Nutritionists agree Americans don't get nearly enough fiber. And many consumers know that for some reason they need more of the stuff. But foods traditionally high in fiber -- oat bran, wheat bran, dried beans -- aren't usually A-list menu items in most households.

Enter the nation's packaged food makers, led by Golden Valley-based General Mills. In recent years, it has figured out ways to boost fiber levels in scores of foods -- from yogurt to soup to toaster pastries -- without marring taste or texture.

The fiber fix has been a commercial hit. General Mills' "Fiber One" brand is one of the company's fastest growing properties; its Fiber One breakfast bar alone has risen to the top of the snack bar heap in just three years.

But does all this new fangled-fiber have the same physiological benefits as traditional sources of fiber? "That's the question of the century in terms of dietary fiber," said Joanne Lupton, a food science professor and fiber expert at Texas A & M University.

The answer isn't clear, Lupton and other food scientists say. The new crop of fiber-enhanced foods has beneficial health effects, but not necessarily of the magnitude associated with fiber found in traditional such sources as legumes, oat bran and wheat bran, nutrition experts say.

"It's sort of been a giant loophole," said Bonnie Liebman, nutrition director for the Center for Science in the Public Interest, a labeling watchdog group. "My concern is that most people assume that all fibers are equal," she said. "But the evidence just isn't there."

Susan Crockett, General Mills' senior technology officer for health and nutrition, said the company's fiber-fortified offerings are delivering for consumers, helping them fill their fiber gaps. "We can do it in a way that food actually tastes good so people will actually eat it," she said. "This is a huge positive for the American diet. We are meeting needs that are far from being met."

Fiber, the parts of plants that your body can't digest, occurs naturally in a host of foods, from whole grains and fruits and vegetables to lentils and nuts. Some fibers -- notably those found in oats, barley and legumes -- can help lower cholesterol levels and reduce the risk of diabetic problems. And generally, consuming a lot of traditional dietary fibers is associated with lower risk for heart disease, obesity and gastrointestinal diseases.

Yet for all those benefits, Americans generally consume less than half the fiber recommended by federal health guidelines. For most, taste comes before nutrition, and a healthful serving of wheat bran does little to whet the appetite.

Roots of the chicory herb

In theory, foodmakers could fortify their offerings with traditional sources of fiber. But consumers would blanch at the ensuing gummy or cardboard consistency, or the brownish tint they'd lend. Foodmakers have gotten around the problem by turning to natural fibers that impart no color and aren't so viscous or gritty -- and then transplanting them.

Take inulin, a popular new-breed fiber, which counts Minnetonka-based Cargill Inc. as one of its major manufacturers. Inulin is extracted from the roots of the chicory herb and added to a host of products. "It's the food manufacturer's dream," said Julie Jones, a nutrition professor at St. Catherine University in St. Paul. "It has the least impact on taste and texture."

Foodmakers, armed with better fiber technology, have swung into action with a host of new products aimed at mating health with taste.

New U.S. food and beverages launched in 2009 with an explicit fiber claim represented 5.5 percent of all new food and beverage products, more than double 2006's level, according to market researcher Mintel International.

Kellogg offers a high-fiber rendition of its venerable Pop-Tarts -- "20 percent daily value fiber," the package shouts. Campbell Soup markets a high-fiber take on its V8 juice. Even one version of Splenda, the well-known packet sweetener, is fiber-fortified.

But General Mills is out front. It has added fiber to its Yoplait yogurt line via "Yoplus" and recently launched a high-fiber version of its Progresso soups. Then there's the Fiber One brand.

"I would consider [General Mills] to be a real trailblazer in the market," Mintel analyst Krista Faron said. "What they have been able to do is make fiber mainstream and accessible. Fiber One has mastered the balance between taste and nutrition."

Some breakfast cereals have long been decent sources of fiber, and Fiber One started out as a lone cereal offering in 1985. "It sat quietly on the shelves until 2002," said David Clark, General Mills' vice president of marketing for adult cereals.

By then the Atkins Diet had taken off, and fiber got a good shake in that eating regimen, Clark said. A second Fiber One cereal -- Honey Clusters -- was added in 2005, and three more iterations have been launched since.

The Fiber One lineup now includes yogurt, toaster pastries and pancake and muffin mixes, and together the brand generates more than $300 million in annual sales. Its biggest success: Fiber One breakfast bars the company launched in 2007. "That was a tremendous breakthrough," Clark said. Indeed, for the 52 weeks through April 18, Fiber One was running neck and neck with Kellogg's Special K bar as leader of the U.S. breakfast/cereal/snack bar category, according to SymphonyIRI Group, a market researcher. Each bar had about an 18 percent market share.

One Fiber One bar boasts 35 percent of the daily recommended amount of fiber. A look at the package shows that the bars' lead ingredient is chicory root extract -- i.e. inulin, which is also the main fiber-fortifier in Fiber One yogurt and pancake and muffin mixes. Inulin is added to some versions of Fiber One cereal, though its primary fiber sources are whole grain wheat and corn bran.

Inulin's benefits "are well established with scientific agreement," said General Mills' Crockett.

Inulin clearly has properties that are good for gut health, nutritionists say. "It's a very good prebiotic," said Texas A & M's Lupton. Prebiotics are fibers that stimulate the growth of good bacteria in the colon and inhibit the growth of unhealthy bacteria. Research hasn't yet shown whether that translates into a decreased likelihood of disease, Lupton said.

So far, there's scant evidence that inulin can help lower cholesterol or glucose levels akin to fibers like oat bran or legumes, several nutritionists said. And while inulin has positive effects on regularity, nutritionists say those effects aren't as pronounced as they are with wheat bran, the gold standard for laxation.

Despite any limitations of inulin and other new fiber-fortifiers, several nutritionists said consumers are better off with them than without. Americans fall so short of recommended fiber goals, every bit of extra fiber helps.

"We should try every mechanism possible to increase dietary fiber," Jones said. "We should encourage manufacturers to add fiber in tasty ways so people will eat it."

Still, many nutritionists recommend that consumers get the bulk of their fiber from traditional sources. "I'd prefer we don't over-supplement," said Joanne Slavin, a food science professor and fiber expert at the University of Minnesota. "I don't want people to eat three [fiber-fortified] bars a day and say, 'I'm good to go.'"

That's because Slavin and other nutritionists say foods long associated with dietary fiber -- from whole grains to fruits and vegetables -- are integral to a healthful diet. Traditional high-fiber foods are often full of vitamins, tend to be low in fat, and they're filling, which helps keep people from overeating.

"They're very good foods for you, high-fiber foods," said Texas A & M's Lupton. "They're going to automatically give you a good diet."

Mike Hughlett • 612-673-7003