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All sources of fiber are not created equal

Tuesday, August 10, 2010

Gone are the days of getting your fiber from only bran flakes and prunes. Now manufacturers are adding fiber to yogurt, ice cream, snack bars, muffin mixes, water and juice. But are all fibers equal? Experts recommend that consumers consider more than the amount of fiber listed on the Nutrition Facts panel and the words printed on the box.

Adequate fiber in the diet is needed to lower the risks of certain chronic diseases. The current recommendation, according to the 2005 Dietary Guidelines for Americans, is 14 grams of fiber per 1000 calories. Women younger than age 50 should aim for 25 grams of fiber and men need 38 grams a day. The amount of fiber needed for people over 50 decreases because calorie needs decrease with age. Women over 50 need 21 grams and men need 30 grams. What is needed and what the average American gets seldom match, as most Americans consume about half the recommended levels.

Joanne Lupton, nutrition professor at Texas A&M, specializes in dietary fiber and colon cancer. She reports that there is a very long history of high fiber foods -- whole grains, fruits, vegetables and legumes -- being protective against a variety of diseases including heart disease and diabetes. Other researchers question if it's the fiber or something else in whole grains, such as phytoestrogens, antioxidants, lignans, vitamins or minerals, that is protective.

Dietary fiber is known as roughage, or bulk, and includes all parts of plant food that the body can't digest or absorb. It is commonly classified into two categories -- insoluble and soluble.

Insoluble fiber does not dissolve in water and promotes the movement of material through the digestive system and increases stool bulk. Whole wheat flour, wheat bran, nuts and many vegetables are good sources.

Soluble fiber dissolves in water to form a gel-like material. It can help lower blood cholesterol and glucose levels and is found in oats, peas, beans, apples, citrus fruits, carrots, barley and psyllium. Many fruits, vegetables, beans and nuts have a mix of soluble and insoluble fiber.

The fiber being added to many foods today is functional fiber. It is a non-digestible carbohydrate that can be extracted or isolated chemically. Like soluble fiber, functional fibers are often soluble in water but they are not always "sticky" so they can't lower cholesterol levels the way that soluble fiber can.

The American Dietetic Association maintains that fiber found in natural foods is superior to added or functional fiber. More studies must be done to fully determine the difference. Natural and added fiber will look the same on the Nutrition Facts panel, which tells the total grams of dietary fiber in a serving of packaged food. To find out whether that fiber is natural or added, look at the ingredients list located on the packaging. The most common added fibers used are maltodextrin, inulin, polydextrose, oat fiber, resistant starch, pectin and gum.

Eating five fiber-fortified yogurts a day might meet a person's fiber goal. But it's not the same as getting 25 grams of fiber from a variety of fruits, vegetables and whole grains.

Fiber-fortified foods and snacks may lack the healthy chemicals found in plant foods. It's important to think about the food as well as its fiber content. Fiber put into a food that is high in calories, fat or sodium, may be a poor choice and a waste of calories.

Eating foods with added fiber won't hurt you, but eating naturally fiber-rich foods is recommended because they contain a mix of different fibers as well as important vitamins, minerals and phytochemicals. Variety and moderation count in all things.

Editor's Note: Ann Ludlum is a K-State Research and Extension family and consumer sciences and 4-H extension agent assigned to Bourbon County. She may be reached at (620) 223-3720 or aludlum@ksu.edu.

Ann Ludlum
FCS Agent, Southwind District
Editor's Note: Ann Ludlum is a K-State Research and Extension family and consumer sciences and 4-H extension agent assigned to Southwind District -- Fort Scott office. She may be reached at (620) 223-3720 or aludlum@ksu.edu.