title: Inulin modifies the bifidobacteria population, fecal lactate concentration, and fecal pH but does not influence iron absorption in women with low iron status.
abstract: BACKGROUND
  Bioavailability of nonheme iron is influenced by the concentration of inhibitors and enhancers in the diet. The fructans inulin and oligofructose have been shown to improve iron absorption in animals through colonic uptake, but this has not been confirmed in humans.
  
  
  OBJECTIVE
  The aim of the intervention study was to evaluate the influence of inulin on iron absorption, bifidobacteria, total bacteria, short-chain fatty acids (SCFAs), and fecal pH in women with low iron status (plasma ferritin <25 μg/L).
  
  
  METHODS
  The subjects (n = 32) consumed inulin or placebo 3 times/d (∼20 g/d) for 4 wk, separated by a 2-wk washout period. Iron absorption was measured after 3 wk of inulin and placebo consumption from a standard test meal by using stable-iron-isotope techniques. Fecal bacteria were measured by quantitative polymerase chain reaction, and fecal acids by HPLC.
  
  
  RESULTS
  Mean fractional iron absorption in the inulin (15.2%; 95% CI: 8.0%, 28.9%) and placebo (13.3%; 95% CI: 8.1%, 24.3%) periods did not differ significantly (P = 0.10). Inulin decreased fecal pH (P < 0.001) and increased fecal bifidobacteria (P < 0.001) and fecal lactate (P < 0.001) but had no effect on fecal SCFAs and total bacteria. Changes in lactate and acetate concentrations were positively correlated with changes in propionate (P < 0.001) and butyrate (P < 0.02) concentrations, respectively. Iron absorption correlated with fecal pH in the placebo period (P < 0.01) but not in the inulin period (P = 0.37).
  
  
  CONCLUSIONS
  Although inulin showed prebiotic activity, we were unable to show an increase in iron absorption in women with low iron status. This trial was registered at clinicaltrials.gov as NCT0148309.
authors: Laboratory of Human Nutrition, Institute of Food, Nutrition and Health, ETH Zurich, Switzerland.
authors: Nicolai
authors: N
authors: Petry
authors: Ines
authors: I
authors: Egli
authors: Christophe
authors: C
authors: Chassard
authors: Christophe
authors: C
authors: Lacroix
authors: Richard
authors: R
authors: Hurrell
mesh_terms: D000293:Adolescent; D000328:Adult; D018798:Anemia, Iron-Deficiency / Q000188:drug therapy* / Q000503:physiopathology; D001644:Bifidobacterium / Q000187:drug effects* / Q000254:growth & development; D018592:Cross-Over Studies; D004311:Double-Blind Method; D005243:Feces / Q000737:chemistry* / Q000382:microbiology; D005260:Female; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007444:Inulin / Q000008:administration & dosage*; D007503:Iron Isotopes; D019266:Iron, Dietary / Q000493:pharmacokinetics*; D019344:Lactic Acid / Q000032:analysis; D016014:Linear Models; D054892:Metagenome / Q000187:drug effects; D055815:Young Adult
chemical_list: D007503:Iron Isotopes; D019266:Iron, Dietary; D019344:Lactic Acid; D007444:Inulin