Nutrition

Fiber

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Fiber, Dietary Fiber, Roughage, Bulk Laxative, Bulk-Forming agents, Psyllium, Metamucil, Methylcellulose, Citrucel, Polycarbophil, Fibercon

  • Indications
  1. Constipation
  2. Irritable Bowel Syndrome
  3. Diverticulosis
  4. Hemorrhoids
  5. Hypercholesterolemia
  6. Obesity
  • Physiology
  1. Dietary Fiber improves stool bulk and transit time
  2. Dietary Fiber lowers serum Cholesterol
  • Precaution
  1. Fiber content listed below is approximate
  2. Various texts list different fiber per serving
  • Adverse Effects
  1. Use with 64 oz/day (>1.8 Liters/day) non-caffeinated fluid
  2. Poorly tolerated in atonic colon (e.g. Megacolon)
  3. Gas (bloating, Abdominal Distention, Flatulence)
    1. More common if started too quickly with high dosing
    2. Reduced by gradually increasing fiber intake to 225-30 grams per day
    3. Side effects more likely with dyssynergic Defecation
    4. Side effects are more common with insoluble fiber
      1. Insoluble fiber examples include (Methylcellulose, Citrucel, wheat bran)
      2. In contrast, soluble fiber (psyillium, Metamucil, oat bran) is associated with less gas
  • Drug Interactions
  1. May interfere with absorption of medications
    1. Do not take medications at the same time as Psyllium
    2. Space Psyllium several hours apart from medications
  2. Agents known to be affected
    1. Carbamazepine (Tegretol)
      1. Etman (1995) Drug Dev Ind Pharm 21:1901-6 [PubMed]
    2. Lithium
      1. Perlman (1990) Lancet 335:416 [PubMed]
  • Preparations
  • Dietary Fiber Sources
  1. Whole grain cereals or breads
    1. All-Bran or 100% Bran Cereal (>8 grams per serving)
    2. Wheaties (2.6 grams per serving)
    3. Shredded Wheat (6 grams per serving)
    4. Grits (5 grams per serving)
    5. Grape-nuts (5 grams per serving)
  2. Fresh fruits
    1. Raspberries (4.5 grams per serving)
    2. Fruits with 1-3 grams fiber per serving
      1. Apple with peal
      2. Orange
      3. Peach
      4. Pear
      5. Strawberries
    3. Fruits with negligible fiber
      1. Grape-fruit has only 0.6 grams fiber per serving
      2. Apple juice has no fiber content
  3. Vegetables (raw better than cooked)
    1. Beans (>8 grams per serving)
      1. Kidney beans
      2. Lima beans
      3. Navy beans
      4. Baked beans
    2. Peas (6 grams per serving)
    3. Corn on the cob (6 grams per serving)
    4. Parsnips (6 grams per serving)
    5. Lentils (4 grams per serving)
    6. Broccoli (3 grams per serving)
    7. Baked Potato with skin (3 grams per serving)
    8. Other vegetables with 1-2 grams fiber per serving
      1. Beets
      2. Cabbage
      3. Carrots
      4. Celery
      5. Corn
      6. Squash
      7. Green beans
      8. Turnips
  4. Other sources
    1. Whole wheat bread (1.3 grams per serving)
  • Bulk-Forming agents
  1. Psyllium (Metamucil): 10 grams per day
    1. Dose: 1-2 tsp in 8 ounces of water or juice PO tid
  2. Methylcellulose (Citrucel): 6 grams per day
    1. Dose: 2 grams in 8 ounces liquid PO tid
  3. Calcium Polycarbophil (Fibercon)
    1. Dose: Two 625 mg tablets PO tid
    2. Synthetic bulk agent containing polyacrylic acid
  4. Dietary sources with as much fiber at 10% of cost
    1. Wheat bran, oat bran or all-bran cereal
    2. Lima, Navy, Kidney and baked beans
  • References
  1. Brody (1981) Nutrition Book, p. 147
  2. Cheskin in Barker (1995) Ambulatory Medicine, p. 479