Fiber supplements suffer a bit from a bad reputation. You probably consider fiber treatment for constipation and not much else. And yet, fiber can have a profound impact on your general health. Some evidence even suggests that it may reduce your risk of death from any cause.

One study followed 1,300 men throughout their later life and found that for every recent increase of 10 grams of fiber, heart disease deaths declined by 17%, while death from any cause declined by 9%. The association weakened with age but still showed fiber to offer a significant protective effect against death over your lifetime.

Other research has shown similar results for both men and women. Individuals with the highest fiber consumption, compared to those with the lowest, reduced the risk of death from all causes by 37%. Based on these results, it wouldn’t be unreasonable to conclude that fiber, in general, appears to protect your overall health.

What is Fiber?

Let’s look carefully at fiber and how it supports your health. Generally, people view fiber as “roughage.” Most fiber contains indigestible carbohydrates (with the notable exception of lignin) that pass through the small intestine intact.

Fiber types are usually divided into soluble and insoluble varieties. Insoluble fiber acts primarily as a bulking agent with a laxative effect, whereas soluble fiber acts as a food source for the bacteria in the large intestine. In addition, soluble fibers differ in their ability to gel or thicken. This gelling action may also contribute to some of the benefits seen with soluble fiber.

Examples of insoluble fiber include lignin (found in flaxseed and whole grains), cellulose, and some hemicellulose. Examples of soluble fibers include pectingumsinulinbeta-glucans, and resistant starch.

How Much Fiber is Enough?

General recommendations for fiber intake for adults under age 50 include 25 g for women and 38 g for men. In adults over 50 years old, recommendations get reduced to 30 g for men and 21 grams for women. These recommendations are based on targets derived from the research for lowering heart disease risk.

Many countries around the world do not meet this basic intake. Studies in the United States, France, and Brazil show that most people come up short and would benefit from increased fiber consumption.

Health Benefits of Fiber

1. Gastrointestinal Benefits of Fiber

When most people think of fiber, they think of gastrointestinal benefits. And the latest research does show that fiber supports gastrointestinal health. Studies have found a lower incidence of peptic ulcers, gallbladder disease, hemorrhoids, constipation, and diverticulitis with higher fiber consumption.

While people associate fiber with treating constipation, the research is actually somewhat mixed. Part of the problem is likely in the diversity of fibers that have been studied since different fiber types have varied effects. Insoluble fiber has a more consistent laxative effect and adds bulk to stools.

To increase insoluble fiber, fruits, vegetables, beansnuts, and whole grains are typical sources. While soluble fiber might help with constipation as well, you have to use the right type. Soluble fibers that form gels with high water holding capacity can soften stools effectively. Intact psyllium husk (not powdered) is an example. Soluble fibers that dissolve in water completely will not likely help with constipation.

Irritable bowel syndrome is a common digestive condition that is not well understood. The simplest treatments that can help typically involve the use of soluble fiber. A recent review of all the meta-analyses of fiber as a treatment for irritable bowel syndrome concluded that soluble fiber is beneficial for reducing symptoms.

Soluble fibers commonly used for irritable bowel include psyllium and flaxseed. While these fibers can be beneficial, in a subset of patients with irritable bowel syndrome, overgrowth of bacteria in the small intestine may cause an increase of symptoms with certain types of soluble fiber. Being aware of your response to any treatment, regardless of what the research says, is always important for your own health.

2. Fiber and Heart Disease

You might initially be surprised to learn that fiber has a protective effect on your heart. However, you’ve probably seen the labels on food, touting the heart benefits of fiber. The data remains so strong that the FDA allows for health claims on food items containing beta-glucans (found in oats) or psyllium fiber. Research has shown that fiber has several effects that likely benefit heart health, including:

  • Supporting healthy cholesterol levels
  • Balancing blood pressure
  • Potentially reducing inflammation

Fiber can help limit cholesterol by binding it up and carrying it out of the body. For blood pressure, it’s not exactly clear how fiber helps. The strongest data suggests that psyllium is the most effective at reducing blood pressure, although results are modest with a 2.4 point reduction in systolic blood pressure with added psyllium.

Soluble fiber also helps increase the levels of beneficial bacteria throughout the gastrointestinal tract. It acts as a food source for good bacteria. These bacteria produce anti-inflammatory short-chain fatty acids from fiber that appear to help reduce levels of inflammation. Fiber also helps control blood sugar. By regulating elevated blood sugar — which is linked to increased inflammation — fiber helps to lower your overall risk.

3. Fiber and Type 2 Diabetes

Some of the same mechanisms that show benefits in heart disease also have benefits for diabetes. It really shouldn’t be too surprising, since diabetes carries an increased risk for heart disease and the two conditions have overlapping underlying risk factors.

Fiber slows the absorption of carbohydrates, helping maintain a more stable blood sugar level. Over time, this can translate into better insulin control in diabetes. Lower blood sugar and insulin can help slow the progression of the illness, mitigating some of the more devastating long-term outcomes of the condition. A small trial in people with diabetes involved consuming a high fiber diet composed of 25 grams of soluble and 25 grams of insoluble fiber daily. Blood sugar was better controlled with the high fiber diet and improvements in cholesterol and triglycerides were also evident.

And the benefits transcend just the treatment of diabetes. Increased fiber intake has also been shown to help prevent the disease as well. For every two grams of cereal fiber, research has shown a 6% reduction in diabetes risk. Insoluble and fruit fiber also appeared to help in most of the published studies. Interestingly, vegetable and soluble fiber were not found to be effective for decreasing risks of diabetes, although these findings might be somewhat misleading since total fiber intake was still associated with preventative benefits.

4. Fiber and Weight Loss

Unfortunately, there are a lot of dubious claims and products marketed for weight loss. However, some types of fiber appear to provide at least modest benefits. The most recent meta-analysis on fiber for weight loss found that an average dose of 16 g of soluble fiber per day over approximately ten weeks reduced weight by 5.5 pounds. However, the authors suggest caution in interpreting the results since they did see large variations among the published studies.

Glucomannan is a soluble fiber derived from konjac roots. It expands in the digestive tract increasing a sense of fullness which potentially helps reduce food intake. Overall, research on glucomannan for weight loss remains somewhat mixed. However, higher doses of a specific glucomannan product, PGX, may have more consistent benefits for decreasing weight.

Additional studies are needed to evaluate glucomannan fully. The supplement also comes with some potential gastrointestinal side effects. Keep in mind that you need to take glucomannan, like all fiber supplements, with plenty of water to ensure safety.


Fiber offers more than just a treatment for constipation. Fiber has significant potential to help prevent a number of conditions, including heart disease, diabetes, and gastrointestinal illnesses. The data strongly suggests that fiber protects from “all-cause mortality,” decreasing your risks of death from any cause.

If you know you lack enough fiber in your diet, adding a fiber supplement could be a way to make sure you capture all the benefits from adequate fiber intake.


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