gluten is the main storage protein found in wheat, rye, and barley. Gluten holds baked goods together by giving them structure and sponginess. The most serious sensitivity to gluten is called Celiac Disease, which is an autoimmune disease where a person’s small intestines cannot process gluten. Instead, the gluten is toxic and creates a significant amount of damage to the small intestines. If a person with Celiac Disease goes undiagnosed and continues to eat gluten, they will experience severe symptoms like nausea, diarrhea, vomiting, tiredness, stomach pain, weight loss, and nutrient deficiencies. Only 2-3% of people in the US have Celiac Disease. Other people may experience milder symptoms indicative of a gluten intolerance. In such people, the body acts to repel gluten but it does not attack the small intestines. Diagnosing a gluten intolerance is extremely difficult, and many people will assume that they have a gluten intolerance when that is not the case.
Now back to our main question: Can a gluten-free diet enhance athletic performance? For a dietary claim to be valid, it must be supported with a multitude of scientific research. Studies must be conducted to test a hypothesis, and then the studies should be repeated several times to prove that the findings were not just a fluke. As a Graduate student, I am used to sorting through research to substantiate a claim. So, I began searching for research on a gluten-free diet and how it may affect athletic performance. I came up with zero results. There have been no studies done on this topic, which means that the claim for this book has been based on other research that is not directly related to the main thesis. I decided to see if ANY of the claims in the book were justified, so I changed my search terms. The authors say that athletic performance will be maximized because gluten causes gastrointestinal distress in all individuals and cutting out gluten will extinguish this distress. Therefore, I continued my search for research on gluten and gastrointestinal distress. I found 4 clinical trials that were remotely close to this topic, but the problem was that 3 out of 4 of these trials used subjects with irritable bowel syndrome (IBS). The researchers were trying to see if removing gluten from the diet would ease the IBS. The studies did show that gluten lead to stomach issues in the patients with IBS. Aha! This is where the authors of The Gluten-free Edge got their claim that removal of gluten will ease stomach distress. Further inspection of the book’s references showed 3 out of 4 of these studies listed as sources. Only the 4th study used healthy controls, and this study looked at markers of inflammation in the intestines when eating gliadin (a protein found in gluten). The healthy controls did NOT experience inflammation of the intestines from gliadin. Basically, the main takeaway is that the claim that gluten causes gastrointestinal distress in healthy individuals in not founded in research. It has been extrapolated from research on individuals with IBS, which is very different than doing research on healthy individuals.
So, should you eat a gluten-free bagel before your next race if you are hoping for a PR (personal record)? Simply, the answer is NO. Sadly, nothing will make you a better athlete except training harder and following a proper sports nutrition diet. Quick fixes don’t work for weight loss, and they certainly don’t work for improved athletic performance.
Bronski, R., McLean Jory, M. The Gluten-Free Edge. Emmaus, PA: Rodale; 2013.