No effects of gluten in patients with self-reported non-celiac gluten sensitivity after dietary reduction of fermentable, poorly absorbed, short-chain carbohydrates.
Level 2 - randomized trial
Double-blind randomized crossover challenge trial
PubMed 23648697 · doi:10.1053/j.gastro.2013.04.051
What was done
Researchers conducted a double-blind crossover trial in 37 adults (aged 24 to 61 years, 6 men) with self-reported non-celiac gluten sensitivity and irritable bowel syndrome, ruling out celiac disease. Participants followed a 2-week low-FODMAP run-in diet and were then randomly assigned to 1-week challenge periods with high-gluten (16 g/day), low-gluten (2 g/day plus 14 g/day whey protein), or control (16 g/day whey protein) separated by at least 2-week washout periods. Visual analogue scales were used to track gastrointestinal symptoms and fatigue, and serum and fecal markers of inflammation, intestinal injury, and immune activation were measured. A subset of 22 participants subsequently completed a 3-day rechallenge crossover comparing gluten (16 g/day), whey (16 g/day), and a protein-free control.
What was found
Gastrointestinal symptoms improved significantly across all participants during the baseline low-FODMAP diet. During the 1-week challenges, symptoms worsened to a similar degree on both gluten and whey diets, with gluten-specific symptom worsening observed in only 8% of participants. No diet-specific changes occurred in any inflammatory or immune biomarkers. In the secondary 3-day rechallenge, symptoms rose to similar levels across gluten, whey, and protein-free control groups, showing no reproducible gluten-specific effect and demonstrating an order effect.
Why it matters
This study indicates that symptom relief attributed to a gluten-free diet in non-celiac individuals may largely stem from reduced intake of poorly absorbed short-chain carbohydrates (FODMAPs) or expectation effects rather than a specific sensitivity to gluten protein.
Limits
The sample size was small with 37 participants overall and 22 in the second rechallenge phase. The cohort was heavily female-skewed (31 of 37 participants), challenge durations were relatively short (1 week and 3 days), and all participants had concurrent irritable bowel syndrome, which may not represent all individuals who report sensitivity to wheat products.
Cited by
- supports A clinical study demonstrated that individuals self-identifying as gluten sensitive experienced severe abdominal bloating and symptoms when fed gluten-free bread they believed contained gluten (a nocebo effect).