A gluten metabolism study in healthy individuals shows the presence of faecal glutenasic activity.

PURPOSE: To study the gluten metabolism in healthy individuals and its effect over the intestinal microbial activity. METHODS: The faeces of eleven healthy subjects were analysed under 4 diet regimens: their normal gluten diet, a strict gluten-free diet (GFD), a GFD with a supplemental intake of 9 g gluten/day and a GFD with a supplemental intake of 30 g gluten/day. Gluten content, faecal tryptic activity (FTA), short-chain fatty acids (SCFAs) and faecal glutenasic activity (FGA) were analysed in faecal samples. RESULTS: Faecal gluten contents, FTA, SCFAs and FGA varied significantly with different levels of gluten intake in the diet. When high gluten doses (30 g/day) were administered in the diet, SCFA concentrations (70.5 mmoles/kg faeces) were significantly different from those from the GFD period (33.8 mmoles/kg faeces) of the experiment. However, the FTA showed significant differences between the GFD (34 units) and the normal gluten-containing diet (60 units) and also between the GFD and the GFD + 30 g of gluten/day (67 units). When gluten was present in the diet, gluten was detected in the faeces, showing that at least a portion of the gluten ingested is eliminated in the large intestine, providing a substrate for intestinal microbial proteases. We have also shown the presence of faecal glutenasic activity that increased proportionally with the gluten intake in the diet, showing an enzymatic activity of 993 units in DSG, 2,063 units in DSG + 9 g and 6,090 units in DSG + 30 g. CONCLUSIONS: The activity of the intestinal microbiota is modified by gluten intake in the diet. The incorporation of gluten in the diet increases the activity of a gluten proteolytic activity in the faeces.

Differences of small intestinal bacteria populations in adults and children with/without celiac disease: effect of age, gluten diet, and disease.

BACKGROUND: Scientific evidence has revealed microecological changes in the intestinal tract of celiac infants. The objective of this work is the study of bacterial differences in the upper small intestine in both adults (healthy, untreated celiac disease [CD], and CD treated with a gluten-free diet) and children (healthy and untreated CD). METHODS: Intestinal bacterial communities were identified by 16S rRNA gene sequencing of DNA extracted from duodenal biopsies. RESULTS: Analysis of the sequences from adults and children showed that this niche was colonized by bacteria affiliated mainly with three phyla: Firmicutes, Proteobacteria, and Bacteroidetes. In total, 89 different genera were identified in adults and 46 in children. Bacterial richness was significantly lower in the children than in the adults. A global principal component analysis of the bacterial communities of both healthy and untreated CD patient groups (including both children and adults) revealed a strong effect of age in principal component 1--clustering all adults and children separately--and a possible effect of the disease in adults with untreated patients clustering separately. CONCLUSIONS: There are bacterial differences in the upper small intestine between untreated children CD patients and untreated CD adults due to age. There are bacterial differences in the upper small bacteria microbiota between treated and untreated CD adults due to treatment with a gluten-free diet.