Fiber supplements are products that are taken to increase the amount of fiber in the diet. Fiber is a type of carbohydrate that the body cannot digest, and it is found in plant-based foods such as fruits, vegetables, and whole grains. Fiber is important for digestive health, and it has been linked to a lower risk of heart disease, stroke, and type 2 diabetes. Some people take fiber supplements to relieve constipation or diarrhea. Others take them to help with weight loss. Fiber supplements are available in powder, capsule, and tablet form.