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

Abstract

BackgroundMany individuals reduce their bread intake because they believe wheat causes their gastrointestinal (GI) symptoms. Different wheat species and processing methods may affect these responses. ObjectivesWe investigated the effects of 6 different bread types (prepared from 3 wheat species and 2 fermentation conditions) on GI symptoms in individuals with self-reported noncoeliac wheat sensitivity (NCWS). MethodsTwo parallel, randomized, double-blind, crossover, multicenter studies were conducted. NCWS individuals, in whom coeliac disease and wheat allergy were ruled out, received 5 slices of yeast fermented (YF) (study A, n = 20) or sourdough fermented (SF) (study B, n = 20) bread made of bread wheat, spelt, or emmer in a randomized order on 3 separate test days. Each test day was preceded by a run-in period of 3 d of a symptom-free diet and separated by a wash-out period of ≥7 d. GI symptoms were evaluated by change in symptom score (test day minus average of the 3-d run-in period) on a 0–100 mm visual analogue scale (ΔVAS), comparing medians using the Friedman test. Responders were defined as an increase in ΔVAS of ≥15 mm for overall GI symptoms, abdominal discomfort, abdominal pain, bloating, and/or flatulence. ResultsGI symptoms did not differ significantly between breads of different grains [YF bread wheat median ΔVAS 10.4 mm (IQR 0.0–17.8 mm), spelt 4.9 mm (−7.6 to 9.4 mm), emmer 11.0 mm (0.0–21.3 mm), P = 0.267; SF bread wheat 10.5 mm (−3.1 to 31.5 mm), spelt 11.3 mm (0.0–15.3 mm), emmer 4.0 mm (−2.9 to 9.3 mm), 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). ConclusionsThe majority of NCWS individuals experienced some GI symptoms for ≥1 of the breads, but on a group level, no differences were found between different grains for either YF or SF breads. Clinical Trial Registryclinicaltrials.gov, NCT04084470 (https://classic.clinicaltrials.gov/ct2/show/NCT04084470).