Grandma called it roughage, Madison Avenue calls it Fiber!, and health experts are calling for more. Yet all the name-calling doesn't amount to beans unless you know where to find fiber in foods -- and how to cook with it.

In many ways, fiber-padding your diet is a simple scheme. Eat more bran, whole-grain cereals, fruits, vegetables, whole-wheat products and legumes and you're set; there are lots of choices for a varied diet. And at the same time, you skim the fat and sodium out, too.

However, the typical American consumes in a day no whole-grain products and maybe one serving each of a fruit and vegetable, according to Elaine Lanza, a scientist in the diet and cancer branch of the National Cancer Institute. An easy remedy to double the fiber in that kind of diet: Trade in the white bread on the sandwich for whole wheat, eat a high-fiber breakfast cereal, a couple pieces of fruit and more vegetables daily, Lanza said. Sounds simple enough, although the catch is that there are two types of fiber.

At the risk of oversimplification, if you're concerned about cholesterol, eat the water-soluble fibers found mainly in legumes, oats, barley and citrus fruits. If you're looking for an inexpensive laxative and a possible protection against colon cancer, eat the insoluble fibers found mainly in wheat, vegetables and cereals (bran). Some foods, such as legumes, fruits and vegetables, contain both types of fiber, although they contain more of one type than the other.

Putting the complexities aside, perhaps the best recommendation for a general population is to get a healthy mixture of the two. That said, here's how to do it: How to Make the Switch -- Gradually

Obviously, if you normally eat Cocoa Puffs for breakfast and bologna on white for lunch, you don't want to overload tomorrow on bran cereal, lentil soup and chili. Plus, eating too much fiber may be just as bad an idea as not getting enough.

Instead of changing to whole-wheat bread, brown rice and whole-grain cereal all in the same week, start off by switching to whole-wheat bread, suggests local dietitian Ann Litt. Then make sure you have normal bowel movements before switching to the next high-fiber food.

And don't feel that you need to fill up on fiber at every meal; if you know you're having a fiber-filled lunch, the bran for breakfast may not be so essential, Lanza said. Where the Fiber Is -- and Isn't

There's no use trying to memorize exact fiber values in foods, said Lanza. Instead, think of it as this: The highest sources of fiber are the bran cereals (wheat, oat or corn), legumes and dried fruits. The moderates fall into whole-wheat breads and most all other fruits and vegetables. And the low sources are white breads, fruit juices and a few waterlogged fruits and vegetables.

Yet, in fine tuning the question of where the fiber is, there are some surprises. For one, rice is not a very high source. In fact, both brown rice and white rice are listed in the accompanying chart (see page E18) as low sources of food fiber. While brown rice does have five times as much fiber as white (1 gram versus .2 per 1/2 cup, cooked), brown rice is still not a high source of fiber, Lanza said.

For another, some salad vegetables that are eaten raw -- with the exception of carrots -- are actually low in fiber. Lettuce, after all, is about 96 percent water, Lanza said.

So if you think the lettuce and tomato on your sandwich fulfills your fiber for the day, think again. And if you load up your salad-bar plate with lettuce, tomatoes, peppers, mushrooms and onions, you're not getting as much fiber as you could. Instead, says Lanza, choose spinach, carrots, chickpeas, kidney beans and peas.

Juices have very little fiber, since the pulp is usually removed and what's left is largely water. Instead of drinking orange juice all the time, eat the whole orange, Lanza said.

A nugget from local dietitian Patricia Hausman's book, "Foods That Fight Cancer" (Rawson Associates, $16.95): Coarser wheat products like bran or shredded wheat are better sources of fiber than those such as whole-wheat bread. They also create more bulk in the digestive system and thus may be better protectors against colon cancer. The Bran Brigade

Bran Cereals: Ever since Kellogg's came out with its controversial advertising campaign supported by the National Cancer Institute, the players in the $615 million bran cereal market have been passionately one-upping each other in ad copy and box banners.

Sorting through all the hype, there are a few basic differences between bran cereals. All of them are made from the outer undigestible coating of the wheat kernel. The shredded variety, such as All Bran, is made by cooking the wheat bran, shredding it and then toasting it. Forty percent bran products (or bran products with fruit) contain part of the bran along with other parts of the wheat kernel. They are made by flaking the wheat kernels between high-pressure rollers. If there's more bran, there's more fiber.

Here's a quick fiber stack up: Topping the charts is Kellogg's Extra Fiber All Bran with 13 grams per ounce, then General Mill's Fiber One with 12 (both are sweetened with aspartame). Kellogg's All Bran and Nabisco's 100% Bran each has nine grams of fiber; Kellogg's Bran Buds has eight grams; Quaker Oat's Corn Bran, Ralston Purina's Bran Chex and Post's Bran Flakes have five grams each; General Mills' Bran Muffin Crisp, Kellogg's Bran Flakes, Kellogg's Cracklin' Oat Bran, Nabisco's Shredded Wheat 'n Bran, most raisin brans and the new Fruit 'n Fibre cereals from Post have four grams apiece; while General Mills' Total, Post's Grapenuts Flakes, General Mills' Wheaties and Cheerios, and Kellogg's Apple Raisin Crisp have two grams per serving.

Oat bran: This finely ground flour-like product, the new darling of the cereal set touted for its cholesterol-lowering abilities, is made from the outer portion, or bran, of the oat groat. In cooking, it just doesn't have the "termite appeal" as whole-wheat products sometimes do, said dietitian Hausman; it has a much more "delicate consistency."

Aside from oat bran being eaten as a hot cereal, it can be used as a partial flour replacement or filler in almost any kind of recipe. Dietitian Litt suggests just keeping a box on your stove as you would salt or pepper and throwing a tablespoon or two into soups and stews or sprinkling it onto cold cereals.

According to Nancy Nevin, supervisor of consumer communications at Quaker Oats, the company that sells an oat bran product under the Quaker and Mother's labels, oat bran can be substituted for 1/3 to 1/2 of the amount of flour called for in a recipe. Nevin cautioned against replacing flour entirely with oat bran because bran products do not contain the gluten or protein structure that flour does and thus the texture of the finished baked good may be affected.

And because oat bran is water-soluble, the resulting product will be gummy if you add too much of it, Nevin added.

Unfortunately, oat bran is not readily available in many parts of the country or in all markets, said Nevin, and the company recently discontinued publishing an oat bran recipe book.

Unprocessed wheat bran: Sold in supermarkets and health food stores as "unprocessed bran," "raw bran" or "toasted wheat bran," this product belongs to the family of insoluble fibers, the type credited with possibly preventing some forms of cancer.

Because it has different properties, it should not be used in the same quantities in recipes as oat bran, said Nevin. In addition, it has more taste and is coarser than oat bran. Wheat bran is more similiar to wheat germ than flour and will produce a less tender baked good than oat bran. Thus, it is more effective used in recipes as a topping, coating or to give a food textural crunch.

Quick Tips:

*Use shredded bran and bran morsel cereals interchangeably in recipes. When substituting bran flakes or raisin bran cereals for the shredded type of bran in recipes, use twice as much.

*A cup of flaked bran cereal will crush into approximately a 1/2 cup when processed in a food processor or blender. Use crushed bran flakes as a coating for chicken or fish. Add a few spices, such as sage or thyme and some grated parmesan to the crushed mixture.

*It helps to soak bran cereals in liquid for 1 to 3 minutes to soften before adding to recipes.

*To extend ground meats, add up to 1/2 cup shredded bran cereal for 1 pound of meat. Then add two tablespoons more liquid (tomato sauce or whatever) to the product. This type of cereal can also be used in place of nuts in recipes.

*When using oat bran as a thickening agent for soups, stews or sauces, allow 1 tablespoon for each 2 cups of liquid.

*Use oat bran in a "milkshake" or smoothie. Combine 1 cup skim milk, 3 tablespoons oat bran and 2 teaspoons cocoa powder or instant coffee powder. Add 1/2 teaspoon vanilla, if desired, and 2 ice cubes. Place in a blender, process and serve. Or, substitute orange juice for the milk and 1 ripe banana for cocoa or coffee. Process and serve. Oat bran can also be mixed into tomato-vegetable juices or fruit nectars.

*Use oat bran instead of heavy cream to thicken vegetable pure'es (you get double fiber on these). In the base of a blender or food processor, place 4 cups of sliced, cooked carrots, 3/4 cup of oat bran, 1/4 cup of skim milk, a tablespoon each of brown sugar and butter or margarine and nutmeg to taste. Process (in batches, if necessary), until smooth.

*Sprinkle unprocessed wheat bran onto dry cereals. A tablespoon or two of wheat bran can add a meaningful amount of fiber to a bowl of cereal, says local dietitian Mary Dickie.

Use any of the brans sprinkled into yogurt. Left-Out Legumes

"Beans have an image problem," said dietitian Janet Tenney of Giant Foods. Aside from the flatulence issue, many people have unfairly associated beans as a poor person's food, associating meat with affluence, Tenney said. But aside from being an excellent protein substitute for meat, legumes are also winners in the fiber field.

As for solving the flatulence problem, no research has been totally conclusive, according to Bonnie Liebman, director of nutrition at the Center for Science in the Public Interest. But there are some theories.

According to Liebman, Joseph Rackis of the USDA's Northern Regional Research Center in Peoria, Ill., came up with a procedure that he said reduced flatulence by up to 60 percent. Rackis' methods were based on soaking the beans for four or five hours, throwing out the liquid, then changing the liquid twice during cooking. Rackis also cooked his beans in a lot of water: nine cups to every cup of beans. This method presumably helped to wash out the undigestible sugars that cause flatulence.

The lengthy soaking and cooking time for dried beans may be a drawback, but there are several alternatives. For one, some dried beans require no soaking and less than an hour to prepare. That category includes black-eyed and split peas and lentils. A standard way to reduce soaking time, too, is to place the beans in boiling water and set aside for one hour before cooking. And some people don't soak their beans at all.

Another alternative is to use frozen or canned beans, although they are limited in selection. (Dr. James Anderson, a leader in fiber research at the University of Kentucky, said that not much fiber is lost in the canning process.) A possible drawback to canned beans is sodium; they contain anywhere from 300 to 450 milligrams of sodium per 1/2 cup. In this case, however, Liebman says that the benefits of eating a low-fat high-fiber bean dish probably outweigh the extra salt you may be consuming with a canned product. Most people salt their dried beans, anyway, Liebman said. But if you're watching your sodium intake carefully, you can always wash the beans, which should remove a sizable portion of the sodium.

Quick Tips:

*If you have the time, cook up a big pot of your favorite beans. Freeze them in portion-size containers and use in salads, sandwiches or over rice.

*Don't forget about chili or the myriad of Mexican foods with beans. Adams Morgan restaurants are a hotbed for bean dishes. Indian restaurants do wonders with lentils.

*To spiff up canned black beans for a quick side dish, cook them with chopped onions, green bell pepper, garlic and a bay leaf.

*To prepare lentils as a side dish, cook 1 cup lentils in 2 1/2 to 3 cups of tomato-vegetable juice. If serving them over rice, cook the same amount of lentils in 4 cups of juice. To make a soup, cook the same amount of lentils in 6 cups of the juice. Throw in a 1/2 cup of sliced carrots and a 1/2 cup of barley. Switching to Whole Wheat

Baking with whole-wheat flour: Hausman contends that most people don't like the flavor of 100-percent whole-wheat products, and that if all whole-wheat flour is substituted in a recipe that calls for white, the amount of fat will also have to be increased. Instead, Hausman suggested substituting half of the flour in a recipe for whole wheat.

Breads: Beware of "wheat" breads; white bread can be called "wheat bread." Make sure the ingredient label says "whole wheat." Also, whole-wheat bread is higher in fiber than other breads, but imported rye bread is also a good source. Lanza said that commercially-baked American rye breads are not made with a significant amount of whole rye flour.

Pasta: Whole-wheat pasta has four times as much fiber per serving as regular pasta, said Lanza. Heavier than regular spaghetti, this pasta takes some getting used to. It is readily available in health food stores.

Crackers: There are a lot of whole wheat crackers on the market, though some are also high in sodium and fat. Watch out if the ingredient label lists palm or coconut oil; they are saturated fats.

There are, however, a number of whole-wheat flat breads -- many of them imported from the Scandanavian countries -- which are both low in sodium and fat and loaded with whole-wheat fiber. Look for them in the specialty sections of the supermarket. Tenney of Giant Foods also suggested whole-wheat matzo.

Whole-grain hot cereals: The Center for Science in the Public Interest recently published a comparison of fiber contents in whole-grain hot cereals. Roman Meal, sold in the West, came out ahead, followed by Uhlman's Wheatena and Ralston Instant.

Quick Tips:

*Experiment with using part whole-wheat flour in recipes such as pizza doughs or pie crusts.

*Ease into whole-wheat pasta by mixing it with an equal quantity of the regular variety.

*Add extra fiber and flavor to hot cereals by topping them with chopped dried fruits such as prunes or raisins. You can also top them with a tablespoon or two of dried bran to add fiber and crunch. Fruits and Vegetables

Fruits and vegetables are probably the easiest high-fiber food to slip into your diet. Grabbing an apple or having a baked potato with dinner is already an American habit.

As for surprise high-fiber fruits, blackberries are good sources of fiber. And as for vegetables, peas and parsnips are high on the list.

Quick Tips:

*Eat foods closest to their original state. For instance, raw carrots are coarser and less easily digested than cooked, thus increasing intestinal mobility, said Lanza.

*When possible, eat fruits and vegetables with the skins on. Lanza said that fruit with the skins on can have anywhere from a half to a whole gram more fiber than their peeled counterparts.

*Strawberries, apples and blueberries are good sources of fiber for the amount of calories they contain, said Lanza. Prunes have more fiber and are not as high in calories as raisins. Keep these dried fruits in mind (along with dried apricots and figs) for snacks. Although high in calories, they are certainly better than eating a candy bar.

*Keep cut-up raw vegetables in a plastic bag in the refrigerator. That way, when you want a quick snack, it'll be there. Fiber-Rich Recipes

These varied recipes take fiber one step further: SHIRLEY CORRIHER'S FRUIT AND SPICE OAT BRAN MUFFINS (Makes 12)

1 1/2 cups oat bran

1/2 cup all-purpose flour

2 teaspoons baking powder

1/2 teaspon salt

1/2 teaspoon allspice

1/4 teaspoon cinnamon

3/4 cup brown sugar

Zest of 1 orange

1 egg

1/2 cup milk, preferably lowfat or skim

2 tablespoons vegetable oil

1/2 teaspoon vanilla

2 small apples or 1 pear and 1 apple, chopped

Combine oat bran, flour, baking powder, spices, brown sugar and grated orange rind. In a separate bowl, combine egg, milk, oil and vanilla. Combine the dry and the liquid ingredients with a few swift strokes. Fold in the fruit before the dry ingredients are entirely moist. Place in greased muffin tins and immediately bake in a 450-degree oven for 20 minutes. FIBER-PACKED APPLE CRISP (6 servings)

This recipe comes from the newsletter "Diabetes and Nutrition News," published by the HCF Diabetes Foundation, of which Dr. James Anderson is president.

1/2 cup uncooked oat bran

Margarine for greasing pan

5 cups thinly sliced apples

1 cup unsweetened apple juice

1/2 cup finely chopped prunes

1/2 cup raisins

Cinammon to taste

1/4 teaspoon cloves

1/3 cup bran flakes, crushed

Layer oat bran in the bottom of a greased 8-inch square pan. Place apple slices on top. Pour apple juice over and sprinkle with prunes, raisins, cinammon and cloves. Cover with foil and bake at 350 degrees for 1 hour. Remove foil, sprinkle with bran flakes and bake 15 minutes longer. MARY DICKEY'S WHEAT BRAN PANCAKES (Makes about 15)

1 cup unprocessed wheat bran

1 cup skim milk

1 tablespoon oil or butter

1 to 2 tablespoons brown sugar

1/2 cup white flour

1 tablespoon baking powder

1/2 teaspoon salt

1/8 teaspoon cinammon

1 egg, beaten

1 ripe banana, mashed

3/4 cup frozen blueberries, thawed

1/4 cup chopped pecans (optional)

Yogurt and chopped fruit, a drizzle of maple syrup, apple butter, applesauce or peanut butter for topping

Place wheat bran, skim milk and oil or butter in a saucepan. Cook mixture until hot (to soften bran). Set aside to cool.

In a mixing bowl, stir together brown sugar, white flour, baking powder, salt and cinammon.

When bran mixture is cool, add egg. Stir in mashed banana, blueberries and optional pecans. Add dry ingredients to bran and fruit mixture and stir just until combined. (This makes a thick batter.) Pour with a ladle onto hot griddle. Cook until pancakes bubble, then flip and cook on other side until done. Serve with topping of choice. TEXAS CAVIAR (8 servings)

Like other regional specialties that have suddenly gone chic, Texas Caviar is starting to crop up in New American cuisine restaurants and fancy food carryouts. As the story goes, the dish was originally invented by Helen Corbett, a cookbook author and director of restaurants at Dallas' Neiman-Marcus in the 1950s. Corbett, a native New Yorker, didn't care for the good luck legume as is, and so she pickled it. In Texas, the dish is served as a side dish with barbecue or at picnics. High in fiber, Texas Caviar is quick and easy to prepare.

4 cups cooked black-eyed peas*

1/2 cup olive oil

5 tablespoons red wine vinegar

2 jalapeno peppers, diced, or to taste

3 cloves garlic, minced

1/2 cup chopped red onion

1/2 cup each diced green and red bell peppers

Salt and freshly ground black pepper

Mix black-eyed peas in a bowl with remaining ingredients. Chill overnight, adjust to taste and serve.

*Frozen, canned or dried black-eyed peas can be used in this recipe. EIGHTEEN BEAN SOUP (10 to 12 servings)

This recipe is fun as a group project that the whole neighborhood, office, school or extended family can prepare. Chock full of fiber, it will familiarize you with the myriad of legumes available. Ask 18 people to contribute a pound of beans each. (Actually, any number of people can participate; six people can bring three pounds each, three people could bring six different beans, and so on.) The object is to get the beans all in one place, mix them all up and redivide the now-colorful mixture back into 18 one-pound packages. It is a fairly lengthy preparation, but it makes a lot of soup and can be frozen.

1 pound each of dried pigeon, small white California, pink, red chili, garbanzo, roman, pinto, black, navy, lima, great northern, kidney and october beans, yellow split, black-eyed and green split peas, lentils, barley*

FOR THE SOUP:

1 pound of 18-bean mixture

Leftover ham or hamhock (optional)

1 large onion, cut lengthwise

29-ounce can tomatoes, undrained

1 clove garlic, minced

Juice of 1 lemon

Salt, black pepper and red pepper flakes to taste

Place 18 pounds of beans in a large pot or basket. Mix until well combined. Redivide mixture into 18 one-pound packages. (You can divide them into larger portions, too, just adapt the recipe accordingly.)

To make the soup, wash beans. Place in a pot or bowl and cover with cold water. Soak overnight.

Drain water from beans and place them in a large saucepan or stockpot. Add 2 quarts fresh water. Add optional ham or hamhock and onion. Bring to a boil and simmer, covered, 2 1/2 to 3 hours.

Add tomatoes, garlic, lemon juice and salt and black and red pepper flakes. Simmer until beans are done, about 30 minutes.

*All the beans should be available at local supermarkets (Magruder's stocks a large variety of beans) or specialty shops such as Hispanic, Indian or Caribbean markets. If you cannot find all of them at your local market, use two pounds of another kind of bean. CURRIED PEAS AND LENTIL RICE (4 servings)

This easy dish combines peas and lentils, both good sources of fiber.

1/2 cup diced green bell pepper

1/2 cup chopped onion

2 large cloves garlic, minced

1 tablespoon oil

1 cup lentils, rinsed and drained

1 cup brown rice, uncooked

1 teaspoon curry powder or more to taste

5 cups chicken broth, tomato juice or water

10-ounce package frozen peas, cooked

Combine pepper, onion, garlic in saucepan with oil. Cook until soft. Stir in lentils, rice and curry, add broth and simmer until tender, about 40 minutes. About 5 minutes before the dish is finished, stir in cooked peas. MEXICAN LASAGNA (6 servings)

FOR THE ENCHILADA SAUCE (or substitute 1 1/4 cups canned enchilada sauce):

2 cloves garlic, minced

1 small onion, chopped

2 teaspoons oil

1 teaspoon oregano

1/2 teaspoon cumin

1/2 teaspoon chili powder

1 cup tomato sauce

FOR THE LASAGNA:

1 medium onion, chopped

1 tablespoon oil

16-ounce can tomatoes

2 15-ounce cans kidney or pinto beans, drained

2 teaspoons chili powder or more to taste

1 teaspoon cumin or more to taste

1 cup part-skim ricotta cheese

3/4 cup grated monterey jack cheese

4-ounce can chopped mild green chilies

3 tablespoons chopped minced coriander (optional)

9 corn tortillas

To make enchilada sauce, saute' the garlic and onion in the oil. Add remaining ingredients and simmer over low heat as you prepare the lasagna.

To make lasagna, saute' onion and oil in a saucepan until tender. Drain tomatoes, reserving 1/4 cup liquid. Chop tomatoes roughly. Stir tomatoes and reserved liquid, beans, 1/4 cup enchilada sauce, chili powder and cumin into the onion. Set aside. Mix ricotta cheese with 1/2 cup of the monterey jack, chilies and coriander.

Pour 1/3 of the enchilada sauce in the bottom of an 9-inch square pan. Place 1 whole tortilla in the middle and quarter 2 others, placing them in the corners and along the sides. Place half of bean mixture on top of tortillas, then 3 more tortillas (1 whole, 2 quartered), another 1/3 of the enchilada sauce, all of ricotta cheese mixture, the remaining 3 tortillas, the remaining enchilada sauce and the rest of the bean mixture. Sprinkle with remaining monterey jack. Cook for 30 minutes at 375 degrees and serve.