Since the early 1950's when the term was first coined, dietary fiber has been known as a type of carbohydrate from plant foods that is not digested or absorbed. They are talked about many times based on their two different types, soluble and insoluble. Soluble fiber touted for its blood cholesterol lowering benefits and ease to acquire from foods such as oats, beans, lentils, citrus fruits, and carrots. Insoluble fiber recommended for its benefits for the digestive system and healthy food sources such as bran, whole grain products, fruit, and vegetables.
Food manufacturers have begun adding fiber to foods that were previously fiber free. (Learn more about this "stealth fiber.") Foods such as yogurt, ice cream, or drinks with isolated fibers confuse the issue for many consumers. Since many of these isolated fibers can affect the gastrointestinal system and do not contain health protective benefits, it is important to know about new classifications of fiber and why these new additives are permitted.
In 2001, a Panel on the Definition of Dietary Fiber (an Institutes of Medicine panel) responded to an FDA request to formally define dietary fiber. The IOM referred to recommendations and work done by the AACC (American Association of Cereal Chemists) and developed definitions that were presented to the FDA. New definitions focus on diversity of non-digested carbohydrates in the food supply. They broaden the definition from just plants to include carbohydrates contributed by animal foods as well. They also open the door to manufactured fibers as well. So what does this mean to you when you are trying to monitor your fiber intake?
In the proposed new definitions, Dietary Fiber is "non-digestible carbohydrates as well as lignin that are intrinsic and intact in plants." Non-digestible material includes those from foods that are not digested or absorbed in the small intestine as well as chemically created fibers that aren't absorbed either. Functional fibers are "those that may be isolated or extracted non-digestible carbohydrates using chemical, enzymatic, or aqueous processes." Manufactured resistant starch and modified natural sources are also included. Animal-derived carbohydrates like connective tissues are also newly included since they meet the new technical definition of "non-digestible." Now, newly synthesized products are listed as fiber on food labels.
In the fall of 2007, the FDA issued an advance notice of proposed rulemaking for comment on the new definitions for fiber. There is currently one category of dietary fiber on the Nutrition Fact label. The total reflects the sum of the dietary fiber and functional fiber for total fiber. The terms soluble and insoluble will eventually be phased out once analytical methods and processes are established to distinguish natural from created fibers. Currently these analytical issues prevent one clear cut set of guidelines from being followed. It is important to remember that these new definitions originated with a cereal organization. As I touched on briefly last week, marketing can be a wonderful thing. It can also cause people to venture away from the truth in favor of false promises. Food labels include isolated fibers and resistant starches as well as dietary fiber and functional fiber divisions in per serving fiber counts. However, fiber from these sources may not aid health such as lowering blood cholesterol or reducing diabetes risks in the same way their whole food counter parts might.
The Bottom Line
Fiber is an important part of a healthy diet. Not only does it help with digestion and regularity, it also provides heart and diabetes health benefits as well. Be careful when you read labels and see dietary fiber and functional fiber information on processed foods. Marketing hype can cause you to believe you are meeting your fiber recommendations eating high-fiber ice cream or toaster pastries. Allow your inner Spark to shine through and remind you that the fiber in a processed food will never be better for you than that of the naturally occurring fiber from a whole food. Focus your fiber counting around oats, oat bran, whole grains, fresh fruits and vegetables and dried beans. This will allow you to be certain your health will be benefitted and you have limited your processed foods including processed fiber.
Did you know there were new definitions for fiber? Did you notice changes for fiber reporting on nutrition labels? What are your favorite fiber sources?
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