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The Facts About Fiber

Fiber Types

There are two types of dietary fiber: soluble and insoluble. “Both are important and work in different ways,” says Baton Rouge nutrition expert Hilary Shaw, RD, LPC.

You’ll want to make choices on the type of fiber you eat depending on what you're experiencing. “Soluble fiber helps diarrhea by absorbing water and adding bulk to stools. Insoluble fiber, which is not digestible, may help with constipation but make diarrhea worse," Shaw says.

Which is which? In fruits, vegetables, and whole grains, generally the outside (skin) is insoluble (also known as “roughage”); the soft inside is soluble.

Soluble fiber has the added benefit of helping you lower your cholesterol and control your blood sugar.

Soluble fiber:

  • Oats
  • Beans, peas, and other legumes
  • Sweet potatoes
  • Apples
  • Mangos
  • Plums
  • Berries
  • Peaches
  • Kiwi
  • Figs

Insoluble fiber:

  • The skins of fruit
  • The skins of beans
  • Potato skin (especially when it’s crispy, but avoid French fries, which are high in fat)
  • whole wheat, wheat bran, and whole grain cereal products
  • brown rice
  • seeds
  • broccoli
  • spinach
  • carrots
  • cucumbers
  • celery
  • lettuce
  • zucchini
  • tomatoes

While you'll likely have more options to add fiber to your diet when you make meals at home, there are easy ways to get it on the go. Davis recommends these choices when placing your order:

For Breakfast:

  • Oatmeal
  • Oat bran muffin
  • Yogurt with granola

For Lunch or Dinner:

  • Chili with beans topped with lettuce and tomato; add lettuce and tomato to whenever possible.
  • Skip the white bread with your sandwich and go for a whole wheat bun, wrap, or pita instead.
  • Swap the meat for a bean patty.
  • Order a side salad, fruit, or small baked potato instead of fries.

Fiber Supplements

In some cases, your doctor may recommend supplemental fiber. When possible, though, it’s best to get your fiber from unprocessed food sources.

Fiber supplements lose some of their natural ingredients during processing, says gastroenterologist Dang Nguyen, MD, of St. Luke’s Medical Center in Houston. “Natural fiber from fruits and vegetables may help a person stay full longer, too.”

Check with your doctor before taking fiber supplements, as people with certain medical conditions may need to avoid them.

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Reviewed on October 13, 2013

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