An inulin-type fructan enhances calcium absorption primarily via an effect on colonic absorption in humans.
Calcium absorption efficiency and bone mineral mass are increased in adolescents who regularly consume inulin-type fructans (ITF). The mechanism of action in increasing absorption is unknown but may be related to increased colonic calcium absorption. We conducted a study in young adults designed to evaluate these mechanisms with a kinetic technique using (42)Ca orally and (46)Ca dosed i.v. Those who responded to 8 wk of supplementation with 8 g of a mixed short and long degree of polymerization ITF by increasing their calcium absorption had kinetic measurements analyzed to evaluate the time course of absorption. The area under the curve of the oral tracer in the blood during the 26 h after dosing was calculated and the time dependence of increased absorption determined. Eight young adults (of 13 studied), with mean calcium intake approximately 900 mg/d, responded to the ITF with an increased calcium absorption of at least 3%. In responders, absorption increased from 22.7 +/- 11.3% to 31.0 +/- 15.3%. Colonic absorption, defined as absorption that occurred >7 h after oral dosing, represented 69.6 +/- 18.6% of the increase, or 49 +/- 28 mg/d. These findings suggest that, in those who respond to ITF, its effects on calcium absorption occur principally in the colon. This benefit to ITF may be especially important when absorption in the small intestine is impaired for anatomic or physiological reasons.
Abrams
Steven A
SA
Section of Neonatology, Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030, USA. sabrams@bcm.edu
Hawthorne
Keli M
KM
Aliu
Oluseyi
O
Hicks
Penni D
PD
Chen
Zhensheng
Z
Griffin
Ian J
IJ
D000328:Adult; D019540:Area Under Curve; D002118:Calcium / Q000008:administration & dosage / Q000378:metabolism / Q000493:pharmacokinetics*; D003106:Colon / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D005260:Female; D005630:Fructans / Q000737:chemistry* / Q000494:pharmacology*; D006801:Humans; D007408:Intestinal Absorption / Q000187:drug effects*; D007444:Inulin; D008297:Male; D013997:Time Factors
D005630:Fructans; D007444:Inulin; D002118:Calcium