Bifidogenic

Bifidogenic effect of whole-grain wheat during a 12-week energy-restricted dietary intervention in postmenopausal women

EG Christensen¹, TR Licht¹, M Kristensen² and MI Bahl¹

¹Division of Food Microbiology, National Food Institute, Technical University of Denmark, Søborg, Denmark and ²Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, Copenhagen, Denmark.

Abstract

BACKGROUND/OBJECTIVES: Consumption of whole-grain products is known to have beneficial effects on human health. The effects of whole-grain products on the intestinal microbiota and intestinal integrity have, however, only been studied limitedly. We investigate changes of the human gut microbiota composition after consumption of whole-grain (WW) or refined wheat (RW) and further study effects on gut wall integrity.

SUBJECTS/METHODS: Quantitative PCR was used to determine changes in the gut bacterial composition in postmenopausal women following a 12-week energy-restricted dietary intervention with WW (N¼38) or RW (N¼34). Intestinal integrity was determined by measuring trans-epithelial resistance (TER) across a Caco-2 cell monolayer, following exposure to faecal water.

RESULTS: No significant differences in microbiota composition were observed between the two dietary groups; however, the whole-grain intervention increased the relative abundance of Bifidobacterium compared to baseline, supporting a prebiotic effect of whole-grain wheat. Faecal water increased TER independent of dietary intervention, indicating that commensal bacteria produce metabolites that generally provide a positive effect on intestinal integrity. Combining microbiota composition data from the run-in period with its effect on TER revealed a tendency for a negative correlation between the relative abundance of Bifidobacterium and TER (P¼0.09). This contradicts previous findings but supports observations of increased Salmonella infection in animal models following treatment with bifidogenic prebiotics.

CONCLUSIONS: The present study shows that whole-grain wheat consumption increases the abundance of bifidobacteria compared to baseline and may have indirect effects on the integrity of the intestinal wall.