There are two types of fiber: soluble and insoluble. Soluble fiber dissolves in water and forms a gel-like substance that slows down digestion. It can help lower cholesterol and regulate blood ...

Salt is soluble in water too. Substances that do not dissolve in water are called insoluble substances. When you mix sand or flour with water, they do not dissolve.

Insoluble fiber does not dissolve in water ... "Soluble fiber is a type of dietary fiber that dissolves in water to form a gel-like substance," says Lauren Manaker, MS, RDN.