General Nutrition

Dietary fiber: what is it & why is it important?

November 14, 2023

Written by

Medically reviewed by Rita Faycurry, RD

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Key Points

  • Dietary fiber plays a significant role in managing your overall health.
  • High-fiber foods help control blood sugar, manage weight, lower bad cholesterol, relieve constipation, foster healthy gut bacteria, and more.
  • Adults should aim for about 25-30 grams of fiber per day.

Fiber feels like something we all know about – but what is it, really? And why is it a big deal? Fiber is an underrated nutrient that plays an essential role in maintaining health, supporting healthy digestion, and even preventing disease. In fact, in countries with high amounts of fiber in the average diet, the overall rates of chronic disease are low. Dietary fiber is a lot like a broom in your pantry: it helps sweep out things your body doesn't need, ensuring your internal systems stay clean and efficient.

Let’s talk about this nutrient and the role it plays in your overall health.

What is dietary fiber?

Dietary fiber includes the parts of plant foods that your body can’t digest. While the carbohydrates, fats, and proteins of these foods are broken down and absorbed by the body, fiber passes through your digestive system unabsorbed and out through your body.

Fiber comes in two forms:

  • Soluble fiber dissolves in water to form a gel-like substance. Soluble fiber can help lower blood cholesterol and glucose levels. It is found in apples, citrus fruit, oats, peas, beans, carrots, and barley.
  • Insoluble fiber doesn’t dissolve in water, which means it can help move material through your digestive tract. This can help with irregular bowel movements or constipation. Insoluble fiber appears in whole wheat flour, nuts, beans, and several vegetables, like potatoes and cauliflower.

Both types of fiber have benefits, so be sure to eat a variety of foods to get a healthy mix of each fiber.

Benefits of fiber

Fiber is perhaps best known for its ability to support healthy bowel movements. It increases the size and weight of stool while also softening it, making it easier to pass and helping prevent constipation. Fiber supports bowel health overall and can even lower the risk of colorectal cancer.

Dietary fiber can also keep your blood sugar under control after eating, which can improve blood sugar levels. Soluble fiber in particular slows sugar absorption, offering significant benefits for people with diabetes and those at risk. Insoluble fiber, as part of a healthy diet, may also reduce the risk of developing type 2 diabetes.

Have high cholesterol? Increasing your fiber intake is a great way to decrease “bad” cholesterol (low-density lipoprotein, also known as LDL). Soluble fiber is particularly effective for this, and just 5-10 grams per day can decrease LDL cholesterol. Oatmeal and oat bran are common suggestions to boost soluble fiber.

And finally, fiber can be a great tool for weight management, as high-fiber foods tend to be more filling and take longer to digest. This sense of fullness tends to leave you feeling satisfied and satiated for a longer period of time. Think about how quickly you feel hungry after eating simple carbohydrates, like white bread, versus fruit or starchy vegetables. The difference lies in the amount of fiber!

Fiber-rich foods

Fiber-rich foods primarily come from plants and include:

  • Vegetables - dark-colored vegetables in particular are high in fiber, like carrots, beets, broccoli, collard greens, and artichokes
  • Fruits - bananas, berries, oranges, apples (with the skin on – that’s where the most fiber is!), and mangoes are specifically high in fiber, but all fruits have some amount of fiber
  • Whole grains like brown rice, wild rice, and barley, as well as whole-grain bread
  • Nuts
  • Oats
  • Beans
  • Seeds

Here’s an example of foods you can include throughout the day to reach the daily recommended fiber amount:

Breakfast: 1/2 cup high-fiber cereal (10 grams), 3/4 cup raspberries (6 grams)

Lunch: 2 slices of whole-grain bread (4 grams); 1 small apple (2 grams)

Dinner: 1 cup of broccoli (5 grams); 1 cup of brown rice (3 grams)

Total: 30 grams fiber

So, how much fiber should you be eating a day? For adults, nutritionists generally recommend about 25-30 grams. Your exact range depends on your age, sex, and other factors. When working with a registered dietitian, you can figure out your ideal fiber intake based on their professional recommendation.

How to increase your fiber intake

Only about 5% of Americans meet the recommended amount of daily fiber intake – so chances are, you probably need to eat more fiber! Simple swaps can also help add fiber to your meals. Opt for whole-wheat bread instead of white, eat fruits with the skin on rather than drinking fruit juices, and add berries or nuts to your cereal or yogurt. Fresh or dried fruits make a great snack, and adding chickpeas or kidney beans to rice dishes or salads is a tasty way to up your fiber intake.

As you increase your fiber intake, remember to do it slowly to give your body time to adjust. And don't forget to drink lots of water. Fiber works best when it absorbs water, making your stool soft and bulky.

The benefits of dietary fiber are vast, and adding more to your diet can be a positive change toward healthier living. But if you're unsure where to start and want personalized advice, a registered dietitian can help. Fay Nutrition connects you with board-certified RDs who are covered by your insurance so you can get the care you need without a significant cost barrier. Click here to get started.

The views expressed by authors and contributors of such content are not endorsed or approved by Fay and are intended for informational purposes only. The content is reviewed by Fay only to confirm educational value and audience interest. You are encouraged to discuss any questions that you may have about your health with a healthcare provider.


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Written by

Rita Faycurry, RD

Medically Reviewed by Rita Faycurry, RD

Rita Faycurry, RD is a board-certified Registered Dietitian Nutritionist specializing in clinical nutrition for chronic conditions. Her approach to health is centered around the idea that the mind and body are intimately connected, and that true healing requires an evidence-based and integrative approach that addresses the root cause of disease. In her books and articles, Rita offers practical tips and insights on how to care for your body, mind, and spirit to achieve optimal health and wellness.