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You probably already know that fiber helps with digestion. Did you know it can have big benefits for your heart health too?

"Studies have shown that foods that have a lot of fiber are clearly associated with lower risk of heart disease," says Alice H. Lichtenstein, DSc, American Heart Association spokeswoman and director of the cardiovascular nutrition research program at Tufts University's Jean Mayer USDA Human Nutrition Research Center on Aging.

How does dietary fiber help us? Is it something in the fiber itself, or are the benefits less direct? Here's what you need to know about fiber for heart health and low cholesterol.

Fiber for Heart Health: The Benefits

Dietary fiber is the name for certain carbohydrates -- from vegetables, plants, and grains -- that the body can’t digest fully. Evidence for the benefits of fiber for heart health is quite strong. It's been established in numerous studies. Diets high in fiber are associated with:

  • Lower LDL (“bad”) cholesterol levels
  • Lower blood sugar levels in people with diabetes
  • Lower blood pressure in people with high blood pressure
  • Lower risk of heart disease
  • Lower risk of diabetes
  • Healthier weights and lower rates of obesity

As a treatment, dietary fiber for heart health might seem strange. Fiber is indigestible. It can't be absorbed through the intestines. Unlike a dose of aspirin or fish oil -- which work their benefits inside the bloodstream -- fiber is just passing through.

How does something we can't digest have such a big benefit for our hearts? The benefits of fiber for heart health may lie in how it prevents the intake of less healthy foods:

  • Fiber as a binding agent. One of the common theories about fiber is that it binds with cholesterol in the intestines. The idea is that when fiber is converted into a gluey paste in your digestive tract, it sticks to the cholesterol and prevents it from being absorbed into the body, where it could have gone on to clog your arteries.

This explanation has detractors. "There's just not good evidence to support that idea that fiber binds with cholesterol and absorbs the fat," says Edgar R. Miller III, MD, PhD, associate professor of medicine and epidemiology in the department of medicine at Johns Hopkins University.

  • Fiber as a substitute. Miller believes in a simpler theory to explain the benefits of fiber for heart health: If you're having a bowl of oatmeal for breakfast, you're not having a plate of bacon.

It's simple substitution. People who eat a lot of dietary fiber -- which comes from plants, has no cholesterol, and is low in calories -- are probably eating less fatty, high-calorie foods. So the benefits of high-fiber foods aren't in the fiber itself; they're in what you’re not eating when you’re eat them, Miller says.

  • Fiber for weight loss. There's a reason that a high-fiber diet is a cornerstone of many weight loss plans. High-fiber foods tend to be low in calories. They take longer to eat. They make you feel full sooner and for longer. If you're eating more fiber, you're eating less of the stuff that causes weight gain -- and keeping a healthy weight is crucial in keeping your heart healthy.

High-Fiber Super Foods

From fruits to nuts, see the best source of fiber in natural foods.
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Dietary Fiber Poll

What provides most of your fiber?

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