Fill'er Up...With Fiber

Does the phrase "dietary fiber" make you think of wood pulp, bran cereal, and celery strings? Fiber-rich foods can be way more appetizing than that: creamy oatmeal, crunchy popcorn, fresh fruit salad. High-fiber foods not only taste good, they're also major contributors to good health and disease prevention.

What is Fiber?

Fiber is the component of cell walls that gives plants their shape and stiffness. Even though fiber is a type of carbohydrate, our bodies cannot fully digest it, so it provides no calories. Cows have digestive enzymes that can break down fiber, which is why they can survive on grass.

Two Kinds of Fiber

There are two main types of fiber: soluble and insoluble. Most plant foods contain both kinds in varied amounts. Since both types are indigestible, they are not absorbed into the bloodstream, but stay in the digestive tract to be excreted. Even though fiber cannot be used for energy or nutrition, both types have unique functions.

Soluble fiber dissolves in water and becomes gel-like during digestion. It promotes proper absorption of nutrients by slowing digestion in the stomach and intestines. Foods that contain soluble fiber include fruits, oats, barley, dried beans and peas, nuts, seeds and some vegetables. Soluble fibers like pectin, mucilage, or gum are added to some foods during manufacturing.  

Insoluble fiber, often called roughage, does not dissolve in water. It provides bulk to help move foods through the intestines. Insoluble fiber is found in whole wheat products, fruit and vegetable skins, corn bran, seeds, and nuts.

Health Benefits of Fiber

Fiber is good for digestion and bowel health and is often used to treat constipation and irritable bowel syndrome. Some food fibers function as natural prebiotics in the colon, encouraging the growth of good bacteria. Fiber helps prevent colon cancer by moving toxins through quickly and by promoting a healthy intestinal pH level. 

Another benefit of fiber is its role in reducing the risk of chronic diseases such as heart disease, diabetes, and obesity. Soluble fiber works against heart disease by binding with fatty acids in the intestines and lowering blood cholesterol levels. It also plays a role in regulating blood sugar. Fiber-rich foods can help with weight loss because they are usually lower in fat and calories, plus the added bulk helps us feel full longer.

How Much Fiber do I Need?

The recommended intake for dietary fiber is 21-25 grams per day for women and 30-38 grams per day for men. According to the American Dietetic Association, most Americans get only about half the recommended amount.

The nutrition label provides the total grams of fiber in a serving of food. Don't worry about whether you're eating soluble or insoluble fiber. Just try to consume more plant foods and you will boost both kinds.

When increasing your fiber intake, be sure to drink plenty of liquids. Add more fiber to your diet gradually so your digestive system gets used to it without side effects like gas and bloating.

What About Whole Grains?

The 2005 Dietary Guidelines for Americans define a whole grain as a food made from the entire grain seed, which consists of the bran, germ, and endosperm. The word "wheat" or "multigrain" on the label does not always mean whole grain. To get real whole grains, look for "100% whole wheat," "whole oats" or other whole grains as the first or second ingredient.

The labeling has become more complicated with the advent of "whole grain health claims" found on the front of food packages. An "excellent" source of whole grains contains 16 grams of whole grain per serving. A "good" source contains 8 grams of whole grain per serving.

But here's the tricky part: grams of whole grains are NOT the same as grams of fiber. Your best bet for comparing the fiber content of food products is to look at the grams of fiber on the nutrition panel. A "high-fiber" food contains 5 grams of fiber (or more) per serving. A "good" source of fiber contains 2.5-4.9 grams of fiber per serving.

Tips for Getting Enough Fiber

1) Eat several high-fiber foods at every meal.
2) Snack on veggies, fruit, nuts, or popcorn.
3) Use whole grain breads, whole wheat pastas, and brown rice instead white.
4) Eat beans a few times each week.
5) Aim for at least 2 cups of fruit and 2-1/2 cups of veggies each day.
6) Add oat bran, oatmeal, or wheat bran to muffins, bread, meatloaf, casseroles, or sauces.

To recap, if you want to increase your fiber intake, a good way to start is to check the grams of fiber per serving on the nutrition panel. Substitute whole grains for their white counterparts and eat more fruits, veggies, nuts, seeds, and beans. To get the maximum health benefits from different antioxidants, eat a variety of high-fiber foods each day. That's fiber in a nutshell!

SOURCES:

"Dietary Fiber: An Important Link in the Fight Against Heart Disease." American Dietetic Association nutrition factsheet, 2006.

Shanta-Retelny, Victoria, RD. "The Whole Story – Fiber, Whole Grains & Health." Today's Dietitian, February 2005.

Tsang, Gloria, RD. "Fiber 101: Soluble Fiber vs. Insoluble Fiber." November 2005. HealthCastle.com Web site. www.healthcastle.com/fiber-solubleinsoluble.shtml Accessed 12/20/08.

U.S. Department of Health and Human Services and the U.S. Department of Agriculture, Dietary Guidelines for Americans, 2005. Available at www.healthierus.gov/dietaryguidelines/index.html Accessed 1/3/09.