Another name for dietary fiber is roughage. The fiber in plant foods has two components, namely, soluble fiber and insoluble fiber. They provide good effects in different ways. Soluble fiber is absorbed into the system during the process of digestion and insoluble fiber eases out defecation and hence is equally important as the soluble fiber. The fiber changes the characteristics of the contents in GI tract and helps absorption of the nutrients. The soluble fiber consumes the water in the digestive system and becomes a viscous substance. Insoluble fiber acts as a bulk. However, the insoluble fiber from lignans can change the metabolism of the soluble fiber. Both these types of fiber are available in plant foods but in varying proportions, in accordance with the characteristics of the plant.
Every plant has some fiber, but for considering it as a source of dietary fiber, it should have high concentrations of fiber. Plants rich in fiber can be included in the diet directly or supplement foods can be made using them. Processed foods rich in fiber are also available. Plum is a good source of fiber. Its thick skin contains insoluble fiber and the juicy pulp inside has soluble fiber. Good amount of soluble fiber is available in legumes such as beans and peas, grains such as oats, barley, chia and rye, fruits such as plums, bananas and plums and vegetables such as carrots, Jerusalem artichokes, broccoli, onions, sweet potatoes and potatoes. The inner portion of pears and apples are rich in soluble fiber. The husk of psyllium seed contains soluble fiber.
Insoluble fiber is available in whole grain foods such as corn bran, wheat, nuts and seeds, skins of potato, flax seed, lignans, vegetables such as green beans, zuchhini, cauliflower, nopal and celery, and skins of some fruits. According to the Linus Pauling Institute lentils, peas, beans, wheat bran, prunes, Asian pear and quinoa are very rich in fiber. Blackberry and raspberry have good amounts of fiber.
Fiber supplements are used in treatment of many GI disorders. They are also useful in lowering the levels of cholesterol. They can reduce the risk of colon cancer. They help weight loss too. Soluble fiber supplements can treat abdominal discomfort and the symptoms of irritable bowel syndrome. Inflammatory bowel disease can be treated with soluble fiber products. You can include fiber supplements in your diet to treat the above bowel disorders effectively. Other sources of fiber supplements include vegetable gums which are mostly available as powdery substances. Vegetable gum fibers are also effective in treating irritable bowel syndrome. Guar gum and acacia senegal gum are some examples for vegetable gum fibers.
The US National Academy of Sciences recommends consumption of 20 – 35 grams of dietary fiber a day for adults. The American Dietetic Association (ADA) suggests that children should take fiber equivalent to their age plus 5 grams a day. There are no guidelines available for elderly people or people who have taken ill. If the indisposed persons have abdominal pain, constipation or vomiting, they should consult their doctor before venturing into a fiber diet. However, it is true that the foods rich in dietary fiber can offer several health benefits.