What is an insoluble fiber supplement?

Insoluble fiber supplements traditionally come from “functional” fibers, which is a type of fiber that is isolated from plants or animals, with human health benefits, according to WebMD. These substances are available in a medley of options including powders, oil and chewable tablets.

WebMD defines insoluble fiber as a "gut-healthy" source of fiber that does not dissolve in water, which enables it to pass through the digestive system intact. These fibers feature a laxative effect that helps thwart constipation and are predominately found in whole grains, fruits and vegetables such as cucumbers, green beans, broccoli, onions, grapes, zucchini and more, according to WebMD.