Table 1.

PICOS criteria for inclusion and exclusion of observational studies and randomized controlled trials

	Criteria
Parameter	Observational studies	Randomized controlled trials
Population	Human participants, both healthy and diseased (eg, individuals with type 2 diabetes mellitus)	Human participant, both healthy and diseased (eg, individuals with type 2 diabetes mellitus)
Intervention	Dietary fiber intake	Whole-diet fiber interventions or fiber supplements
Comparator	Low dietary fiber intake	Habitual or sham diet, low-fiber control diet, or placebo (eg, maltodextrin)
Outcomes	Depressive and anxiety outcomes	Depressive and anxiety outcomes