The impact of an intrinsic dried vegetable fibre on gut microbiota, bowel function and glucose homeostasis markers.

The study was a two-arm randomized, placebo-controlled, investigator-blinded parallel trial in 55 subjects at risk of type 2 diabetes. The Medical Ethical Review Committee Wageningen University (METC-WU nr. 17/25) approved this study, it was carried out in according to the Declaration of Helsinki and was registered at the ISRCTN registry (ISRCTN39985847). The treatment product was an intrinsic multifibre product consisting of dried chicory roots, which are rich in native inulin enclosed within plant cell-walls made of pectin, cellulose and hemi-cellulose. Participants were eligible if they were between 40 and 75 year old and had either a fasting blood glucose level between 5.0 and 5.6 mmol/L with a high risk to develop type 2 diabetes (T2D) later in life as assessed by a diabetes risk score ≥ 9, or a fasting blood glucose level of 5.6 and 6.9 mmol/L (classified as prediabetes by the American Diabetes Association). The study consisted of three weeks intervention where subjects consumed 30 g of the multifibre product (n=28) per day or an iso-caloric placebo (maltodextrin, n=27). This study period was preceded by a two-week run-in period at half-dose and followed by a two week washout. At baseline, after the two-week run-in, after the three-weeks study and after the two-week washout faecal samples were collected to determine changes in gut microbiota composition. Samples were directly frozen at home and stored in the freezer (-20°C) until transport in frozen form to the laboratory and subsequent storage at -80°C. Besides gut microbiota composition, we also assessed faecal short-chain fatty acids a well as bowel function by monitoring stool softness and stool frequency, type 2 diabetes biomarkers by measuring circulating short-chain fatty acids, fasting insulin, fasting glucose and HOMA-ir in plasma (taken at baseline and after three weeks of 30g product intake) as well as changes in the coefficient of variation by continuous glucose measurement during baseline, run-in and the study period.