Food manufacturers, who are aware of both the health benefits of fiber and the public’s reluctance to eat naturally high-fiber foods, have attempted to appeal to health-conscious consumers by adding isolated fibers (sometimes called “functional” fibers) to a variety of foods such as cereals, soy milk, dairy products, crackers, and juice. These fibers are called “isolated” because they are extracted from starchy foods or synthesized from a variety of starches and sugars. The added fibers are commonly in the form of soy, psyllium, cellulose, guar, inulin, polydextrose, oat beta-glucan, fructooligosaccharides, and digestion-resistant maltodextrin.
“Many snack bars and yogurts use inulin and oligofructose as the fiber component,” says American Dietetic Association (ADA) spokesperson and dietitian Marisa Moore. “These forms of fibers are not digested and may improve absorption of calcium and magnesium.”
But do these added fibers have the other benefits associated with naturally occurring dietary fiber?
“Most of the research has been done on intact fiber, fiber in fruits, vegetables, and whole-grain products, and not isolated fibers, which has been added to foods. Long-term studies need to be conducted on the effects of intact versus isolated fibers,” says dietitian and ADA spokesperson Toby Smithson.
Constance Brown-Riggs, also a dietitian and ADA spokesperson, adds, “Isolated fibers do not function the same as dietary fibers. While these isolated fibers are soluble, they are not viscous, they are not gummy. If these isolated fibers were gummy, then the foods they were added to would be gummy, and gummy ice cream would not sell.”
Health-care professionals do, however, agree that fiber-enhanced foods can be part of a healthy diet. “Fiber-enhanced foods can help people with diabetes control hunger, which can help with weight management and overall blood sugar control,” Moore says. These newly developed foods may help people make the transition from a lower-fiber diet to one that is higher in fiber and whole grains.
To see what effect these foods have on blood glucose, “I caution my clients to count grams of carbohydrate and monitor blood glucose before and two hours after eating to see how these foods affect their individual blood sugar,” Brown-Riggs says.
Refined whole grains
In addition to adding isolated fiber to foods, food manufacturers have been finding ways to make whole grains more palatable to consumers. Whole or minimally processed grains are usually good sources of fiber, and they have some other benefits, as well: They have more protein and more naturally occurring vitamins and minerals than refined grains that have had their bran layer and germ stripped away during milling. The current Food Guide Pyramid recommends making half your grain choices whole to take advantage of these benefits.
To retain the beneficial qualities of whole grains while satisfying the public taste for refined grains, ConAgra Mills has created Ultragrain, a milling process that grinds whole-grain flour so finely that it has the same particle size as traditional, refined white flour. According to ConAgra’s Web site, this milling process retains the fiber, protein, minerals, and phytonutrients, while creating a flour that has the taste, texture, and appearance of white flour. Ultragrain flour is currently used to make Wonder Whole Grain White bread and Pepperidge Farm Whole Grain Goldfish Crackers.
Agribusiness giant ADM has a product similar to Ultragrain called Kansas Diamond, a selected blend of hard white wheats that are also milled to an exceptionally fine granulation.
According to Brown-Riggs, the only difference between the new whole wheat white flours and traditional white flour is that the bran has been left in the new varieties. However, she says, “These are highly processed flours, and it is not clear if the fiber quality is maintained. Further research is needed.”