Fiber does more than aid digestion. It supports health in a host of other ways. Learn about the many types of fiber, where to find them, and why they matter.
“Try to get more fiber. Eat fiber-rich foods. Maybe some fiber will help.” You’ve most likely heard similar advice before. Yet, despite all this advice, about 95% of Americans don’t eat enough fiber. You need at least 25 to 35 grams of fiber per day to stay healthy.
Maybe the motivation to eat more fiber can be found in understanding the different types and the many roles that they play in your health. That’s right—fiber impacts more than just your gut. In fact, it’s one of the most essential nutrients, supporting weight management, heart health, brain function, and more.
Fiber is found mainly in plant-based foods such as fruits, vegetables, whole grains, and legumes. With this range of options, it’s not too tricky to find tasty, fiber-rich foods. But what exactly is fiber? And what kinds are there?
Defining dietary fiber
Fiber is a type of carbohydrate that the body can’t digest. It passes through the digestive system without breaking down. Your body keeps it intact on purpose, which is helpful because fiber adds bulk to help move digestion along. Plus, because fiber isn’t fully digested, it doesn’t cause spikes in blood sugar in the same way as other carbs do.
Most carbohydrates break down into sugar molecules called glucose, which causes blood sugar to rise and gives your cells a spike in energy. But, since fiber isn’t absorbed this way and slows digestion of other carbs, it helps keep blood sugar steady. Instead of being used for energy, fiber hangs out in your digestive system a little longer to support gut health and keep you full. Your body may not be able to break down fiber—but the guide below can explain why this is actually a good thing for your health.
Types of fiber
There are 2 main types of fiber that keep things running smoothly—soluble fiber and insoluble fiber. They’re grouped together on nutrition labels as “dietary fiber.” Yet not all fiber works the same in the body. Here’s an overview of the 2 main types of fiber, their subtypes, and foods they are found in. Most plant foods have a mix of both, just in different amounts.
Health perks from soluble fiber
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Slows digestion. Soluble fiber dissolves in water during digestion. When it dissolves, a gel forms, which then works to slow digestion. This process is how soluble fiber helps lower blood sugar and trap LDL cholesterol, so less is absorbed.
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Protects heart and artery health. Soluble fiber plays a broader role in the body besides supporting digestion and gut health. Some types of soluble fiber help lower the risk of heart disease and artery issues. They do this by slowing the buildup of plaque in arteries—a key factor in preventing heart problems.
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Enhances gut health. Soluble fiber may be easier on your gut than insoluble fiber because it forms a smooth gel rather than rough bulk. This helps ease constipation. It also regulates bowel movements over time rather than speeding up digestion. Plus, the soluble fiber gel feeds helpful gut bacteria, boosting overall digestion and gut flora balance. You may hear soluble fiber called by these more technical names below:
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Beta-glucans. These fibers, found naturally in oats and barley, are key to forming the digestive gel. They are highly fermentable, so they act as prebiotics. Prebiotic fibers feed helpful gut bacteria. Most prebiotics are a type of fiber, but not all fiber is prebiotic.
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Pectins. These highly fermentable fibers are found in many fruits. They may help slow digestion and stabilize blood sugar.
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Inulin. This type also works as a prebiotic. It’s found in onions, asparagus, chicory root, and Jerusalem artichokes.
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Resistant starch. A fermentable fiber found in legumes, potatoes, and pasta, this type also has prebiotic effects.
Foods with soluble fiber:
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Oatmeal
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Chia seeds
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Flaxseeds
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Psyllium, a type of fiber supplement
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Beans, lentils, and peas
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Apples, oranges, and berries
Health perks from insoluble fiber
Insoluble fiber does not dissolve in water. It actually absorbs it. So, by not breaking down during digestion, it creates bulk in the stool and helps move food through your digestive tract more quickly. This process helps encourage bowel movements and prevents constipation. The bulk created by insoluble fiber can also help form larger, softer stools.
As you age, constipation may become a more frequent challenge. So, make sure you get a consistent amount of insoluble fiber. But also keep in mind that speeding up digestion can irritate the intestinal lining and cause bloating if insoluble fiber is eaten in large amounts. So spread your intakes out over all your meals throughout each day.
Here are the types of insoluble fiber:
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Cellulose. This is a type of fiber found in the cell walls of plants. It absorbs water to help keep things moving as you digest.
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Lignins. These have a natural laxative effect and trigger the release of digestive fluids in the colon, adding bulk to stool. These are found naturally in whole grains and seeds like flax, sesame, and sunflower seeds.
Foods with insoluble fiber:
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Wheat bran
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Vegetables
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Whole grains like quinoa, brown rice, and barley
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Almonds and walnuts
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Sunflower seeds
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Potatoes with skin
Additional benefits of dietary fiber
Fiber not only supports digestion, it also lowers the risk of many kinds of disease. Plus, it helps counteract many of the changes that come with age—slower digestion, shifting metabolism, and risk of chronic disease.
Research shows that fiber may help prevent heart disease, diabetes, and some cancers. These lower risks may be due to fiber’s ability to lower LDL cholesterol and prevent blood sugar spikes. Fiber also helps you feel full longer. This keeps your energy steady and prevents overeating, helping to support a healthy weight. Studies also show that eating a diversity of fiber helps nourish the gut microbiome and may contribute to longevity.
Fiber supplements
You’ve probably come across the plethora of supplements that line grocery store shelves these days. Psyllium husk is a common plant fiber that’s added to foods like cereal and comes in supplement form. But before you reach for a fiber supplement, keep in mind that whole foods are always the best first option for getting nutrients—including fiber. Whole food offers an array of fiber types and other nutrients. This means they support your overall diet quality and long-term health.
Talk to your health care provider before trying a fiber supplement. They can recommend a specific one to meet your needs. Also, fiber supplements can cause stomach discomfort and gas, and your doctor can help you find ways to minimize these digestive upsets.
How much fiber do you need?
As with many things, nutrition experts point out that more is not always better when it comes to fiber. The key is eating a variety of fiber-rich foods. It’s recommended that adults eat 25-35 grams of fiber per day to stay healthy from brain to belly. Men older than 51 need 30 grams per day and women need 21 grams per day.
You may need more or less, depending on any health conditions you have or medications you take. In fact, as you age, you may be eating less fiber than you realize. Changes in appetite, taste, or medications can make eating less appealing. So, let’s look at how you can make sure that you’re meeting your fiber needs.
How to add more fiber to your diet
The key here is to increase your fiber intake gradually so as not to overwhelm your body (or your pantry).
Water intake and fiber intake also go hand in hand—so make sure you’re staying hydrated. Without enough water, insoluble fiber can be hard to pass, and soluble fiber can’t fully dissolve. Plus, dehydration is more common in older adults, so this becomes extra important as you age. You may even be eating enough fiber—but if you are dehydrated, your digestion will most likely still suffer and not improve. If, however, you focus on choosing fiber-rich foods at each meal and pair them with water, you’re one step closer to a balanced body.
Watch for changes in your digestion when adding fiber to your diet. Use these tips to help you make sure you’re getting a good amount of fiber:
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Replace white bread, pasta, and rice with whole grains. Some examples of whole grains are brown rice, quinoa, steel-cut oats, barley, and farro.
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Snack on whole fruits and vegetables.
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When choosing cereals, look for those that list a whole grain as the first ingredient.
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Check the Nutrition Facts label and choose foods with 20% or higher of the Daily Value (DV) for fiber.
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Add high-fiber foods to meals you already eat. For example, toss some flaxseeds and chia seeds on your yogurt. Include veggies in your soups, pasta, casseroles, and more.
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At least once a week, substitute meat with beans or legumes. Or just enjoy them as a side.
With fiber, it’s all about balance and variety, not perfection. Soluble fiber and insoluble fiber each provide unique benefits. But it’s important not to hyperfocus on one type over another. Just keep in mind that even small shifts in your daily meals can have a major impact on your health and comfort.
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This article was written by Celina Johnson, edited by Gail Olson, CMT, HHP, and clinically reviewed by Elizabeth Thompson, MPH, RDN, on June 5, 2026.
