Celiac disease in athletes: How to adapt your fueling strategy

Ask any athlete who has been diagnosed with celiac disease to describe the months before their diagnosis, and you'll often hear a version of the same story: "something just didn't feel right". The symptoms are notoriously varied and easy to miss.

Researchers have described celiac as a "clinical chameleon" — for one athlete it can present as a series of bone stress injuries, for another it looks like persistent anemia and fatigue, whilst others might experience gastrointestinal symptoms, and 21% of adults have no symptoms at all at the time of diagnosis.

The wide range of presentations explains why celiac disease is severely underdiagnosed — studies suggest that 70% of people with the disease aren't diagnosed, and the average time from symptom onset to diagnosis is typically 11 years.

What is celiac disease?

Celiac disease is an autoimmune condition in which the body identifies gluten (a protein found in wheat, barley, and rye) as a foreign invader. The body mounts an attack on gluten and destroys the lining of the small intestine in the process. This lawnmower effect on the intestinal villi hinders nutrient absorption and impacts a wide range of systems. You must have at least one permissive gene to develop celiac disease, though not all genetically predisposed individuals will. Celiac runs in families, and people can test negative on biopsy and still develop the disease later in life, which is what happened to me. 

Lifelong adherence to a strict gluten-free diet is the only treatment. Athletes must avoid gluten-containing foods and also cross-contaminants — just 1/350th of a piece of bread can trigger an autoimmune reaction. For athletes, this can complicate fueling, team meals, race travel, and sports nutrition choices.

It's also worth distinguishing celiac from non-celiac gluten sensitivity (NCGS). Gluten sensitivity involves an innate immune response and causes real symptoms, but does not produce the same intestinal damage. People with NCGS generally have less need to worry about cross-contaminants and do not require the same ultra-strict protocols. For confirmed celiac athletes, that strictness is non-negotiable.

How celiac disease affects performance

Performance declines are inevitable without proper nutrient absorption. Two hallmark symptoms of celiac disease are chronic fatigue and iron deficiency anemia, which are present in 32% of adults at diagnosis and often the sole finding pre-diagnosis. Other common deficiencies include calcium, vitamin D, folic acid, vitamin B12, magnesium, and copper — with inadequate levels undermining energy, recovery, and training adaptations.

Primarily due to malabsorption of calcium and vitamin D, athletes with undiagnosed celiac are at elevated risk for low bone mineral density and bone stress injuries. Upon diagnosis, a DEXA scan and full micronutrient panel are essential first steps. IRONMAN 70.3® World Champion Lucy Charles-Barclay has been open about her celiac diagnosis, which contributed to multiple bone stress injuries, chronic joint pain, and performance declines. She described her diagnosis as a "lightbulb moment" and has credited a gluten-free diet with dramatically improving her energy and eliminating joint pain.

Other symptoms of celiac include GI distress (bloating, diarrhea, abdominal pain), skin rashes, neurological symptoms, headaches, and mental health challenges — all of which can masquerade as overtraining, Relative Energy Deficiency in Sport (REDs), or general burnout in athletes.

How to adapt to a strict gluten-free diet

A celiac diagnosis requires overhauling how you eat, shop, cook, travel, and socialise around food. And, luckily, athletes already have the skill set to develop systems that keep them healthy: discipline, protocol adherence, and the ability to adapt to unforeseen challenges. 

Sports nutrition products are a critical starting point. Cross-contamination during manufacturing is a real risk and often undisclosed. The safest products carry a certified gluten-free label (GFCO, GFFP, Beyond Celiac and NSF). If a product is labeled gluten-free in the US, it must be contain less than 20ppm gluten (considered safe for those with celiac). If the product does not say gluten-free on the label, it is best to inquire about manufacturing processes and cross-contamination. Precision Fuel & Hydration's products are safe for celiac athletes, with the sole exception of the PF 30 Chews which are manufactured in a facility that handles gluten (but with a very low risk of cross-contamination). Always vet other brands individually before using them and check back to make sure manufacturing processes haven’t changed.

At home, dedicate separate cutting boards, toasters, colanders, sponges and wooden utensils for gluten-free use only. Assign gluten-free preparation and storage areas, and sanitise those surfaces before food prep. Because 'double dipping' can cause an auto-immune reaction, use squeeze bottles for condiments or sharpies to label items like peanut butter. You can also choose single use packets of nut butters, etc. Store gluten-free products above gluten-containing foods to prevent crumb contamination, and educate housemates on the stakes.

Travelling to races means losing control of your food environment at the worst possible time. Research restaurants in advance using the Find Me Gluten Free app, book accommodation with a kitchenette when possible and pack safe staples — microwavable rice, nut butter packets, certified bars, and Precision Hydration electrolytes. I typically pack a travel toaster and my preferred gluten free bagel so race morning breakfast tastes better.

At restaurants, call ahead, speak directly with the manager or chef, and frame your needs as a medical condition — not a preference. With coaches and teammates, be direct and unapologetic. Brief your support staff early so team meals can be planned accordingly. The athletes who navigate celiac most successfully are the ones who normalise talking about it.

Coping with a celiac diagnosis

A celiac diagnosis can be disorienting — there may be grief for the food culture you're leaving behind, and frustration at the planning, label reading and system creation that inevitably lies ahead. But for many athletes, it is ultimately clarifying. It is an answer, a path forward.

The intestinal damage caused by celiac is reversible with strict dietary adherence, and downstream effects — deficiencies, fatigue, bone loss — can be addressed with targeted nutrition support. Athletes who thrive post-diagnosis have the right team: a gastroenterologist, a sports dietitian with celiac expertise, a GI psychologist (when needed) and a support system that understands the demands of the condition.

If any of this resonates, push for testing — including genetic testing. And if you've just been diagnosed, here's what I want you to know: this is not the end of your athletic story. Lucy Charles-Barclay, Emma Janell Bates, and many athletes — myself included — are living proof that the other side of a celiac diagnosis can mean better energy, fewer injuries, and performance you didn't think was possible.

Further reading

• How strong electrolyte drinks can help POTS sufferers
• Cystic Fibrosis and 'Salty Sweaters'