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7 benefits of fiber for gut health and more

Written by John Davis

Last updated: April 11, 2023

Fiber is a core part of any healthy diet. It provides sustenance for healthy bacteria in your gut, and plays a role in regulating your weight, appetite, and blood sugar. On top of that, it’s best-known for helping with regular, healthy bowel movements.

Despite its importance, though, most people don’t get enough fiber in their diet. If that includes you, a fiber supplement is a smart idea.

Either on its own or mixed into a shake or smoothie, fiber supplements have solid evidence backing their efficacy for gut health, weight loss, and more. Here’s everything we know about the research-backed benefits of fiber supplementation.

Fiber benefits

1. Adequate fiber intake is key for digestive health

Fiber is the indigestible carbohydrate content of food, and plays important roles in cultivating vibrant health, especially in our digestive system.

Nutritional experts are continually advising us to include more fiber in the diet. We’ve been told we don’t get enough (1), and eating more fiber is supposed to have benefits across the board, from preventing cancer and heart disease to lowering cholesterol levels.

2. Both soluble and insoluble fiber are necessary

The reasons for including plenty of high-fiber foods are more complex than you might think.

Two kinds of fiber are found in the foods we eat; water-soluble fiber obviously dissolves in water, and insoluble fiber does not. Soluble fiber is digested by bacteria in the gut, and this process has a number of beneficial effects on the system (2).

The soluble fiber found in foods like nuts, seeds, oat bran, lentils, beans and certain fruits and vegetables attracts water and turns to a gel, slowing digestion. The insoluble fiber found in foods like whole grains and vegetables bulks up the stool, and may help foods pass through the digestive system more quickly (3).

3. Fiber helps your healthy gut bacteria flourish

Each of us has around a hundred trillion gut flora living in our digestive tract, ten times as many as the number of cells in our bodies. Gut flora enjoy a safe environment, and in turn, perform services for the body it can’t do on its own.

These bacteria affect everything from brain function and immune response to blood sugar and weight (4, 5, 6, 7).

Since most nutrients are absorbed into the bloodstream quickly, intestinal bacteria are last in line to get nutrients from food we eat.

Gut bacteria have the ability to digest fiber, so when the fiber from our diets finally makes it to the large intestine, they go to work digesting what’s been moved along mostly unchanged up to that point.

4. Fiber is a prebiotic nutrient

As fiber gets partly digested, it releases prebiotic nutrients, which increase what’s called the “friendly” bacteria population; when certain species of bacteria thrive in this inner environment, they can positively or negatively affect ratios of lean body mass to body fat (8).

Butyrate is one of these byproducts, and has been associated with improved colon health (9, 10).

The short-chain fatty acids produced by the digestion of fiber appear to have positive influences on patients with Crohn’s disease and irritable bowel syndrome (11).

5. Fiber helps with blood sugar control

Different kinds of fiber can have different effects on digestion, as well as on sensitive regulatory processes like blood sugar levels.

High-fiber foods are usually lower on the glycemic index, so even vegetables high in natural sugars like sweet potatoes, carrots, parsnips, and beets don’t cause significant spikes in blood sugar because it takes longer to digest them (12).

Low-fiber foods are often higher on the glycemic index, which can cause problems for diabetics and others who want to avoid the harmful effects of blood sugar spikes.

Foods high in fiber take up more space in the stomach, causing a feeling of satiation, which sends the signal to stop eating. The obvious result of this effect is that a focus on high-fiber foods in the diet may result in a lower overall intake of calories.

6. Fiber can help you lose weight

In one recent study, women were randomly assigned to follow two diets; one was a standard low-fat diet, and the other diet allowed the consumption of as many high water content fruits and vegetables as the subjects desired.

Both groups lost weight: about 14 pounds average for the low fat group, and 17 pounds for women who ate their fill of added foods, all of which were rich in fiber. The women eating plenty of fruits and veggies ate more food by volume, but consumed fewer total calories (13).

7. Fiber can help prevent chronic disease

Research suggests that eating more fiber may be a contributing factor to why plant-based diets have been successful in dropping cholesterol levels, as well as triglyceride measurements and blood pressure.

These conditions jack up the risk of coronary heart disease, so upping fiber intake may be useful in treating patients at high risk for cardiovascular problems (14).

Adequate dietary fiber has been associated with a reduction in the risk of developing cardiovascular disease, too (15). A study issued by the National Institutes of Health found that people with more fiber in their diets had a lower incidence of cardiovascular disease (16).

Fiber side effects

Fiber can cause bloating and gas if you’re not used to them. Fiber supplements are all-natural, but they can cause bloating and gas—especially if you aren’t used to a high fiber diet.

Because of the symbiotic relationship between fiber and probiotic bacteria, your bacteria in your gut can quickly proliferate when provided with a lot of fiber. The result? Gas and bloating.

Gradually ramp up your dosage to avoid GI side effects. There are a few ways to avoid these side effects. The first, and most simple, is to be patient. As your body adjusts to higher fiber intake, and as your bacterial populations stabilize, you’ll likely have fewer problems with gas and bloating.

f that’s not enough, you can try taking a probiotic supplement to restore balance to your body’s microbiome. Another strategy to try is taking a digestive enzyme to break down some of the other compounds in your diet that might be causing gastrointestinal complaints.

Finally, you can parse out your daily fiber intake into smaller, more frequent doses, versus taking it once per day. It’s a bit less convenient, but you’ll still get the same benefits, potentially with fewer side effects.

Fiber dosage

Aim for 10-15 grams per day of supplemental fiber, minimum. On average, Americans and other citizens of Western countries only average about 15 grams per day. However, the amount of fiber recommended by the American Heart Association is double that amount, suggesting that an appropriate dose might be 10-15 grams per day.

Most research uses around 12 grams per day. Indeed, in a meta-analysis of randomized controlled trials on using fiber supplements to reduce hypertension (and hopefully the incidence of cardiovascular disease), the average fiber supplement dose across 24 different studies was 11.5 grams of fiber supplement per day (17).

Some studies used lower doses, while others used a higher doses. Notably, the results of this same meta-analysis suggested that this dosage was an effective way to reduce blood pressure, so it provides strong evidence that doses around ten grams of fiber per day are a good place to start if you want to reap the long-term health benefits of fiber supplementation.

Double-check the fiber content of your supplement to get the dosing right. One important thing to note is that these dosages refer specifically to the fiber dosage, not the overall amount of powder. Fiber supplements are not 100% fiber by weight, so make sure you check the nutrition label to get accurate dosing information.

Fiber benefits FAQ

Q:Can fiber help with weight loss?

A: Yes, there’s good evidence that fiber helps with weight loss. It’s an effective appetite suppressant, meaning that it stimulates your body’s satiety response, indicating that you’ve gotten your fill of food and making you less inclined to eat more.

People who eat more fiber are less likely to overeat and gain weight, and moreover, fiber is an excellent way to fight some of the biggest negative health effects of being overweight: the increased risk for cardiovascular disease and the increased risk for type two diabetes (18).

While they aren’t the most high-tech supplement for weight loss, they are effective and have an excellent safety profile. If your diet isn’t already high in fiber, you should definitely add a fiber supplement if you are looking to lose weight.

Q: Can fiber help with diarrhea?

A: Dietary fiber is a popular way to “consolidate” stool, because it provides bulk in your digestive tract. A lot of research has been focused on using supplemental fiber to improve diarrhea in people in hospitals, and much of it supports the use of fiber for this purpose (19).

Fiber helps restore healthy populations of gut bacteria, which in turn improves the mucous lining of the intestines. Both of these changes are favorable from the perspective of reducing diarrhea, though it’s important to address whatever underlying cause (dietary or otherwise) that is resulting in diarrhea.

Q: What foods are highest in fiber?

A: When it comes to fiber, healthy foods are almost exclusively rich in fiber: leafy greens like broccoli, artichokes, spinach, and kale are all excellent sources of fiber, as are legumes (i.e. beans and lentils) as well as nuts like almonds.

As healthy as these foods are, most people on a Western diet don’t get enough of them to fulfil their dietary fiber needs. In fact, the average American gets less than half the recommended amount of fiber per day.

Q: What does fiber do in the body?

A: Fiber plays a critical role in your digestive tract. First off, it provides bulk, meaning it helps your body maintain regular and healthy bowel movements.

These are why fiber supplements are useful for both constipation and diarrhea. The bulking effects of fiber also generate a feeling of satiety, which is why fiber acts as an appetite suppressant. 

Q: Can fiber act as a probiotic?

A: Yes, one of the main benefits of fiber supplements is that they help probiotic bacteria in your gut flourish.

Even though the action of fiber is confined to your digestive tract, the fact that probiotic bacteria affect everything from your neurotransmitters to your systemic inflammation highlights the important role that fiber can play in regulating your overall health.

This also explains why fiber has such powerful effects on reducing your risk of developing chronic conditions like type two diabetes and heart disease.

Q: What fruits are high in fiber?

A: Most staple fruits have fairly high fiber content: bananas, apples, oranges, and strawberries are all fairly high in fiber, and raspberries and blueberries are particularly notable for their fiber content.

Tropical fruits like mangoes are also known for being rich in fiber. Both fruits and vegetables are beneficial beyond their fiber content; they have potent antioxidants that are known to reduce the risk for chronic diseases like heart conditions and cancer.

Related: Our best fiber picks


If you’re like most people, chances are you don’t get enough fiber in your diet. That means you’re missing out on key benefits for gut health, weight loss, blood sugar control, and more.

A fiber supplement is a great way to gain these benefits, even if you don’t always get fiber-rich foods like fruits and vegetables in your diet.

Taken at a dose of around 10-15 grams per day, a fiber supplement is great on its own, or as an addition to a shake, smoothie, or green drink.


John Davis

John Davis is a Minneapolis-based health and fitness writer with over 7 years of experience researching the science of high performance athletics, long-term health, nutrition, and wellness. As a trained scientist, he digs deep into the medical, nutritional, and epidemiological literature to uncover the keys to healthy living through better nutrition.