Soluble corn fiber modulates calcium absorption by altering colonic microbiota

Abstract

Soluble corn fiber (SCF) has been shown to increase calcium (Ca) absorption. Animal models suggest colonic bacteria can influence Ca absorption; the mechanism is not understood in humans. This study assessed the effect of SCF on fecal microbiota in relation to Ca absorption in a racially diverse group of teens. Twenty‐four boys and girls (12–15 y; 45.8% Asian, 25% Hispanic, 29.2% Multiracial) participated in two 3‐week metabolic Ca balance studies testing 0 and 12 g/d SCF on a low Ca diet (600 mg/d), characteristic of usual intakes. Microbial community composition, evaluated in fecal samples collected during each treatment, was assessed with 454 pyrosequencing of PCR amplified 16S rRNA genes. Ca absorption increased by 12% with SCF consumption compared to no SCF. This increase correlated with a decrease in other Erysipelotrichaceae (P<0.04) and increases in Bacteroides (P<0.03), Alistipes (P<0.05), Butyricicoccus (P<0.04), Oscillibacter (P<0.008) and Dialister (P<0.003) but not changes in Lactobacillus (P=0.07) and Parabacteroides (P=0.07). These bacterial genera have been identified as short chain fatty acid producers while Bacteroides is capable of fermenting fibers like SCF. The bacterial changes suggest SCF may increase Ca absorption through fermentation. This is the first study to show that increases in specific bacteria were significantly correlated with the observed increase in calcium absorption.Grant Funding Source: Tate & Lyle Health & Nutrition Sciences