What Is Fiber & How Does It Work? Everything You Need to Know

May 4, 2018 at 1:21 p.m. ET
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When's the last time you thought to yourself: "I wonder if I've had enough fiber today?"

We'll venture to guess it's been a while... or you never have. And there's no shame in that. But it is important to note that dietary fiber is much more than just a crazy term or fad that can be ignored. Eating a fiber-rich diet is extremely important and absolutely imperative to keep bodily functions running smoothly.

Yet to most of us, fiber still remains a mystery. Here's exactly what it is, how it works and why you need it.

More: 10 Tips for Getting Your Digestive Health Back on Track

What is fiber?

Fiber is the part of plant foods that your body can't digest or absorb. It is also referred to as roughage or bulk.

"By classification, fiber is considered an indigestible carbohydrate," explains board certified emergency physician and a Fellow of the American College of Emergency Physicians, Dr. Elaine Rancatore.

But fiber is very different from other carbohydrates — and much lower in calories.

The benefits of fiber

Don't let the term "indigestible" throw you off. Although fiber is not digestible, it is good for the body in many ways, says naturopathic physician Wendy Wells.

"Eating fiber increases the immune system in your gut, feeds the good probiotic bacteria there, keeps the digestive lining healthy and absorbs and pulls out excess hormones, cholesterol, fat and toxins from the body," Wells says.

And pulling out those toxins is part of what make fiber so important.

"Many of the health problems we face start from a poor or sluggish digestion caused from built-up waste material in our colon," says nutrition expert Siv Sjöholm. "Fiber helps us digest and pass the foods we eat. By increasing our fiber intake, we decrease the risks of common diseases such as cardiovascular disease, cancer, diabetes and obesity."

More: These Are the Early Signs of Digestive Problems in Women

But the benefits of fiber don't stop there. Nutrition and wellness coach Michelle Pfennighaus outlined these added bonuses:

  • Fiber slows the absorption of sugar into your bloodstream to help maintain stable blood sugar levels and help prevent Type-2 diabetes.
  • Fiber lowers bad LDL cholesterol and promotes heart health.
  • Fiber helps keep you feeling full and satisfied and more in control of your appetite and weight.
  • Fiber keeps your digestive system healthy and regular, helping you to avoid constipation and the risk of diverticulitis.
  • Fiber reduces the risk of certain types of cancer, including colon and breast cancer.

The different types of fiber

There are two types of dietary fiber, and you need both.

Insoluble fiber adds the bulk needed to clean out the colon and regulate bowel movements. This fiber, or roughage, acts like a sponge. As it absorbs water, it swells inside your intestine and produces a feeling of fullness. The insoluble fiber moves through the digestive system to remove waste, toxins and materials your body doesn't need.

Soluble fiber comes from fruit, some vegetables, brown rice, beans, barley peas, lentils, oats and bran. Soluble fiber mixes with water and digestive enzymes made by the liver to create a gel. This gel works chemically to prevent and reduce the body's absorption of substances that may be harmful. It is soluble fiber that helps control blood sugar and reduces cholesterol.

More: The High-Fiber Foods You Should Be Eating More Of

How to eat more

To increase your fiber intake, try adding these foods to your diet:

  • Fruits, vegetables, beans, peas, lentils
  • Nuts and seeds
  • Whole grains

A version of this article was originally published in April 2012.

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