Abstract

CONTEXT: The adverse skeletal effects of Roux-en-Y gastric bypass (RYGB) are partly caused by intestinal calcium absorption decline. Prebiotics, such as soluble corn fiber (SCF), augment colonic calcium absorption in healthy individuals.OBJECTIVE: We tested the effects of SCF on fractional calcium absorption (FCA), biochemical parameters, and the fecal microbiome in a post-RYGB population. Design, Setting, Participants : Randomized, double-blind, placebo-controlled trial of 20 postmenopausal women with history of RYGB mean 5 years prior.INTERVENTION: 2-month course of 20g/day SCF or maltodextrin placebo orally.MAIN OUTCOMES: Between-group difference in absolute change in FCA (primary outcome) was measured with a gold-standard dual stable isotope method. Other measures included tolerability, adherence, serum calciotropic hormones and bone turnover markers, and fecal microbial composition via 16S rRNA gene sequencing.RESULTS: Mean FCA ±SD at baseline was low at 5.5±5.1%. Comparing SCF to placebo, there was no between-group difference in mean (95% CI) change in FCA (+3.4 [-6.7,+13.6]%), nor in calciotropic hormones or bone turnover markers. The SCF group had a wider variation in FCA change than placebo (SD 13.4% vs. 7.0%). Those with greater change in microbial composition following SCF treatment had greater increase in FCA (r 2=0.72,p=0.05). SCF adherence was high, and GI symptoms similar between groups.CONCLUSIONS: No between-group differences were observed in changes in FCA or calciotropic hormones, but wide confidence intervals suggest a variable impact of SCF that may be due to the degree of gut microbiome alteration. Daily SCF consumption was well-tolerated. Larger and longer-term studies are warranted.

View details for DOI 10.1210/clinem/dgab883

View details for PubMedID 34888663