Fibers are long, thin threads of material, like hair
Dietary fiber is a plant-based nutrient that is sometimes called roughage or bulk. It is a type of carbohydrate but, unlike other carbs, it cannot be broken down into digestible sugar molecules. Therefore, fiber passes through the intestinal tract relatively intact. However, on its journey, fiber does a lot of work.
The term “dietary fiber” refers to the indigestible parts of plant-based foods. In other contexts, “fiber” might refer to plant-based cloth, but when speaking of nutrition, the terms “fiber” and “dietary fiber” are often interchangeable.
Fiber is important to digestion and regularity, weight management, blood sugar regulation, cholesterol maintenance and more, according to Paige Smathers, a Utah-based dietitian. It has also been linked to longevity and decreasing the risk of cancer.
The Institute of Medicine has set a recommended daily amount (RDA) for fiber intake. Men ages 50 and younger should consume 38 grams of fiber per day, and men 51 and older should consume 30 grams. Women ages 50 and younger should consume 25 grams per day, while their older counterparts should have 21 grams. Most Americans do not consume enough fiber, according to the institute.
Soluble fiber vs. insoluble fiber
Fiber can be put into two categories: soluble and insoluble fiber, according to Colorado State University.
Simply put, Smathers said, soluble fiber, such as pectin, gum and mucilage, dissolves in water; insoluble fiber, such as hemicellulose, cellulose and lignin, does not. In the body, soluble fiber dissolves and becomes a gel-like substance. Insoluble fiber mostly retains its shape while in the body.
Both soluble and insoluble fibers have important benefits, according to Smathers. Soluble fiber is known to help decrease blood glucose (blood sugar) levels. It also helps lower blood cholesterol.
Insoluble fiber, on the other hand, speeds up the passage of food through the digestive system. This helps maintain regularity and prevent constipation. It also increases fecal bulk, which makes stools easier to pass.
Most plant-based foods contain both soluble and insoluble fiber, but the amounts of each vary in different foods, according to the Mayo Clinic. Good sources of soluble fiber include beans, lentils, oatmeal, peas, citrus fruits, blueberries, apples and barley. Good sources of insoluble fiber include foods with whole-wheat flour, wheat bran, brown rice, cauliflower, potatoes, tomatoes and cucumbers. Some foods, like nuts and carrots, are good sources of both types of fiber.