Dietary fiber, which people might sometimes call roughage or bulk, isn’t digested by your body. It passes through the stomach, intestines, and colon before it exits the body as stool. Only certain types of food contain fiber.
“Fiber is only found in plant foods — fruit, vegetables, grains, and legumes,” says Lynn Grieger, RDN, CDCES, a health, food, and fitness coach in Prescott, Arizona, and a medical reviewer for Everyday Health.
Soluble Fiber vs. Insoluble Fiber
Fiber comes in two forms: soluble and insoluble. Each has different effects on digestion.
- Soluble fiber: This type of fiber dissolves in water and absorbs it to create a gel that makes stool bulkier and easier to pass. “It also helps lower cholesterol and blood sugar levels,” says Grieger. Soluble fiber can be found in foods like beans, oats, apples, avocados, and okra.
- Insoluble fiber: This type can’t dissolve in water. It passes through your digestive system whole and keeps the contents of the digestive system moving along. “It helps promote optimum digestion,” says Grieger, who adds that insoluble fiber often produces more gas than soluble fibers do. Foods that contain insoluble fiber include whole-wheat flour, seeds, and the skins of fruits and veggies.
Not everyone will experience gas and bloating when they eat fiber, says Jennifer Bruning, RDN, a spokesperson for the Academy of Nutrition and Dietetics. “It depends on the person and what they eat, and what other foods they may be sensitive to,” she says. “Some people find some high-fiber foods make you more gassy, and others less so.”
Benefits of Dietary Fiber
Fiber offers a host of health benefits. A diet high in fiber helps lower cholesterol and improve blood sugar control. It also helps reduce your risk of developing these health problems: