Effect of Inulin on Iron Absorption in Humans

Inulin Modifies Gut Microbiota, Fecal Lactate Concentration and Fecal pH But Does Not Influence Iron Absorption in Women With Low Iron Status

Prebiotics are non-digestible food ingredients that beneficially affect the host by selectively stimulating the growth or activity of species in the colon that can improve host health.

Inulin-type fructans (inulin and oligofructose) are natural food ingredients with prebiotic activity. Fermentation of inulin and oligofructose by lactic acid producing bacteria results in an increase in bacterial biomass and the production of SCFA (acetate, propionate and butyrate), lactic acid and the gases CO2 and H2. They are naturally present in significant amounts in several vegetables such as garlic, artichoke, onion, asparagus, leek and wheat (1-4%). Based on consumption data, the daily intake of inulin in Europe varies between 3.2 and 11.3g mainly from wheat (2-7.8g/d). However, this might have changed recently since inulin and oligofructose are used by the food industry either as sucrose and fat replacements or due to their health benefits for the human host.

Several human absorption studies evaluated the effect of inulin/oligofructose on mineral absorption. It was shown that calcium and magnesium absorption was positively influenced. Until now, the positive effect on iron absorption was only shown in animals. The influence on human iron absorption was investigated twice. Both studies reported no effect of inulin/oligofructose on iron absorption, but this was most likely due to poorly conceived study designs.

The aim of the present study is to demonstrate that inulin consumption over several weeks can lead to enhanced iron absorption in humans under optimized conditions.

Study Overview

• Status: Completed
• Conditions: Gut Bacteria; Iron Absorption
• Intervention / Treatment: Dietary supplement: inulin; Dietary supplement: maltodextrin

• Study Type: Interventional
• Enrollment (Actual): 32
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Switzerland
  • Zürich, Switzerland, 8092
    • ETH

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 40 years (Adult)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: Female

Description

Inclusion Criteria:

• non-pregnant, non-lactating women
• between 18 and 40 years
• below 65kg

Exclusion Criteria:

• metabolic, chronic and gastro-intestinal disease
• long-term medication
• blood donation within 6 month before the study-

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Crossover Assignment
• Masking: Double

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: inulin	Dietary supplement: inulin; 20g/day for 4 weeks
Placebo Comparator: maltodextrin	Dietary supplement: maltodextrin; 20g/day for 4 weeks

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Time Frame
impact of inulin on iron absorption from standardized test meals, measured in humans by stable iron isotope technique	3 month

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
impact of inulin on the concentration of gut microbiota (bifidobacteria and total bacteria), SCFA and fecal pH in human subjects	Concentration of bifidobacteria, total bacteria, SCFA (acetate, propionate, butyrate, formate), lactate, and pH will be measured (in the fecal samples of study participants) and compared between baseline, inulin period and placebo period. The pH of fecal sqamples will be measured using a digital pH meter. HPLC measurements will be done for the determination of SCFA and lactate. DNA amplification and detection will be done by quantitative PCR.	3 month

Collaborators and Investigators

• Sponsor: Swiss Federal Institute of Technology
• Investigators: Principal Investigator: Richard Hurrell, Prof. Dr., ETH Zurich

Publications and helpful links

General Publications

• Petry N, Egli I, Chassard C, Lacroix C, Hurrell R. Inulin modifies the bifidobacteria population, fecal lactate concentration, and fecal pH but does not influence iron absorption in women with low iron status. Am J Clin Nutr. 2012 Aug;96(2):325-31. doi: 10.3945/ajcn.112.035717. Epub 2012 Jun 27.

Study record dates

Study Major Dates

• Study Start: August 1, 2011
• Primary Completion (Actual): November 1, 2011
• Study Completion (Actual): January 1, 2012

Study Registration Dates

• First Submitted: November 9, 2011
• First Submitted That Met QC Criteria: November 29, 2011
• First Posted (Estimate): December 1, 2011

Study Record Updates

• Last Update Posted (Estimate): June 7, 2013
• Last Update Submitted That Met QC Criteria: June 6, 2013
• Last Verified: June 1, 2013

More Information

Terms related to this study

• Other Study ID Numbers: INOL