2.1. Participant Recruitment

The inclusion criteria for participation were being an adult (18 to 65 years), having a body mass index ≤35, 1 to 3 reported bowel movements per week, being able and willing to provide blood and stool samples, not taking fiber supplements or medications for constipation, habitually consuming a routine diet that has 50% or less of the recommended dietary fiber intake of 25 g and 38 g per day for women and men, and have access to the internet for providing logs of bowel movements, GI sensations, general health, and diet histories. Specific exclusion criteria included diabetes, existing or history of recurring GI disorders, including irritable bowel syndrome (IBS) and inflammatory bowel disease (IBD), antibiotic use within 4 weeks of starting the study, pregnancy or wishing to become pregnant, breastfeeding, abuse of alcohol or non-prescription drugs. A total of 104 volunteers were enrolled and 97 completed the study. The study population was 80% women (Table 1), corresponding with 4-fold more women than men suffering from irregularity [13].

Baseline demographics (means and standard deviations) of the adult participants assigned to the oligofructose (OF) group or maltodextrin (MD) group (placebo).