Dietary Fiber and Key Points to Know About



Everyone’s heard about fiber and how they need it for good health. People say bananas help keep you regular because of the fiber. And many think changing to whole wheat bread is the best way to add more fiber to their diets. However, beyond those random facts, you might realize that you don’t really know that much about dietary fiber. 


You might not understand why it’s supposed to be desirable, what it does, or if it actually does anything at all. We’re here to help! Here’s a guide to some key things you might want to know about fiber but are afraid to ask.

What is Fiber?

Fiber is a subset of compounds the human body cannot digest. That sounds sort of like a bad thing or at least an unnecessary one, but it’s imperative! According to Harvard’s Nutrition Source website, fiber helps keep digestion moving and regulates the absorption of sugar and cholesterol. 


This is counterintuitive until you think about it for a minute. As your body digests food, less and less remains until getting at what’s left is more complicated than drinking the last quarter-inch of a drink through a straw. So fiber stays in the system, not being digested, to push the food you need forward through your digestive tract. It’s like if you had a lot of small ice in that same cup—it wouldn’t go into the straw, but it would raise the level of the drink so you could get more out. 


There are two types of fiber: soluble and insoluble. Soluble fiber dissolves in water and keeps you feeling full for longer while helping the body regulate blood sugar levels. Insoluble fiber does not dissolve in water, and its functions are promoting colon health and easing constipation.


In addition to aiding with digestion, fiber serves many other purposes, including the following:


Most Americans do not get the amount of fiber they need each day. The recommended serving of fiber is 21 to 26 grams a day for a woman and 30 to 38 grams for a man. Children need 19 to 26 grams, depending on their age. In the United States, most people get less than 15 grams of dietary fiber daily. 


In addition, processed food has a lot of its fiber removed. So even starchy foods, like potatoes and flour, have a lot less fiber when eaten as potato chips or white bread than if consumed in the form of baked potatoes or whole grain bread. Cutting out refined, processed food and opting for whole fruits and vegetables is one of the easiest and healthiest ways to get more fiber into your diet. Here are some of the high-fiber foods you should try. (The following nutritional information comes from the Mayo Clinic.)

7 High-Fiber Foods to Add to Your Diet

1. Beans and Legumes

Beans and legumes have some of the highest amounts of fiber of all the foods we know about. The top fiber-containing food in this category is split peas, which are legumes that contain a whopping 16 grams of fiber in a single cup. Others, like lentils and black beans, still have around 15 grams; even canned baked beans have 10 grams of fiber per cup. Green peas are near the bottom of the list, but they’re still pretty good, with 9 grams. So if you’re feeling short on your fiber intake, eating from this category is the fastest way to get your numbers up!

2. Avocados

Avocados are, frankly, an absurdly healthy food. They have high quantities of good fats, more potassium than bananas, tons of folate (required to digest B vitamins and for good cell functioning), vitamin C, and more. So is it any wonder they also have a great fiber content? Half of a medium avocado averages around 4.6 grams of fiber. They’re easy to toss into a smoothie, salad, or sandwich, so it can be effortless and fun to get your daily recommended fiber in—as well as practically everything else!

3. Berries

A small handful of berries is a surprisingly efficient way to get some fiber into your diet. A single cup of raspberries has 8 grams of fiber, over half as much as an entire avocado! Of all the berries, raspberries have the highest concentration, with strawberries and blackberries right behind them. 


Try to measure out one or two cups of your favorite berry or a mixture to carry with you, and snack on them throughout the day.

4. Whole Grains

As mentioned above, whole grains are rich in fiber, but heavy processing strips almost all of it away—which is why white bread is white instead of brown like the wheat it comes from. A slice of whole wheat bread only has about 2 grams of fiber. Check bread labels for the words “whole grain” because it also tends to be less processed in addition to containing more fiber. 


When buying other products, look for whole grain wheat or barley (with 6 grams per cup) for the best results. Whole oats are also pretty good because they have about 5 grams per cup! Brown rice can be added to almost any meal, providing 3.5 grams per cup. 

5. Broccoli 

This is an excellent option if you’re a broccoli fan! With 5 grams a cup, broccoli can easily give you a fiber boost when added to various dishes or snacked on raw or roasted. As one of the cruciferous vegetables, it is also one of the richest in phytonutrients and provides the body with glucosinolates, which promote the health and diversity of your gut bacteria.

6. Nuts and seeds

Nuts are reasonably rich in fiber, and they’re also high in healthy fats, so there’s more than one reason to pick them up for a snack! Almonds, the highest-fiber nut, have 3.5 grams an ounce, with pistachios and other nuts not far behind them with an even 3 grams. Consuming 8 ounces of nuts, equal to one cup, you’d have almost your entire daily fiber intake! Try snacking on them throughout the day or adding a few handfuls to your varied diet of fiber-rich fruits and veggies. 


Chia, flax, and hemp seeds are packed with both soluble and insoluble dietary fiber, along with health-promoting omega-3 fatty acids. Seeds, including sunflower, pumpkin, and sesame seeds, also contain fiber—and even protein-rich quinoa is a seed that provides 5 grams of fiber per cup.

7. Popcorn

Many of you will be happy to hear that popcorn is a solid fiber source! An average serving of 3 cups has 3.5 grams of fiber. With this tasty snack, opt for the products free of excess butter, sugar, and preservatives to keep it as healthy as possible.

What Other Forms Can You Take Fiber In?

Fiber can also be consumed in pill or powder supplements. This option can be suitable for some people, although it is best to get your daily fiber needs from eating a healthy, plant-rich diet.


The composition of your gut microbiome is made up of bacteria that thrive in their present environment, which is what you currently consume—healthy or not. And if that includes a less than optimal fiber intake, adding too much fiber at once will lead to symptoms like gas and bloating. To prevent this, start slowly, particularly if you are taking the fiber supplement for constipation. Adjust the dosage to meet the amount of fiber you’re already getting so it doesn’t cause uncomfortable symptoms, and increase it over time to achieve optimal levels while you work on increasing your dietary fiber. And make sure to up your fluid intake whenever you take fiber supplements to keep things moving efficiently through the digestive tract.


If you occasionally get constipated, then you can use fiber as a maintenance therapy in addition to consuming a healthy diet. In general, monitoring your stools can help you be aware of times when your fiber intake tends to be on the low side. Having harder, less frequent stools is a sign you need to consume more fruits, vegetables, and water.

What to Look For in a Fiber Supplement

Try to make sure the supplement you choose has been third-party tested. Dietary supplements are not regulated as medications by the FDA and can be ineffective or contaminated with dangerous material. Also, make sure it’s the right kind of fiber for your needs. For example, if you’re looking for fiber because of digestive issues, be aware that there are two kinds. Soluble fiber makes your stool firmer, and insoluble fiber makes it softer. The two are usually mixed in nature but may not be in supplements, so make sure you choose the one you need. 


Ideally, it is best to get your fiber in as an integral part of a healthy, whole-food, plant-rich diet. That way, you will receive all of the natural beneficial compounds contained in plant foods, such as disease-preventing anti-inflammatories, antioxidants, and phytonutrients. Dietary fiber also supports a healthy gut and the diversity of its microbial colonies, which then improve your overall health and resistance to disease. Take fiber supplements only if necessary and in consultation with your health professional.