Fiber

Introduction

Dietary fiber is a general term that refers to a wide variety of compounds found in plants that are resistant to the digestive enzymes produced by humans. Because dietary fiber is resistant to digestive enzymes, it is not broken down or absorbed, which means it does not provide calories or energy to the body. In general, dietary fibers are various forms of complex carbohydrates that have differing abilities to swell by absorbing water into their structural matrix.

There are two types of fibers, soluble and insoluble. Fibers that can actually dissolve in water, such as pectin, gums, and psyllium, are referred to as soluble fiber. Soluble fiber mixes with water, turning into a gel-like substance in the process as it passes through the gastrointestinal tract. Insoluble fibers or roughage cannot dissolve in water but can absorb water. This causes them to swell, making them good bulking agents, which speeds up transit time and improves elimination. Examples of insoluble fibers are cellulose, hemicelluloses, and lignins.

A lack of fiber is usually the result of poor food choices, which results in a diet that is deficient in fiber-containing foods. Consuming a diet lacking in fiber increases the risk of developing gastrointestinal problems such as constipation, diverticular disorders, and alterations in glycemic control. It has been recommended that Americans should strive to achieve a total dietary fiber intake of 25 to 30 grams/day, which should preferentially come from foods, not supplements. However, dietary surveys indicate that dietary fiber intake among adults in the United States averages about 15 grams/day, or approximately half the recommended amount. (1)

In general, dietary fiber and fiber supplements are not digested or absorbed by humans. Foods that are rich in soluble fiber include apples, citrus fruits, pears, carrots, onions, sweet potatoes, squash, legumes, and grains such as barley, oats, oat bran, and oatmeal. Foods high in insoluble fiber include whole-wheat breads, wheat cereals, wheat bran, rye, rice, barley, most other grains, potatoes, flaxseeds, and vegetables such as cabbage, beets, carrots, Brussels sprouts, turnips, and cauliflower.

Dosage Info

Dosage Range

The variety of different kinds of fiber supplements available makes it difficult to suggest dosages.

Most Common Dosage

The variety of different kinds of fiber supplements available makes it difficult to suggest dosages.

Dosage Forms

Tablets, capsules, and bulk powder.

Interactions and Depletions

Interactions

Reported Uses

In general, high fiber diets are associated with significantly reduced risks of cardiovascular disease, (2) cancer, (3) , (4) and many other illnesses. (5) Soluble fibers have a moderate cholesterol-lowering effect (6) and they also help regulate blood sugar levels. (7) In diabetes, type 1, a diet high in fiber was reported to improve glycemic control and reduce the number of hypoglycemic events experienced. (8) Dietary fiber intake has been associated with a lower risk of type 2 diabetes. (9) Patients with type 2 diabetes who were consuming 50 grams of fiber daily were compared to patients following the American Diabetes Association’s recommendation of 24 grams of fiber daily. After 6 weeks, patients on the higher fiber diet had substantially better control of blood glucose, insulin, and blood lipids. (10) In another study, a group of men with type 2 diabetes, taking psyllium twice daily experienced significant improvements in blood glucose and lipid values compared to a control group taking a placebo. (11)

Fiber is also one of the elements in a program used to treat constipation along with extra hydration and exercise. (12) In fact, studies have indicated that diets that are low in fiber are associated with constipation in both children (13) and in the elderly. (14) Fiber has also been recommended as a dietary addition in therapies with patients who are being treated for hemorrhoids (15) as well as for diverticulosis. (16)

High fiber diets may help protect against obesity according to the results of a study that followed young adults for a period of ten years. Individuals who consumed the least dietary fiber gained 8 pounds more over the 10-year period compared to individuals who consumed at least 21 grams of fiber daily. (17)

The results of numerous studies indicate that people and/or cultures with high fiber diets reduce their risk of colorectal cancer by more than 30%. (18) , (19) When the non-digestible fibers reach the colon, anaerobic bacteria degrade them in a process called fermentation. This process produces byproducts known as short-chain fatty acids, which help maintain proper acid/base balance in the colon and for this reason may play a role in the prevention of colorectal cancer. (20)

Toxicities & Precautions

Introduction

[span class=alert]Be sure to tell your pharmacist, doctor, or other health care providers about any dietary supplements you are taking. There may be a potential for interactions or side effects.[/span]

General

This dietary supplement is considered safe when used in accordance with proper dosing guidelines.

Side Effects

Side effects are possible with any dietary supplement. Large doses of this dietary supplement over a short period of time may cause gas, bloating and intestinal cramps. These symptoms are almost always reduced by backing off the dose and then gradually increasing the amount of fiber. Tell your doctor if these side effects become severe or do not go away.

Pregnancy / Breast Feeding

This dietary supplement should not be used if you are pregnant or breast-feeding an infant without first consulting a physician.To date, the medical literature has not reported any adverse effects related to fetal development during pregnancy or to infants who are breast-fed. Yet little is known about the use of this dietary supplement while pregnant or breast-feeding. Therefore, it is recommended that you inform your healthcare practitioner of any dietary supplements you are using while pregnant or breast-feeding.

Age Limitations

To date, the medical literature has not reported any adverse effects specifically related to the use of this dietary supplement in children. Vitamins and minerals are an essential part of proper growth and development. Talk to your healthcare professional about the appropriate use of vitamins and minerals in children. Do not use any vitamin or mineral in children under 2 years of age unless first discussed with your healthcare professional.

References

  1. View Abstract: Alaimo K, McDowell M, Briefel R, Bischof A, Caughman C, Loria C, Johnson C. Dietary intake: vitamins, minerals and fiber of persons age two months and over in the United States: third National Health and Nutrition Examination Survey: phase 1, 1988-91. Advance Data. 1994;258:1-28.
  2. View Abstract: Negri E, La Vecchia C, Pelucchi C, Bertuzzi M, Tavani A. Fiber intake and risk of nonfatal acute myocardial infarction. Eur J Clin Nutr. Mar2003;57(3):464-70.
  3. View Abstract: Slattery ML. Plant foods, fiber, and rectal cancer. Am J Clin Nutr. Feb2004;79(2):274-81.
  4. View Abstract: Mattisson I. Intakes of plant foods, fibre and fat and risk of breast cancer--a prospective study in the Malmo Diet and Cancer cohort. Br J Cancer. Jan2004;90(1):122-7.
  5. View Abstract: Kromhout D, Bosschieter EB, de Lezenne Coulander C. Dietary fibre and 10-year mortality from coronary heart disease, cancer, and all causes: the Zutphen Study. Lancet. 1982;1:518-522.
  6. View Abstract: Fernandez ML. Soluble fiber and nondigestible carbohydrate effects on plasma lipids and cardiovascular risk. Curr Opin Lipidol. Feb2001;12(1):35-40.
  7. View Abstract: Ou S, Kwok K, Li Y, Fu L. In vitro study of possible role of dietary fiber in lowering postprandial serum glucose. J Agric Food Chem. Feb2001;49(2):1026-9.
  8. View Abstract: Giacco R, Parillo M, Rivellese AA, et al. Long-term dietary treatment with increased amounts of fiber-rich low-glycemic index natural foods improves blood glucose control and reduces the number of hypoglycemic events in type 1 diabetic patients. Diabetes Care. Oct2000;23(10):1461-6.
  9. View Abstract: Schulze MB, Liu S, Rimm EB, Manson JE, Willett WC, Hu FB. Glycemic index, glycemic load, and dietary fiber intake and incidence of type 2 diabetes in younger and middle-aged women. Am J Clin Nutr. Aug2004;80(2):348-56.
  10. View Abstract: Chandalia M, Garg A, Lutjohann D, et al. Beneficial effects of high dietary fiber intake in patients with type 2 diabetes mellitus. N Engl J Med. May2000;342(19):1392-8.
  11. View Abstract: Anderson JW, Allgood LD, Turner J, et al. Effects of psyllium on glucose and serum lipid responses in men with type 2 diabetes and hypercholesterolemia. Am J Clin Nutr. Oct1999;70(4):466-73.
  12. View Abstract: Soffer EE. Constipation: an approach to diagnosis, treatment, referral. Cleve Clin J Med. Jan1999;66(1):41-6.
  13. View Abstract: Roma E, Adamidis D, Nikolara R, et al. Diet and chronic constipation in children: the role of fiber. J Pediatr Gastroenterol Nutr. Feb1999;28(2):169-74.
  14. View Abstract: Kovach T. Managing geriatric chronic constipation. Home Healthc Nurse. Sep1992;10(5):57-8.
  15. View Abstract: Otto P, Otto JU. Hemorrhoidal diseases. Schweiz Rundsch Med Prax. Nov1994;83(44):1225-8.
  16. View Abstract: Eggenberger JC. Diverticular Disease. Current treatment options in gastroenterology. Dec1999;2(6):507-516.
  17. View Abstract: Ludwig DS, Pereira MA, Kroenke CH, et al. Dietary fiber, weight gain, and cardiovascular disease risk factors in young adults. JAMA. Oct1999;282(16):1539-46.
  18. View Abstract: Jansen MC, Bueno-de-Mesquita HB, Buzina R, et al. Dietary fiber and plant foods in relation to colorectal cancer mortality: the Seven Countries Study. Int J Cancer. Apr1999;81(2):174-9.
  19. View Abstract: Howe GR, Benito E, Castelleto R, et al. Dietary intake of fiber and decreased risk of cancers of the colon and rectum: evidence from the combined analysis of 13 case-control studies. J Natl Cancer Inst. 1992;84:1887-1896.
  20. View Abstract: Scheppach W, Luehrs H, Menzel T. Beneficial health effects of low-digestible carbohydrate consumption. Br J Nutr. Mar2001;85(Suppl 1):S23-30.