Patients with diarrhea-predominant irritable bowel syndrome could benefit from a gluten-free diet.
Dr Michael Camilleri and colleagues from Minnesota, USA performed a randomized controlled 4-week trial of a gluten-containing diet or gluten-free diet in 45 patients with IBS-D.
Genotype analysis was performed for HLA-DQ2 and HLA-DQ8.
The research team placed 22 patients on the gluten-containing diet, and 23 patients were placed on the gluten-free diet.
The research team measured bowel function daily, small-bowel and colonic transit, mucosal permeability, and cytokine production by peripheral blood mononuclear cells after exposure to gluten and rice.
The team collected rectosigmoid biopsy specimens from 28 patients, analyzed levels of messenger RNAs encoding tight junction proteins, and performed H&E staining and immunohistochemical analyzes.
Analysis of covariance models was used to compare data from the gluten-containing diet and gluten-free diet groups.
|Gluten-containing diet was associated with higher small bowel permeability|
Subjects on the gluten-containing diet had more bowel movements per day.
The research team found that gluten-containing diet had a greater effect on bowel movements per day of HLA-DQ2/8–positive than HLA-DQ2/8–negative patients.
The gluten-containing diet was associated with higher small bowel permeability.
The team observed that SB permeability was greater in HLA-DQ2/8–positive than HLA-DQ2/8–negative patients.
No significant differences in colonic permeability were observed.
Patients on the gluten-containing diet had a small decrease in expression of zonula occludens 1 in small bowel mucosa and significant decreases in expression of zonula occludens 1, claudin-1, and occludin in rectosigmoid mucosa.
The effects of the gluten-containing diet on expression were significantly greater in HLA-DQ2/8–positive patients.
The team noted that gluten-containing diet vs the gluten-free diet had no significant effects on transit or histology.
Peripheral blood mononuclear cells produced higher levels of interleukin-10, granulocyte colony-stimulating factor, and transforming growth factor-α in response to gluten than rice.
Dr Camilleri's team concludes, "Gluten alters bowel barrier functions in patients with IBS-D, particularly in HLA-DQ2/8–positive patients."
"These findings reveal a reversible mechanism for the disorder."