Plant materials that are indigestible to humans are a complex carbohydrate known as dietary fiber. Our bodies need roughage to properly digest food and eliminate waste because the bulky substance cleans the colon as it makes its way through our digestive tract. Dietary fiber comes from vegetables, fruit, grain, and legumes.
The two types of dietary fiber are soluble and insoluble. Soluble fiber dissolves in water, like the pectin found in fruit. Insoluble fiber, such as cellulose from grain, doesn't dissolve in water. Examples of soluble fiber are many vegetables, barley, oatmeal, rye, and fruits like peaches, grapes, berries, and pears. It's important to eat the skin of fruits like apples, since that is where most of the fiber resides. Whole grains, pasta, bran, brown rice, seeds, bran, beans, and a few vegetables like carrots and celery, provide insoluble fiber.
Proper amounts of dietary fiber improve health in ways other than digestion. Studies have shown that fiber seems to lower cholesterol, in combination with a balanced diet. There is also an inexplicable link between a diet high in fiber and a lowered risk of heart disease. In the stomach, fiber seems to affect the speed with which sugar enters the bloodstream. This means our blood sugar levels stay more consistent, our insulin doesn't work as hard, and we benefit from a reduced risk of developing diabetes.
Since fiber is not technically a nutrient, there is no Recommended Daily Allowance (RDA). However, health care experts have declared we need .7-1.2 oz (20 - 35 grams) of fiber per day. Yet Americans only average 1/2 oz (15 grams) a day. Fresh food is the best source of fiber because it contains other important vitamins. If fresh food is not available, dietary supplements of fiber will suffice. A gradual increase, over several weeks, in your fiber intake will ensure you don't suffer any discomfort. In combination with a diet low in sugar, fat, and cholesterol, roughage improves many aspects of health.