‘Variable impacts’ on calcium absorption with prebiotic supplement after gastric bypass
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Postmenopausal women who received a daily prebiotic supplement years after gastric bypass saw no change in calcium absorption compared with women who received placebo, though some differential responses were observed in the prebiotic group.
In a small study of women who underwent Roux-en-Y gastric bypass a mean 5 years before the study, researchers noted the wide CIs among women in the prebiotic group suggest a “variable impact” of soluble corn fiber that may be attributed to the degree of gut microbiome alteration and said larger and longer studies are needed.
“Gastric bypass surgery continues to have a significant effect on the intestinal calcium absorption capacity years out from surgery,” Karin Wu, MD, a fellow in the Benioff Center for Microbiome Medicine at the University of California, San Francisco, told Healio. “Daily prebiotic supplementation with soluble corn fiber had variable impacts on intestinal calcium absorption in postmenopausal women who were post-gastric bypass, with those with greater changes in the gut microbiome having the most benefit.”
Wu and colleagues analyzed data from 20 postmenopausal women with a history of Roux-en-Y gastric bypass a mean 5 years before baseline. Researchers randomly assigned women to a 2-month course of 20 g per day soluble corn fiber to augment colonic calcium absorption or maltodextrin placebo orally. Researchers assessed the effects of soluble corn fiber on fractional calcium absorption, biochemical parameters and the fecal microbial composition. The primary outcome of between-group difference in absolute change in fractional calcium absorption was measured with a gold standard dual stable isotope method. Other measures included supplement tolerability, adherence, serum calciotropic hormones and bone turnover markers, and fecal microbial composition via 16S rRNA gene sequencing.
At baseline, mean fractional calcium absorption among study participants was 5.5%.
Compared with maltodextrin placebo, researchers did not observe between-group differences in mean change in fractional calcium absorption, calciotropic hormones or bone turnover markers. Women who received the prebiotic had a wider variation in fractional calcium absorption change vs. women assigned placebo (13.4% vs. 7%). Those with greater change in microbial composition following prebiotic treatment also had a greater increase in fractional calcium absorption (r2 = 0.72; P = .05).
There were no between-group differences in gastrointestinal adverse events.
“The drastic decrease in intestinal calcium absorption to less than 10% after gastric bypass surgery persists years out from surgery, suggesting the importance of continued attention to calcium intake to prevent subsequent metabolic bone disease,” Wu told Healio. “Strategies to augment calcium absorption should be further investigated in this population.”
For more information:
Karin Wu, MD, can be reached at karin.wu@ucsf.edu.
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