This study aims to assess the differences in tolerability of differently manufactured wheat breads in a target group of individuals with suspected wheat sensitivity. Additionally, it will be verified, if the absence of a response to oral exposure to defined bread types is associated with an absence of mucosal changes following CLE-assisted mucosal provocation with bread.

Nowadays, more than 20% of people in industrialized countries suffer from a food intolerance or food allergy, with wheat and gluten intolerances on the rise. Besides the well-known conditions celiac disease and wheat allergy, another clinical entity called non-celiac wheat sensitivity (NCWS) was described, which is not yet widely understood. Resulting from inconsistent diagnostic criteria the prevalence of NCWS varies from 0.5% to 13%.

Due to the lack of validated diagnostic criteria and/or appropriate biomarkers for diagnosis of NCWS, it can currently only be suspected by exclusion of other diseases. To verify suspected NCWS, a double-blind placebo-controlled food challenge with wheat is recommended. A confocal laser endomicroscopy (CLE) with endoluminal provocation can also provide meaningful results on the individual intestinal mucosal response to specific allergens.

Furthermore, it is as yet unclear whether NCWS is triggered by gluten, FODMAPs, or other wheat components such as α-amylase trypsin inhibitors. Bread manufacturing processes can influence the composition of bread and the presence of possible triggers of intolerance reactions.

This study aims to investigate the tolerability of differently manufactured wheat breads in individuals with suspected NCWS. Additionally, we expect this approach to improve the currently inadequate diagnosis of NCWS, as well as to provide a better understanding of the underlying mechanisms.

Therefore, individuals with suspected NCWS are included in the trial. Five different types of bread will be tested, including 3 differently manufactured wheat breads, a gluten free bread and a gluten free bread with added wheat flour. Aim of this part is to test a possible psychological factor in NCWS symptoms.

Inclusion Criteria:

• Age ≥18 ≤75 years
• Signed declaration of consent
• Willingness to adhere to the prescribed diet for the duration of the study
• Chronic gastrointestinal symptoms for at least 6 months
• Anamnestic wheat sensitivity
• No acute or chronic gastrointestinal diseases (e.g. celiac disease / wheat allergy)
• No or stable medication for at least 3 months
• No participation in another clinical trial (current or within the past 30 days)

Exclusion Criteria:

• Taking intestinal therapeutics, antibiotics, immunosuppressants, anti-allergic medication or similar
• Pregnancy / lactation
• Occurrence of relevant diseases (possibly individual decision)
• Revocation of consent
• Concurrent participation in another clinical study