Which type of fibre keeps stools soft--soluble or insoluble?

Insoluble: Insoluble fibber adds bulk and keeps stool soft.

Fiber: Soluble. Insoluble adds bulk to stool such as salads. A good dietary fiber is flax seeds. Some farmers markets, health food stores. Also helps in reducing cholesterol excreted in bile by reducing its reabsortion i terminal ileum to a minor degree. If have cholesterol problem do not depend on it by itself. It's an adjunct not treatment . Good for bowel health.