Prebiotics may improve calcium absorption in postmenopausal women after gastric bypass

Changes in fractional calcium absorption (FCA) or calciotropic hormones are not significantly different between postmenopausal women with history of Roux-en-Y gastric bypass (RYGB) taking soluble corn fibre (SCF) and those receiving maltodextrin placebo, but the wide confidence intervals (CIs) suggest a variable influence of SCF potentially driven by the degree of gut microbiome alteration, reports a study.

“Prebiotics, such as SCF, augment colonic calcium absorption in healthy individuals,” the researchers said.

A randomized, double-blind placebo-controlled trial was carried out on 20 postmenopausal women who previously underwent RYGB for a mean of 5 years. Participants were randomly assigned to receive a 2-month course of either 20-g/day SCF or maltodextrin placebo taken orally.

The primary outcome was between-group difference in absolute change in FCA, measured with a gold standard dual stable isotope method. Other outcomes measured were tolerability, adherence, serum calciotropic hormones and bone turnover markers, and faecal microbial composition via 16S rRNA gene sequencing.

At baseline, mean FCA among participants was low at 5.5 percent. No between-group difference was seen in mean change in FCA (3.4 percent, 95 percent CI, ‒6.7 to 13.6) and in calciotropic hormones or bone turnover markers.

Interestingly, the SCF group had a wider variation in FCA change than the placebo group (13.4 percent vs 7.0 percent). Women with greater change in microbial composition following SCF treatment had a higher increase in FCA (r², 0.72; p=0.05).

Adherence to SCF was high. In addition, gastrointestinal symptoms were comparable between groups.

“Daily SCF consumption was well tolerated,” the researchers said. “Larger and longer-term studies are warranted.”