Can the Gluten-Free Diet Help Your Athletic Performance?

Short-Term Study Says No, But More Research Needed

Can the gluten-free diet help athletic performance?. Clive Brunskill/Getty Images

Can the gluten-free diet improve your athletic performance?

If you ask tennis star Novak Djokovic, the answer is "yes, absolutely": Djokovic famously credits his stellar performance to going gluten-free following a diagnosis of non-celiac gluten sensitivity in 2010. 

Djokovic's symptoms included asthma and stomach spasms, along with fatigue that sometimes left him unable to finish tennis matches. Meanwhile, his go-to foods at that time included gluten-filled pizza, pasta and bread.

 He went gluten-free after a physician watching one of his matches (one where he suffered greatly from asthmatic symptoms) contacted him and suggested dietary changes. 

His conversion to a gluten-free lifestyle has led numerous other athletes to try the gluten-free diet, some full-time and others sporadically for a week or two prior to major matches and competitions.

But Can It Bump Up Your Performance?

Despite Djokovic's anecdotal experience, there's zero research showing whether going gluten-free long-term can help athletic performance, and some clinicians speculate that the diet wouldn't provide any boost unless the athlete in question actually suffers from celiac disease or gluten sensitivity. We also have no idea how many tennis players tried the gluten-free diet and didn't become superstars.

One study published in 2013 found that the gluten-free diet reduced body fat, weight and insulin resistance in rats (read here why insulin resistance and metabolic syndrome are something you need to watch out for).

But it's far from clear whether those benefits in rodents would translate to humans (in many cases, subsequent research shows that effects shown in animals don't translate to humans).

Nonetheless, the lack of research hasn't stopped athletes from going gluten-free in search of a performance edge. "Leading up to the London 2012 Olympic Games I was working in Olympic sport in Canada and we practitioners had high numbers of athletes deciding to go gluten-free and reporting it made them feel better and reduced gastrointestinal issues," says Dana Lis, a postgraduate researcher at the University of Tasmania in Australia.

"We had no evidence-based with which to advise a gluten-free diet for non-celiac athletes," Lis says. "An athlete's gut does undergo repeated injury due to reduced blood flow during endurance/strenuous exercise, so maybe there is a reason? We didn't know, so we decided to investigate the issue."

Sole Study Not Promising

In the only study to date covering effects of the gluten-free diet in athletes, Lis and her colleagues considered whether a week-long gluten-free diet could help athletic performance in a small group of competitive endurance cyclists who didn't have celiac disease or a prior diagnosis of irritable bowel syndrome (IBS symptoms can be caused by gluten).

In this study, published in May 2015, eight men and five women followed a gluten-free diet for seven days, then ate their regular diets for 10 days, and then ate gluten-free again for another seven days. For the first seven days, some of the participants also ate a food bar that contained 16 grams of wheat gluten, while the others ate a similar bar with no gluten ingredients.

The groups switched following a 10-day "washout" period when everyone resumed eating their regular diets (and no food bars), with the first group receiving the gluten-free food bar and the second group receiving the gluten-containing bar. The study was blinded, which means none of the participants knew when they were eating gluten.

On the last day of each test period, the cyclists completed a rigorous endurance test to look for differences between gluten-free and gluten-filled diet performance. They also provided blood samples so the researchers could test for inflammatory markers and indicators of injury to the digestive tract.

The results were uninspiring for those who believe the gluten-free diet can help athletic performance: "A short-term gluten-free diet had no overall effect on performance, GI symptoms, well-being, and a select indicator of intestinal injury or inflammatory markers in non-celiac endurance athletes," the researchers concluded.

So What Does This Mean for Gluten-Free Athletes?

The trial only lasted for one week, so it may not represent a fair long-term test of the gluten-free diet in athletes. Nonetheless, Lis notes that symptoms of non-celiac gluten sensitivity generally surface a few hours to a few days following gluten ingestion, so "I am confident this is long enough."

Also, the one-week duration of the trial more accurately reflects the intermittent way in which many athletes eat gluten-free — just for a week or two before an event or a meet, she says. In any event, it would have been difficult to keep the athletes on board for a longer trial, even though that would have been preferable, she adds. The research team now is starting to look at other dietary components, such as those found in the low-FODMAP diet, to see if that might have some effect on gastrointestinal well-being during exercise, she says.

So the bottom line is: a short-term switch to the gluten-free diet doesn't appear, based on this one study, to have much effect on athletic performance. But more research is needed to see if long-term adherence to the diet improves performance in some athletes, as it seems to have done for Novak Djokovic.

Sources:

Lis D et al. No Effects of a Short-Term Gluten-free Diet on Performance in Nonceliac Athletes. Medicine & Science in Sports & Exercise. May 12, 2015. (Author's note: This study was a collaboration between the University of Tasmania and Dr. Trent Stewllingwerff from the Canadian Sport institute Pacific.)

Soares FL et al. Gluten-free diet reduces adiposity, inflammation and insulin resistance associated with the induction of PPAR-alpha and PPAR-gamma expressionThe Journal of Nutritional Biochemistry. 2013 Jun;24(6):1105-11.

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