Image courtesy Brian Carson, Creative Commons License.
One week ago today, on January 20, the New York Times published an article about recent research regarding the gluten-free diet and athletic performance. Others, including Men’s Fitness and Condé Nast’s Ars Technica, have chimed in as well, with inflammatory headlines such as “athletes shouldn’t stray from gluten” and “gluten-free sports diets do nothing.” As a gluten-free endurance athlete with celiac disease, I read these articles with a mix of interest and disappointment, especially regarding their factual errors and important oversights.
New York Times writer Gretchen Reynolds cites a 2015 Australian study of almost 1,000 athletes, noting that 41 percent reported following a GFD but “only 13 percent had received a formal medical diagnosis of celiac disease.” In fact, the researchers’ study was of non-celiac athletes, so while study participants likely included athletes with undiagnosed celiac disease, the 13 percent Reynolds notes were rather athletes with clinically diagnosed non-celiac gluten sensitivity and other conditions.
However, a 2012 University of Colorado survey of nearly 300 cyclists similarly found 43 percent were following a GFD and, notably, 12 percent of overall respondents had celiac disease. This latter statistic is striking, since it’s 1,100 percent higher than the 1-percent prevalence of celiac disease in the general population. Was there some survey bias that attracted more celiac cyclists to the study? (Possibly.) Are patients with celiac disease somehow much more likely to become athletes than the average person? (Doubtful.) Or perhaps might celiac disease actually be significantly more prevalent among athletes, potentially due in part to the stress of an athlete’s training load that “turns on” the celiac disease genes present (but usually dormant) in one-third of the general population?
This latter possibility is consistent with my anecdotal observations interviewing dozens of elite athletes—many with celiac disease—for my book The Gluten-Free Edge, coauthored with Melissa McLean Jory. In many cases, their celiac disease presented with a large increase in training load, such as the transition from high school to collegiate athletics, or when turning from amateur to pro status. The GFD’s possible protective effect to prevent athletes from developing celiac disease and related conditions in the first place is worthy of further investigation.
Finally, Reynolds emphasizes another Australian study published last month that supposedly disproves the GFD’s positive influence on athletic performance. An alternate title for that study could read, “A very small group of regular athletes try a GFD, eat gluten for just one week, and see what happens.” The laughably small study size included just 13 cyclists, each exposed to a 7-day gluten-containing diet amidst an otherwise GFD regimen. Researchers measured both cycling performance and blood samples from the athletes.
Yet the University of Chicago Celiac Disease Center recommends a gluten challenge lasting 12 weeks to maximize the probability of a proper diagnosis (i.e., minimize false negatives) for patients being blood screened for suspected celiac disease. Did the Australian researchers expect a single week of eating gluten to manifest as measurable differences in both athletic performance and blood markers in “regular” non-celiac athletes?
A GFD and its implications for athletes and their performance is not black and white, all or nothing. Celiac disease, non-celiac gluten sensitivity, wheat allergy, and other medical conditions that demand or positively respond to a GFD introduce many shades of gray. So does the difference between recreational athletes and elite athletes looking to squeeze the last single percentage points of performance out of their bodies, and for whom subtle influences of a GFD could prove meaningful. Not to mention the importance of long-term issues of chronic inflammation, recovery, digestive distress, and other issues that wouldn’t respond to short-term trials like the Australian study.
Reynolds and the Australian researchers acknowledge as much (though the NYT article downplays these important caveats). And when Reynolds writes that “a gluten-free diet is not a panacea,” I wholeheartedly agree. It is no silver bullet, and will not transform overnight the performance of any athlete. Individual biology and other variables heavily influence the impact of a GFD, from profound for an athlete like me with celiac disease to subtle or even nonexistent for other “regular” athletes.
But it remains dangerously dismissive to take an exceptionally small study with obvious limitations and broadcast gross generalized conclusions from it. The GFD and its impact on the performance of many types of athletes is worthy of further study, with more-carefully and better-constructed studies that can truly provide insight into the diet’s potential effects for the health and performance of non-celiac athletes. For some athletes I full expect it will prove an empty promise. For others—as it has been for me—the GFD is the key, not only to superior athletic performance, but to basic health and quality of life. And for many others, the truth will likely be somewhere between the black and the white.