What Is Fiber, and Why Is It Good for You? Here Are 6 Health Benefits

Fiber is a carbohydrate found in plants. Even though your body can’t digest fiber, it’s still an essential part of a nutritious diet. Fiber helps food move through your bowels, but it has many other health benefits, including protecting you from a wide range of medical conditions. 

But the truth is: Most Americans don’t eat enough daily fiber. There are many reasons why. Some think fiber-rich foods don’t taste good. Other people think “healthy” foods are too expensive or complicated. 

Packaged foods can also be misleading. For example, over 30% of breakfast cereals claiming to be “whole grain” are not actually good sources of dietary fiber. 

The good news is, not only is fiber good for you — but it’s also easy to get, inexpensive, and tasty. And for most people, eating more fiber is one of the easiest things you can do to boost your health, lose weight, and lower your risk for disease. 

What is fiber?

Fiber is found in plant foods. It’s also sometimes called “bulk” or “roughage.” You get fiber by eating: 

• Fruits

• Veggies

• Whole grains

• Beans

• Lentils

• Nuts

• Seeds 

• Fiber supplements

Fiber is also a carbohydrate, a type of macronutrient. Macronutrients are nutrients that your body needs (and uses) in large amounts every day. Other macronutrients include:

• Proteins

• Fats and cholesterol

• Water

Most types of fiber don’t have a lot of calories and aren’t a source of nutrition per se. But fiber still plays many important roles in your body (more on this below).

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What are the different types of fiber?

There are two types of fiber: soluble and insoluble. Most fiber-rich foods have a mix of both. Both types help you make and pass stool. The type of fiber you eat doesn’t matter as much as the quantity. 

Soluble fiber: This type of fiber absorbs water like a sponge. It forms a gel in your gut, slowing down digestion. It also helps you feel full and adds softness to your stool. It’s found in:

• Nuts

• Seeds

• Lentils

• Peas

• Certain fruits and veggies

• Some whole grains, like oats and barley

Soluble fiber is also the type of fiber in over-the-counter psyllium supplements, like Metamucil. 

Insoluble fiber: Insoluble fiber does not absorb water. It bulks up your stool and helps food and waste pass more efficiently through your gut. It’s found in vegetables, whole grains, and wheat bran. 

Is fiber good for you?

Yes, according to the National Institutes of Health (NIH), fiber is good for both your digestion and overall health. It helps to keep your gut healthy, balance blood sugar, and lower cholesterol.  

What does fiber do for the body?

Researchers have found evidence that eating fiber can potentially:

• Help you have easy-to-pass bowel movements

• Lower your risk of colon cancer, Type 2 diabetes, and heart disease 

• Lower your risk of diverticulitis 

• Lower your risk of hemorrhoids

• Help control your blood sugar and cholesterol levels

• Help you lose weight, or maintain a healthy weight

• Help you live longer

• Boost your immune system and protect you from severe flu or COVID-19

• Nourish a healthy gut microbiome

Let’s take a closer look at these. 

1. Fiber and your gut health

Fiber keeps your digestion moving and helps your body get rid of waste. Fiber also helps to keep your gut healthy and may even protect the cells of your gut. 

Fiber provides food for the microbes in your gut. These microbes digest the fiber you eat and turn it into healthy small molecules. Some of these molecules are called short-chain fatty acids (SCFAs). In research studies, SCFAs are connected to a healthier metabolism. They may also protect you from having other health problems, like colon cancer.  

Giving your microbes enough fiber to eat can also protect your gut. Your gut is lined with mucus — a watery, slippery substance. This mucus layer protects your body and helps with digestion. If your microbes don’t have enough fiber to eat, they will eat the mucus. Eating fiber keeps your microbes well-fed and encourages a plump and healthy mucus layer. 

2. Fiber and constipation

Constipation is a health condition where you have trouble passing stool. This can happen when food and waste move too slowly through your bowels. It can also happen if your stool is too hard and dry, making bowel movements painful. 

A high-fiber diet can help with constipation. In one research study, 77% of people with chronic (ongoing) constipation got better when they ate more fiber. Many other research studies have shown that fiber can help you have more regular bowel movements. 

Soluble fiber helps you to better absorb water, which makes your stool softer. Soft stool moves through your gut more easily and takes less effort to eliminate. And insoluble fiber helps to bulk up your stool, making it easier to pass. 

3. Fiber and your heart health

There’s a strong link between fiber and cardiovascular (heart and blood vessel) health. In 2017, scientists looked back at almost all of the studies done in the past 37 years on heart health and fiber. They found that people who ate more fiber were less likely to get sick — or die — from cardiovascular disease. 

Why is fiber good for your heart? It may be able to help control your cholesterol, blood sugars, weight, and blood pressure. These are all very important for heart health.  

4. Fiber and weight loss

People who eat a high-fiber diet tend to weigh less. This may be because fiber helps you feel full, and stay full — but without adding extra calories. 

If you have extra weight or obesity, fiber can also help you lose weight. In a study of 240 adults, people who ate 30 g of fiber lost weight and kept it off after one year. And in a meta-analysis of 12 different studies, people who ate more fiber for 2 to 17 weeks had a lower body mass index and lost more body fat than people who didn’t.   

5. Fiber and blood sugar

Fiber can help you manage your blood sugar. It slows down the absorption of sugar in your gut, preventing blood sugar spikes. This can make it easier to manage your blood sugar levels, especially if you have diabetes. 

A high-fiber diet can also protect you from getting Type 2 diabetes. In a large study of 75,000 adults, eating fiber lowered the risk of developing diabetes — especially when the fiber was from grains. And, in an older study of 65,000 women with diabetes, women who ate a high-sugar, low-fiber diet were two and a half times more likely to get diabetes compared with women who ate lots of fiber. 

6. Fiber and cancer prevention

According to the American Institute for Cancer Research, eating at least 30 g of fiber a day can lower your colon cancer risk. In fact, every extra 10 grams of fiber may lower your cancer risk by 7%. 

There’s also evidence that fiber from whole grains may be more helpful than other sources of fiber like fruits, vegetables, and beans. But more research is needed in this area. 

How much fiber should I eat?

The National Academy of Medicine recommends aiming for 14 g of fiber in every 1,000 calories you eat. 

For adults between ages 19 to 50, this works out to about:

• 25 g per day for females

• 38 g per day for males

How can I add more fiber to my diet?

Eating fruits, vegetables, and whole grains is the best way to add fiber to your diet. The closer the food is to its “natural” form, the more fiber it will contain. 

For example, here’s a comparison of the fiber in different apple foods:

• Whole apple (with peel): 4.4 g fiber

• One half cup of applesauce: 1.4 g

• Apple juice: no fiber

Other tips for increasing your fiber intake include:

• Aim for at least 4 to 5 servings of fruits and veggies a day, and leave the peels on them.

• Eat whole grain bread instead of white.

• Start the day with a high-fiber breakfast, like oatmeal or bran cereal.

• When you eat packaged products, choose items with at least 5 g of fiber per serving.

• Substitute animal proteins (like fish, chicken, and beef) with high-fiber plant-based proteins like lentils and beans.

• Experiment with adding more plant-based meals and snacks to your diet.

• Consider tracking your fiber with the Power Plate Quick Fiber Check. 

And keep in mind: If you’re increasing your daily fiber, it’s important to do it gradually over several weeks. Eating a lot of fiber suddenly can cause gas, bloating, and cramping. These symptoms tend to go away over time as your gut microbiome gets used to handling larger amounts of fiber. Drinking water can also help.

Fiber-fortified foods and fiber supplements

There are many fiber-fortified (extra fiber added) foods and supplements on the market. These can help to boost your fiber intake if you’re having trouble getting enough from food. 

Keep in mind, though, that many fiber-fortified foods and supplements only contain one type of fiber. And unfortunately, these types of products might not have the same health benefits as whole foods. 

Best foods for a high-fiber diet

According to the Dietary Guidelines for Americans, top food sources of fiber include:

• Whole fruits and vegetables

• Beans and lentils

• Whole grains

• Nuts and seeds

Best foods for a low-fiber diet

Fiber is great for most people. But sometimes your healthcare provider might actually recommend a low-fiber diet. This is usually because of a medical situation or health condition. A low-fiber diet decreases the bulk in your gut, allowing it to rest. 

Your healthcare provider may recommend a low-fiber diet for you if you:

• Are having a medical procedure or surgery on your gut

• Are having a flare-up of a chronic (ongoing) gut condition, like Crohn’s disease, irritable bowel syndrome (IBS), or diverticulitis

• Have a blockage in your gut

Low-fiber foods include:

• Meat, fish, and chicken

• Tofu

• Dairy and eggs

• White breads and refined grains

• Some well-cooked or canned fruits and vegetables

If you have questions about whether a low-fiber diet is right for you — and what to eat — talk to your healthcare team for guidance.

Why trust our experts?

Written by:

Sarah Gupta, MD

Sarah Gupta, MD, is a licensed physician with a special interest in mental health, sex and gender, eating disorders, and the human microbiome. She is currently board certified by the American Board of Psychiatry and Neurology.

Edited by:

Samvida Patel, MNSP, INHC

Samvida Patel, MNSP, INHC, is a health editor at GoodRx. She is a nutritionist and integrative nutrition health coach with over 8 years of experience in health communications.

Reviewed by:

Patricia Pinto-Garcia, MD, MPH

Patricia Pinto-Garcia, MD, MPH, is a medical editor at GoodRx. She is a licensed, board-certified pediatrician with more than a decade of experience in academic medicine.

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