Study design and interventions
v5.83
This was a 4-arm parallel, double-blind, randomized, placebo-controlled trial lasting 5 wk, segregated into a 1-wk run-in and 4-wk intervention phase. The study length (5 wk) was chosen to capture initial day-to-day fluctuations in gastrointestinal habits prior to commencement of intervention, combined with methods previously documented in several mood state and/or gut microbiota supplementation studies [The ITF used was OF (Orafti P95, DP 3-9, average DP 4; BENEO-Orafti). The other test product was 2’FL. 2’FL is an HMO produced commercially using metabolically engineered organisms. 2’FL (96%–98% pure) is a fucosylated HMO composed of L-fucose, D-galactose, and D-glucose and was supplied by BENEO-Orafti. The comparator (placebo) product was maltodextrin, a readily digestible carbohydrate, which consists of varying chains of D-glucose primarily linked by α-(1,4)-linkages of various chain length. To maintain blinding, interventions were packaged in equal weight sachets (sachets A/B = either 8 g OF or maltodextrin and sachets 1/2 = either 2 g maltodextrin or 2’FL) with unique randomization codes by a research assistant not otherwise involved in the study. A random sequence was created utilizing the software RandList Version 1.5. Two grams of 2’FL was the selected dosage based on results of our previous in vitro batch culture fermentations [Stool, urine, and saliva samples were collected from volunteers as the first urine, stool, and saliva samples after waking at the start (Day 0 [D0]) and the end (Day 28 [D28]) of the intervention phase. Volunteers were also asked to complete self-reported mood state and sleep questionnaires at the start and again at the end of the 4-wk intervention phase. No intervention was given until baseline samples and self-reported questionnaires had been completed. Volunteers were instructed to consume both of their assigned sachets once per day for 4 wk in the morning in water just after or with breakfast resulting in a total daily intervention intake of 10 g. Compliance with consumption of the interventions was assessed by completion of a daily online check-in diary. Participants were considered compliant if they consumed >95% of the supplied supplements. Volunteers were told to not alter their diet or fluid intake during the trial and were asked to record their dietary intake for 3 consecutive days at the start (D0, D1, D2) and end (D26, D27, D28) of the intervention phase into specified diary pages via supplied links. Nutrient intakes (total kcals, protein, fat, saturated fat, total carbohydrates, total sugar, and fiber) were calculated using Nutritics v5.83 [Data were collected and managed using Research Electronic Data Capture (REDCap) electronic data capture tools hosted at the University of Reading [