If It’s High in Fiber, It’s Rich in Benefits

Like many pieces of the dietary advice jigsaw puzzle, fiber continues to be a confusing issue.

This non-nutrient nutrient (so designated because it is indigestible and therefore has no calories) has had its research up and downs. It has gone from being basically unknown to being the best thing since sliced bread (pun intended) to being of questionable value.

Like it or not, that’s the way science works. Research results get added to other research results, and then all of a sudden some new research comes along and changes the original research results. But often, if you wait awhile, the original results may be back in fashion. This is pretty much what has happened to fiber.

We have always promoted the idea that diets high in fruits, vegetables, legumes and whole grains seem to be protective against colon cancer and heart disease, useful for keeping blood sugar in check and helpful in weight loss. However, in January, a really good research study carried out on more than 88,000 nurses showed that a high-fiber diet seemed to offer no protection against colon cancer.

Of course, the media just ate this up (pun intended again).

Even if these results stand up to future scrutiny, and it turns out to be something else in foods that protects against colon cancer (because something clearly does), the benefits of fiber are still enormous.

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For many years, oat bran was being touted as the shining star of the fiber family, but there are at least six types of dietary fiber, divided into two distinct categories, soluble and insoluble. Oat bran falls into the soluble group, which also includes barley, rice bran and fruit.

The job of soluble fiber is to absorb water in the intestinal tract and slow down the time needed to empty the intestine. Eating these fibers makes you feel full and may help in weight loss. These are also the fibers credited with helping to lower “bad” cholesterol levels in the blood. Nobody knows exactly why this works, but in the presence of an otherwise low-fat diet, the addition of soluble fiber (including, but not limited to, oat bran) seems to have this effect.

Insoluble fibers also draw water into the intestinal tract, but rather than slowing down digestion, they speed it up and increase the amount and frequency of bowel movements. These fibers include wheat bran, whole grains and vegetables and are credited with helping to protect against certain types of cancers, especially of the colon.

To achieve the maximum benefit from eating fiber, try to get both types into your diet. Plant foods all contain both types of fiber--although some are particularly rich in one or the other.

Which foods have which type of fiber? The following lists show which foods fall into each category.

Insoluble fiber:

* Wheat bran

* Apple and pear skins

* Peas and carrots, other vegetables

* Bran cereals

* Whole-grain breads (toasted or not)

* Pears

* Browned potatoes

Soluble fiber:

* Dried beans and peas

* Lentils

* Oats

* Barley

* Psyllium laxatives

* Sesame seed

* Fruit, especially bananas, apple pulp, citrus, grapes, apricots, cherries

* Vegetables, especially potatoes, cabbage, carrots.

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Is it true that too much fiber is worse than too little? There can definitely be some drawbacks to getting too much fiber, particularly in terms of mineral absorption, but the likelihood of becoming depleted of certain minerals because of the amount of fiber in the diet is probably not a real concern. However, many people who begin consuming a high-fiber diet do experience cramping, intestinal gas and bloating. Most of these problems can be avoided by adding fiber to the diet slowly.

In fact, if you are starting now to consciously increase fiber in your diet, spread the increase out over a month or so to give the intestinal tract time to get used to it. It is also important to drink plenty of fluids to avoid constipation, particularly from the insoluble fibers.

How much fiber does a person need and how can he or she get it? There is no recommended daily allowance for fiber, and the advice varies, but somewhere from 20 to 35 grams of fiber a day (a combination of soluble and insoluble) is probably about right. Since about 50% of your calories should come from complex carbohydrates, which are good sources of fiber, this shouldn’t be hard to do.

It is often difficult to tell how much fiber you’re getting in a particular food because there are two ways to measure it. Crude fiber measures the amount of fiber left after the food is treated with acid and alkaline solutions. Anything not digested in this process is called “crude fiber.”

There are now newer methods that use weaker chemicals and enzymes that tend to isolate the fiber and preserve it rather than destroy it. These newer techniques result in measurements called “dietary fiber,” and in the same food they can be two to five times greater than the amount of “crude fiber.” The dietary fiber content of any food with a nutrition label is listed under carbohydrates.

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The following hints may help you increase the dietary fiber you eat.

* When you have a choice, eat whole grains. For example, substitute whole wheat for wheat bread, pumpernickel for a croissant, brown rice for white rice and whole wheat pastas for enriched pasta.

* Try eating fresh fruits and vegetables (with skins when possible) instead of just relying on fruit and vegetable juices. Dried fruits are also a good source of concentrated fiber.

* Be sure you don’t end up adding fat to your diet while you are trying to increase fiber. For example, popcorn has more fiber than chips, but if you add butter you are no better off.

* Try to use legume-based dishes instead of meats as often as possible.

* Bean soups and dips for vegetables are great meal starters.