Is Adding Fiber To Food Really Good For Your Health? : The Salt Fiber-fortified products are all over the supermarket. But are these foods actually making you healthier? This question turns out to be one of those places where scientists know a lot less than you may think they do.

Is Adding Fiber To Food Really Good For Your Health?

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It's MORNING EDITION, from NPR News. Good morning. I'm Steve Inskeep. Today in "Your Health," we plunge into energy drinks - after we take a look at fiber, which is in almost every aisle of the grocery store. Food manufacturers are putting fiber into foods where you would not expect to find it, hoping to make their products look more healthful - which raises the question, are they actually more healthful? Amy Standen, of member station KQED, went to find out.

AMY STANDEN, BYLINE: I'm standing here at the grocery store, and I'm facing this wall of really sugary kid cereals. And a lot of them have this label on it; it says, good source of fiber - which, if you think about it, may say more about us, the shoppers, than it does about what's in this box.

JOHN SWARTZBERG: We're looking for elements within things - almost a mystical kind of thinking.

STANDEN: John Swartzberg is a professor of public health at the University of California-Berkeley. And he believes that mankind's love affair with food additives - for example, fiber - can be traced back to a single moment in history: British Navy, 1747.

SWARTZBERG: Well, they realized that when the sailors were eating citrus fruits, they didn't get this terrible disease called scurvy.

STANDEN: You may have heard this story. A Scottish surgeon named James Lind started giving sailors limes, found that scurvy virtually disappeared.

SWARTZBERG: That's what got the English sailors got the name limeys.

STANDEN: This launched the idea that specific, isolated ingredients in foods could prevent, sometimes even cure, diseases. And often, they could.

SWARTZBERG: These things led us to think that well, we just have to find these magic bullets within foods that we replace, and we'll be much better.

STANDEN: And the legacy of this, says Swartzberg, is on full display at any modern grocery store.

JAN MATSUNO: Well, we can start with like, breakfast cereal.

STANDEN: With me shopping was Jan Matsuno. She's a food scientist for the Center for Culinary Development, a research firm in San Francisco. Matsuno has watched the trends come and go: the low carbs, the Omega-3s. She says what's enabled the fiber craze is, in part, chemistry.

MATSUNO: It's very interesting. You can get these powdered, soluble fibers, and you put them into a glass of water. And it just dissolves, and it looks and tastes exactly like water. It's amazing.

STANDEN: Take white bread.

MATSUNO: Yeah, so here - good source of fiber.

STANDEN: Matsuno reads off the list of ingredients.

MATSUNO: Sugarcane fiber, oat fiber. A resistant corn starch also can be fiber.

STANDEN: All - just to be clear - additives that you would not normally find in white bread.

MATSUNO: So what does it bring the fiber up to here? Again, 3 grams, because you can...

STANDEN: In the world of food labeling, 3 grams of fiber is kind of a magic number. It's the minimum amount that you can pack into a product and still have the words "good source of fiber" on the label. But that designation, says Matsuno, is a little bit generous.

MATSUNO: An apple, with the peel, is 5 grams of fiber.

STANDEN: The bigger question here is whether these fiber-fortified foods are making you any healthier. And this turns out to be one of those places where scientists know a lot less than you may think they do. For example, a lot of people think that fiber will help protect you against colon cancer. But so far, that link is not conclusive. There is a stronger connection between fiber and cardiovascular disease. Again, John Swartzberg from U.C. Berkeley.

SWARTZBERG: There's a lot of data on fiber that suggests that yeah, there may be less cardiovascular disease in people who eat a high-fiber diet.

STANDEN: In other words, people who eat lots of fruits, vegetables and legumes have lower rates of heart disease. But no one knows exactly why this is. Why do fiber-rich foods appear to prevent heart disease? Is it the fiber, or is it something else in those foods? Maybe it's a combination of things. Maybe there is no single, magic bullet. And so you have to ask...

SWARTZBERG: If we're not sure what it is in fruits and vegetables, then, as opposed to saying well, it's probably the fiber, or it's probably this or that, why not just have people eat lots of fruits and vegetables?

STANDEN: Now, some food scientists are less critical of these fiber additives. They say many Americans are always going to choose junk food over fruits and vegetables. So you might as well put some fiber in there, even if we don't really know how much benefit it's having. But what pretty much everyone agrees is this: Given a choice between fiber-fortified sugar cereal and an apple, you're better off with the apple.

SWARTZBERG: I don't want people to think that by adding things to unhealthy foods, it somehow makes them healthy. And I think that's the most important message.

STANDEN: One thing we do know about some synthetic fiber additives: too much of them can you gas. But don't expect to see that mentioned on the front of your cereal box.

For NPR News, I'm Amy Standen.

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