Data published in the American Journal of Clinical Nutrition also indicated that the intervention was associated with significant increases in a marker of bone-formation of 8%.
“[C]hronic doses of 10 and 20 g fiber from SCF/d were well tolerated by participants and increased bone-calcium retention in free-living postmenopausal women dose dependently. More research is necessary to determine the mechanism that drives the retention, but it likely involves shifts in fiber-fermenting intestinal bacteria or their metabolites as shown in adolescents,” wrote the researchers.
The study was sponsored by Tate & Lyle Ingredients Americas LLC.
Fibers and bones
The study adds to an every growing body of science supporting the potential bone health benefits of prebiotic fiber intake. The fibers are reported to help bone strength by changing the flora in the colon.
The fiber selectively promotes the growth of beneficial bacteria in the gut, which in turn produce short chain fatty acids. These fatty acids decrease the pH within the intestine, and improve the solubility of the minerals present. Calcium is then better absorbed into the body.
The Indiana-based researchers recruited 14 healthy postmenopausal women to participate in their randomized-order, crossover, double-blinded trial. The women were randomly assigned to receive either 0, 10, or 20 grams per day of the corn fiber (Promitor Soluble Corn Fiber 85) for 50 days. This was followed by a washout period before crossing over to one other doses.
Bone calcium retention was measured using urinary levels of the rare radioisotope 41Ca. “41Ca is a virtually stable, long-lived radioisotope ([half life]= 105 y) that can be measured with great sensitivity via accelerator mass spectrometry,” explained the researchers.
Results showed that the 10 and 20 gram per day doses of the soluble corn fiber increased bon calcium retention by 4.8% and 7%, repectively.
While bone turnover biomarkers did not change for any of the interventions, significant increases of the bone formation marker, bone-specific alkaline phosphatase, were reported.
“[A] 7% decrease in the urinary 41Ca:Ca ratio, as was observed in the current study, would result in a positive bone balance of approximately 50 mg Ca/d,” wrote the researchers. “If the entire effect of SCF is realized within 50 d (i.e., the duration of interventions in the current study), a total of 2.5 g bone calcium or 0.3% of [total-body bone mineral content (TBBMC)] would be retained. However, if the effect persists with continued SCF consumption, it would result in an increased balance of 18.25 g bone calcium/y or 2.5% of TBBMC/y. In comparison, 500 mg Ca supplementation/d reduced bone loss by 5.5% of TBBMC.”
Source: American Journal of Clinical Nutrition
Published online ahead of print, doi:10.3945/ajcn.116.132761
“Soluble corn fiber increases bone calcium retention in postmenopausal women in a dose-dependent manner: a randomized crossover trial”
Authors: S.A. Jakeman, et al.