By Angela Haupt and Katherine Hobson, USNews.com
Mon, Feb 14, 2011
Mon, Feb 14, 2011
Hear fiber and you probably think of bran cereal, which doesn’t exactly make you salivate. But new research suggests more fiber could equal more years. Analyzing data from nearly 400,000 men and women ages 50 to 71, researchers found that those who consumed the most fiber were 22 percent less likely to die from any cause during the nine years they were studied. Men were 24 to 56 percent and women 34 to 59 percent less likely to die of heart and infectious or respiratory diseases, according to findings from the National Institutes of Health's AARP Diet and Health Study, published today in the Archives of Internal Medicine.
What is clear, however, is that participants only benefited when fiber came from grains, like oatmeal, cornmeal, and brown rice. Fiber from fruits, vegetables, and beans had no impact on death risk. "Whole grains are rich sources of fiber, but also good sources of vitamins, minerals, and other phytochemicals that may provide health benefits," Park says. And grains have powerful antioxidant and anti-inflammatory properties--another reason researchers say grain fiber is beneficial.
Clearly, "all fibers are not created equal," cautions James Anderson, an endocrinologist at the University of Kentucky-Lexington. "Different fibers have different properties." And while the latest study emphasizes grain fiber, past studies have found that fiber from fruits and vegetables can benefit heart health.
Here's a field guide to fiber sources:
Soluble fiber: Foods high in soluble fiber, so called because of its ability to dissolve readily in liquids--include oat bran, oatmeal, beans, peas, rice bran, barley, citrus fruits, strawberries, and apple pulp, according to the American Heart Association. Soluble fibers have been linked to lower levels of "bad" cholesterol. Viscous fibers found in foods like oat bran and beans seem to work particularly well because they form a gel in the gut that slows down fat formation and absorption, says Joanne Slavin, a professor of food science and nutrition at the University of Minnesota and author of the American Dietetic Association's 2008 position paper on dietary fiber. (The Food and Drug Administration allows heart disease health claims for oats, barley, and psyllium, the fiber found in Metamucil.) Soluble fibers also regulate blood glucose levels, says Anderson. But most soluble fibers, except psyllium, don't have the laxative effects that many people associate with fiber, so don't rely on them for that purpose.
Insoluble fiber: High levels of insoluble fiber, too, have been associated with a lower risk of heart disease--perhaps through other mechanisms. So while there's an ongoing debate over which types of fiber confer which heart-protective benefits, the take-home is that no one should rely solely on soluble fibers to get the maximal heart benefit. The AHA lists whole-wheat breads, wheat cereals, wheat bran, cabbage, beets, carrots, brussels sprouts, turnips, cauliflower, and apple skin as foods high in this type of fiber. Unlike soluble fiber, it doesn't dissolve in liquids or form a gel but instead passes through the digestive tract pretty much unchanged. Because insoluble fiber hustles things along in the digestive tract, it's also a good source of relief if you're constipated. In addition, insoluble fiber (and to some extent, the soluble kind) may help you feel fuller and possibly help weight control.
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.
