Two randomized crossover multicenter studies investigating gastrointestinal symptoms after bread consumption in individuals with noncoeliac wheat sensitivity: do wheat species and fermentation type matter?

Background: Many individuals reduce their bread intake due to the belief that wheat is the cause of their gastrointestinal (GI) symptoms. Different grains and processing methods may impact tolerability.

Objective: We investigated the effects of six different types of bread on GI symptoms in individuals with self-reported non-coeliac wheat sensitivity (NCWS).

Methods: Two parallel randomised double-blind crossover multicentre studies were conducted. NCWS individuals, in whom coeliac disease and wheat allergy were ruled out, received five slices of (study A, n=20) yeast fermented (YF) or (study B, n=20) sourdough fermented (SF) bread made of bread wheat, spelt or emmer on three separate intervention days. Each test day was preceded by a run-in period of 3 days and separated by a wash-out period of at least 7 days. GI symptoms were evaluated by change in symptom score (test day minus average of the 3-day run-in period) on a 0-100mm visual analogue scale (delta VAS). Responders were defined as an increase in delta VAS of at least 15mm for overall GI symptoms, abdominal discomfort, abdominal pain, bloating and/or flatulence.
Results: The overall change in GI symptoms did not differ between breads of different grains (YF p=0.267; SF p=0.144). The number of responders was also comparable for both YF (6 to wheat, 5 to spelt, and 7 to emmer, p=0.761) and SF breads (9 to wheat, 7 to spelt, and 8 to emmer, p=0.761).

Conclusion: The majority of NCWS individuals experienced GI symptoms for at least one of the breads, but on a group level, no differences were found between different grain types for either YF or SF breads.

Clinical Trial Registry: ClinicalTrials.gov, NCT04084470