No Effects of a Short-Term Gluten-free Diet on Performance in Nonceliac Athletes (nor would one be expected)

Med Sci Sports Exerc. 2015 May 12. [Epub ahead of print]

No Effects of a Short-Term Gluten-free Diet on Performance in Nonceliac Athletes.

Lis D1, Stellingwerff T, Kitic CM, Ahuja KD, Fell J.

Author information

• 11 Sport Performance Optimization Research Team, School of Health Sciences, University of Tasmania, Launceston, Tasmania, Australia 2 Canadian Sports Institute - Pacific, Victoria, British Columbia, Canada.

Abstract

PURPOSE:

Implementation of gluten-free diets amongst non-celiac athletes has rapidly increased in recent years due to perceived ergogenic and health benefits. The aim of this study was to investigate the effects of a gluten-free diet (GFD) on exercise performance, gastrointestinal (GI) symptoms, perceived well-being, intestinal injury, and inflammatory responses in non-celiac athletes.

METHODS:

Thirteen competitive endurance cyclists (8 males, 5 females) with no positive clinical screening for celiac disease or history of irritable bowel syndrome (mean±SD; age: 32±7 years; weight: 71.1±13.4kg; height 177.0±11.8cm, VO2max 59.1±8.0ml.kgmin) were allocated to a seven daygluten-containing diet (GCD) or GFD separated by a 10-day washout in a controlled randomized double-blind, cross-over study. Cyclists ate a GFD alongside either gluten-containing or gluten-free food bars (16g wheat gluten per day) while habitual training and nutrition behaviors were controlled. During each diet, cyclists completed the Daily Analysis of Life Demand for Athletes (DALDA) and GI questionnaires (post-exercise and daily). Onday seven cyclists completed a submaximal steady-state (SS) 45 minute ride at 70% peak power followed by a 15 minute time-trial (TT). Blood samples were taken pre-exercise, post SS and post TT to determine intestinal fatty acid binding protein (IFABP) and inflammatory markers (cytokine responses: IL-1β, IL-6, IL-8, IL-10, IL-15, TNF-α). Mixed effect logistic regression was used to analyze data.

RESULTS:

TT performance was not significantly different (p=0.37) between the GCD (245.4±53.4kJ) and GFD (245.0±54.6kJ). GI symptoms during exercise, daily, and DALDA responses were similar for each diet (p>0.11). There were no significant differences in IFABP (p=0.69) or cytokine (P>0.13) responses.

CONCLUSIONS:

A short-term GFD 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.