Plain language summary
The gluten-free diet (GFD) has gained increasing popularity among healthy people without coeliac disease or wheat allergy. The main reasons for following a GFD are weight control, the perception that a GFD is healthier, and the presence of symptoms after gluten ingestion. The aim of this study was to address the hypothesis that adding gluten to the diet results in a self-reported worsening of gastrointestinal symptoms (primary outcome) and mental health (key secondary outcomes) in a well-characterised group of adolescents. This study was arranged in two phases; the first phase began with 2 weeks of a GFD, and if the participants responded to the GFD, they proceeded to phase 2. Phase 2 was a double-blinded randomised trial with cross-over and consisted of three periods, each lasting 7 days: (1) a challenge with gluten/placebo, (2) wash-out phase, and (3) the second challenge with placebo/gluten. Results show that it was not possible to detect a difference in symptoms between gluten and placebo at a group level. Furthermore, on an individual level, there was a comparable number of gluten responders and placebo responders, underscoring the insignificant difference between gluten and placebo. Authors conclude that adding gluten to the diet does not induce gastrointestinal symptoms or worsened mental health in adolescents.
Abstract
BACKGROUND The popularity of the gluten-free diet and sales of gluten-free products have increased immensely. AIMS To investigate whether gluten induces gastrointestinal symptoms, measured by self-reported questionnaires, as well as mental health symptoms in adolescents from a population-based cohort. METHODS The eligible participants (n = 273) were recruited from a population-based cohort of 1266 adolescents and had at least four different gastrointestinal symptoms. Phase one (n = 54) was a run-in phase where the participants lived gluten-free for 2 weeks. If they improved they continued to phase 2 (n = 33), a blinded randomised cross-over trial. Participants were blindly randomised either to start with 7 days of gluten, eating two granola bars containing 10 g of gluten or to 7 days on placebo, eating two granola bars without gluten, followed by the reverse and separated by a 7-day washout period. The effects of the intervention on gastrointestinal symptoms and mental health symptoms were assessed. RESULTS In total, 54/273 participants entered the run-in phase and 35 were eligible for randomization. A total of 33 were randomised and 32 completed the trial. The median age was 20.3 (IQR 19.2-20.9) and 32/33 participants were females. Compared with a placebo, gluten did not induce gastrointestinal symptoms. The difference in the average VAS was -0.01 (95% confidence interval -2.07 to 2.05). Nor did we find a difference in the outcomes measuring mental health. CONCLUSION Compared with placebo, adding gluten to the diet did not induce gastrointestinal symptoms or worsened mental health in adolescents recruited from a population-based cohort. The trial registration number is NCT04639921.
Methodological quality
Jadad score
:
5
Allocation concealment
:
Yes
