There are two types of fiber: soluble and insoluble. Soluble fiber is found in nuts and seeds; fruits like apples, bananas, and berries; and in legumes and certain grains, like oat bran and barley. Insoluble fiber is in vegetables, wheat, and other whole grains. Both aid in healthy digestion but play different roles in the process.
Registered dietitian Amy Shapiro, M.S., R.D., CDN previously told mindbodygreen that soluble fiber “dissolves into a gel-like substance” in water and helps to collect and remove toxins and cholesterol from the body. Insoluble fiber, on the other hand, does not dissolve—it stays intact as it moves through the digestive system. While, like soluble fiber, it ushers out toxins and bad cholesterol, registered dietitian Ella Davar, R.D., CDN, CHC tells mindbodygreen that it also speeds up digestion.
“Both types of fiber are essential for gut health, but the difference [between soluble and insoluble fiber] is that the insoluble fiber speeds the passage of foods through the stomach and intestines and adds bulk to the stool,” Davar explains. The more water in the stool, the easier it passes.