Fiber can be classified as functional fiber, dietary fiber, and total fiber and all share the property of not being broken down by human digestive enzymes. Dietary fiber like whole grains has many health benefits, like regulating blood glucose and decreasing blood cholesterol. It also helps to create a feeling of fullness to aid in weight loss. Dietary fiber comes in two forms — one form dissolves in water, the other doesn’t — and both are found in fruits, vegetables, legumes, nuts and grains. “But these are foods that Americans just don’t eat enough of anymore”, says Mian Riaz, director of the Food Protein Research and Development Center at Texas A&M University in College Station. Women and men younger than 50 need a total of about 25 grams or 38 grams, respectively of fiber per day. People older than 50 need a few grams less. But on average, American women get about 13 grams and men 17 grams, according to a 2005 report by the Food and Nutrition Board of the Institute of Medicine.
Leave it to the food companies to come up with a solution with the functional fibers, those added to foods by the manufacturer. Every food producer seems to want to put some kind of fiber into their product these days, but there are some concerns and questions about whether some of the fibers added to foods have the same health effects on the body, as does dietary fiber.
A growing number of products, like Yoplait’s Fiber One yogurt, are getting some or all of their fiber added with ingredients called inulin, maltodextrin and polydextrose. Manufacturers add these to boost their product’s fiber content. Inulin is commonly extracted from chicory root, so look for chicory root extract on the ingredient label. Maltodextrin, are long chains of glucose strung together.
Polydextrose is synthesized from glucose and sorbitol. These fibers are showing up products like yogurt or ice cream that never had any fiber in the first place. These fiber additives serve dual purposes—they can serve as bulking agents to make reduced-calorie products taste better, such as the case with Breyers fat-free ice cream, and carry an added appeal to consumers by showing up as dietary fiber on food labels. “They’re considered fiber because, like naturally occurring fiber, they’re resistant to digestion”, says Mary Ann Johnson, professor of foods and nutrition at the University of Georgia in Athens and a spokeswoman for the American Society for Nutrition. “However, these functional fibers lack the array of vitamins, nutrients, antioxidants and plant chemicals found in whole grains, fruits and vegetables”, says Jennifer Anderson, professor of food science and human nutrition at Colorado State University in Fort Collin
“We just don’t know if they all act the same,” says Jennifer Nelson, director of clinical dietetics and nutrition at the Mayo Clinic in Rochester, Minn. “They have not necessarily been studied to see if they’re beneficial.”
According to Food and Drug Administration guidelines, a food can be labeled a “good” source of fiber if a serving contains at least 2.5 grams of fiber and “high” in fiber if a serving contains at least 5 grams
“Don’t just look at the number [of fiber grams] or the health claims,” Nelson says. “Dig down into the ingredients.” Better yet, says Johnson, get as much dietary fiber as possible from whole foods.
There are some gastrointestinal drawbacks with the intake of some of these functional, added fibers. See my previous post, entitled “Maybe It is Something You ate – Fructans”.