Yogurts with added fiber actually contain inulin, a group of simple sugars that are not digested. Inulin occurs naturally in chicory root and other plants and grains and is a form of soluble fiber but, like resistant starches, doesn't have the same anticholesterol effects, says Slavin. It, too, has prebiotic effects.
So what's the bottom line? The federal government's just-released Dietary Guidelines for Americans call for about 25 grams of daily fiber for women and 38 for men, and research shows we are getting only about 15 grams. But because the health benefits of different types of fiber vary—and in many cases are not clear or consistent—the best advice is to eat an array of plant-based foods, including fruits, vegetables, legumes, and whole grains. That's despite the new findings that only fiber from gains is linked to a lower risk of early death. Worry less about targeting specific types of fiber and "get [it] from as many different foods as you can," advises Slavin. And if you are selecting packaged foods on the basis of their fiber content, be sure that they are healthful in and of themselves. Cracklin' Oat Bran, for example, has 6 grams of fiber per serving, but 30 percent of its calories come from sugar and it has 3 grams of saturated fat.
This article was originally published on 5/5/2009. It has been updated.