The National Cancer Institute recommends that Americans double the average amount of fiber they eat to 20 to 30 grams a day -- but not to exceed 35. Essentially that means eating three to five servings of whole-grain breads and cereal, three servings of vegetables and two to three servings of fruit per day. Here are some guidelines from NCI to give you an idea of where the fiber is -- and isn't.

RICH SOURCES OF DIETARY FIBER (4 or more grams of fiber per serving; those foods marked with * have 6 or more grams of fiber per serving)

Cereals: All Bran-Extra Fiber*, Fiber-One*, All Bran Fruit & Almonds*, All Bran*, 100 percent Bran*, Bran Buds*, Corn Bran, Bran Chex, Cracklin' Oat Bran, Bran Flakes, Raisin Bran.

Legumes: kidney beans, navy beans, lima beans.

Fruits: Dried prunes.

MODERATELY RICH SOURCES OF DIETARY FIBER (1 to 3.9 grams of fiber per serving)

Breads, grains, cereals and pasta: whole-wheat spaghetti, Most, wheat germ, Shredded Wheat, Wheat Chex, Total, Wheaties, cooked oatmeal, Grapenuts, whole-wheat bread, Cheerios, regular spaghetti, brown rice, air-popped popcorn.

Legumes (cooked) and nuts: lentils, peanuts, almonds.

Vegetables: green peas, corn, parsnips, potatoes, brussels sprouts, carrots, broccoli, cooked spinach, sweet potatoes, string beans, turnips, bean sprouts, tomatoes, kale, red and white cabbages, summer squash, raw spinach, cauliflower, celery, asparagus.

Fruits: apples, pears, raisins, strawberries, oranges, bananas, blueberries, dried dates, peaches, fresh apricots, grapefruits, dried apricots, cherries, pineapples, cantaloupes.

LOW SOURCES OF DIETARY FIBER (less than 1 gram of fiber per serving)

Breads and cereals: white bread, cornflakes, white rice, Rice Krispies.

Vegetables: lettuce, mushrooms, onions, green peppers.

Fruits: grapes, watermelons.

Fruit juices: papayas, grapes, grapefruits, oranges, apples.