Figure 1.

Illustration of the study design, a 3 × 3 randomized crossover intervention pilot study comparing the effects of three interventions, calcium supplementation, inulin supplementation, and combined calcium and inulin supplementation, on gut microbiome parameters. Participants (n = 9) were randomized into a sequence of three four-week intervention periods interspaced by one-week washout periods. Fecal and blood samples were collected at the start and end of each intervention period and after the last washout period. Dietary recalls were collected at the middle of each study period. Behavior and lifestyle questionnaires were collected at the study start and end, and before and after each intervention period.