Efficacy and findings of a blinded randomized reintroduction phase for the low FODMAP diet in Irritable Bowel Syndrome

BACKGROUND AND AIMS

The efficacy of a low fermentable oligo-, di-, monosaccharides and polyols (FODMAP) diet in Irritable Bowel Syndrome (IBS) is well established. After the elimination period, a reintroduction phase aims to identify triggers. We studied the impact of a blinded reintroduction using FODMAP-powders to objectively identify triggers and evaluated the effect on symptoms, quality of life (QoL), and psychosocial co-morbidities.

METHODS

Responders to a 6-week low-FODMAP diet, defined by a drop in IBS-symptom severity score (IBS-SSS) compared to baseline, entered a 9-week blinded randomized reintroduction phase with 6 FODMAP powders (fructans, fructose, galacto-oligosaccharides, lactose, mannitol, sorbitol) or control (glucose). A rise in IBS-SSS (≥50 points) defined a FODMAP-trigger. Patients completed daily symptom diaries and questionnaires for QoL and psychosocial co-morbidities.

RESULTS

In 117 recruited IBS patients, IBS-SSS improved significantly after the elimination period compared to baseline (150±116 vs 301±97, P < .0001, 80% responders). Symptom recurrence was triggered in 85% of the FODMAP powders, by an average of 2.5±2 FODMAPs/patient. The most prevalent triggers were fructans (56%) and mannitol (54%), followed by galacto-oligosaccharides, lactose, fructose, sorbitol, and glucose (respectively 35%, 28%, 27%, 23%, and 26%) with a significant increase in abdominal pain at day 1 for sorbitol/mannitol, day 2 for fructans/galacto-oligosaccharides and day 3 for lactose.

CONCLUSION

We confirmed the significant benefit of the low-FODMAP diet in tertiary care IBS. A blinded reintroduction revealed a personalized pattern of symptom recurrence, with fructans and mannitol as the most prevalent, and allows the most objective identification of individual FODMAP-triggers; Clinicaltrial.gov number: NCT04373304.

On-site characterization of humic-rich hydrocolloids and their metal loading by means of mobile size-fractionation and exchange techniques

Humic-rich hydrocolloids and their metal loading in selected German bog-waters have been characterized by a novel on-site approach. By use of an on-line multistage ultrafiltration (MST-UF) unit equipped with conventional polyethersulfone (PES)-based flat membranes (nominal cut-off 0.45, 0.22, and 0.1 microm, or 100, 50, 10, 5, 3 kDa) the hydrocolloids could be fractionated on-site in both sub-particulate and macromolecular size ranges. Characterization (dissolved organic carbon (DOC), metals) of the colloid fractions obtained this way was performed off-site by use of conventional instrumental methods (carbon analyzer, AAS, ICP-OES, and TXRF (total reflection X-ray fluorescence)). Major DOC fractions of the hydrocolloids studied were found to be in the size range <5 kDa. The assessed metals (Al, Cu, Fe, Mn, Pb, and Zn) were, however, predominantly enriched in the macromolecular and sub-particulate range, depending on the metal and the sample, respectively. In addition, metal species bound to these hydrocolloids were kinetically characterized on-site by use of competitive ligand (EDTA (ethylenediaminetetraacetate)) and metal (Cu(II)) exchange; the EDTA complexes formed and the metal ions exchanged were separated by means of a small time-controlled tangential-flow UF unit (cut-off 1 kDa). Bound metal fractions, in particular Al and Fe, reacted only slowly (500 to 1000 min) with EDTA; the conditional availability was 60-99%, depending on the hydrocolloid. In contrast, the Cu(II) exchange of colloid-bound metal species approached equilibrium within 5-10 min, with characteristic exchange constants, Kex, of the order of 0.01 to 90 for the metals (Fe<Al<Zn<Mn approximately/= Ca approximately/= Mg). The results were clearly dependent on the water investigated. Thus detailed information on the conditional kinetic and thermodynamic stability of colloid-bound metal species could be obtained from competitive EDTA and Cu(II) exchange under on-site conditions.