You have probably heard that whole plant and whole grain foods are good for the health, but do you know exactly how and why?

Dietary fiber is the major reason for this. It is a carbohydrate which is part of the plant which is indigestible, and which travels through the digestive system and absorbs the water as it goes to promote bowel movements.

But there has been growing evidence that apart from aiding your digestion, fiber can be essential for the reduction of the risk of developing chronic disease, reduce your risk of heart disease, diabetes, as well as help you lose weight as well due to its effect on the gut flora microbiota.

Read on to find out what the different types of dietary fiber are, and what the scientific evidence for their benefits is.

What exactly is dietary fiber?

Dietary fiber is the part of your diet which is not actually digested by the enzymes in our GI tracts, but this non-digestible carb still plays a vital role for your digestive system and for your overall health.

Dietary fiber is usually found in vegetables, whole grains, fruits and legumes, and its intake on a regular basis is known to reduce the risk of developing diabetes and heart disease.

There are two main types of fiber:

Another way to distinguish the two types of fiber is – fermentable and non-fermentable.

Understanding the difference between the two types is key because while some type of fiber has essential health benefits for the health, others are not so important.

But distinguishing the two is not so easy because there are insoluble fibers which can be digested, and there are foods which have both soluble and insoluble fibers but are richer in one type more than the other.

The daily recommended amount of fiber intake is 25g for women and 38g for men, and after the age of 50 – 21g for women and 30g for men. Preferably, the daily servings of fiber should be divided in at least five servings of fruit or vegetables, and one or more servings of whole-grain products.

Oatmeal, beans, Brussels sprouts, oranges, nuts, blueberries, and apples are rich in soluble fiber. Insoluble fiber is found in the skins and the seeds of fruits, as well as in brown rice and whole-wheat bread.

Oats, flaxseeds, and oat brans are rich in both types of fiber.

Foods like dairy and white bread have little or no fiber.

Related: Learn more about foods with soluble fiber

Fiber can help feed the beneficial gut bacteria

It may come as a shock to some, but bacteria which live in the human body usually outnumber the body’s cells by 10 times.

We have bacteria residing on our skin, in the nose, mouth, and elsewhere, but the majority live in the gut, mostly in the large intestine.

There are over 500 different species of bacteria residing in the intestine, totaling around 100 trillion cells. These bacteria and other microorganisms are referred to as gut flora or microbiome.

This isn’t something you should be alarmed about. In fact, the bacteria in the gut are essential for our digestive system and for the overall functionality and health of the body.

Some of the bacteria are especially vital for blood sugar control, body weight control, brain function, metabolism and immune function.

Now let’s bring in the fiber. The bacteria in the large intestine are no different from any other organism or microbe in that they require food to survive and thrive.

But by the time the food reaches the large intestine, most of the carbohydrates, fats, and proteins have been absorbed, leaving the bacteria there with little to feast on.

These bacteria are able to digest fiber, but humans do not, thus they feast on the fibers that make it to the intestines.

Certain fibers serve as prebiotics, feeding the good bacteria already present in the colon, and are thus crucial to human health and welfare.

Short-chain fatty acids like butyrate, acetate, and propionate are produced by beneficial bacteria and are essential to human health.

These short-chain fatty acids feed the cells in the colon and thus reduce the risk of inflammation of the gut, as well as improve certain digestive problems like irritable bowel syndrome, ulcerative colitis and Crohn’s disease.

As the bacteria ferment the fibers, they produce gases, which is the reason why some people experience flatulence or stomach discomfort when eating high fiber diets.

These side effects will usually disappear as the body gets used to consuming and digesting higher quantities of fiber.

Certain types of fiber promote weight loss

Fiber has been found to promote weight loss, and adding just 30g of fiber to your diet per day can help you reduce your weight, lower your blood pressure and improve your response to insulin.

The soluble fibers which can absorb the water in the intestine can help slow down the absorption of nutrients by the digestive tract, and can also promote the feeling of fullness for a longer time.  This will reduce hunger, and can reduce appetite.

Also, soluble fiber helps block the digestion and absorption of some of the fat, by spreading out around it as a thick gel.

Some studies show that an increase in fiber in the diet can automatically lead to a decrease in calorie intake.

But the resulting weight loss results largely depend on the type of fiber introduced to the diet.

Some soluble fibers have a much more significant effect on weight loss as compared to others.

One of the soluble dietary fibers with the highest water absorption ability is the popular glucomannan found in shirataki noodles and in the dietary supplement Lipozene. This natural fiber has the ability to absorb 50 times as much water as its size.

See also: Glucomannan Supplement – Is It Effective for Weight Loss?

Other health benefits of consuming dietary fiber

It can help stabilize blood sugar levels

Just like it slows down the absorption of fat, soluble fiber also slows down the digestion of the other nutrients in our food including carbohydrates.

This means that eating soluble fibers along with carbohydrates can prevent the sudden spikes in blood sugar levels which can occur after the consumption of high carb foods and meals.

High fiber foods do have lower glycemic indexes than refined carbs which have had most of their fiber removed.

According to studies, high viscosity water-soluble fibers are able to stabilize blood sugar levels and prevent blood sugar spikes.

If you’re eating a lot of carbohydrates and want to avoid potentially fatal spikes in blood sugar, this is crucial.

If you struggle with high or fluctuating blood sugar levels, reducing your intake of carbohydrates (especially simple, low-fiber carbs like sugar and white bread) and increasing your intake of soluble fiber may help.

The amount of insulin required to maintain healthy blood sugar levels in diabetics has been shown to decrease in trials where higher fiber intake was a factor.

Plus, fiber can help slow down the absorption of sugar into the bloodstream and introduce it slowly to prevent spikes in its levels too.

It can help lower cholesterol and reduce the risk of heart disease

Soluble fiber can help prevent some of the dietary cholesterol from being broken down and digested, and after regular intake, the fiber can help reduce the free cholesterol in the blood.

A review including 67 different studies has found that the consumption of 2-10g of soluble fiber on a daily basis leads to the reduction of cholesterol by 1.7mg/dl and of the “bad” LDL cholesterol by 2.2mg/dl.

According to research, the consumption of soluble fiber can lead to the reduction of cholesterol levels and can thus help protect against heart disease.

This correlation to depends on the viscosity of the soluble fiber.

Overall, scientists who took part in various studies agree that an increase in the intake of fiber can reduce cholesterol levels.

It can help resolve constipation

This is one of the most common reasons why people resort to high fiber diets – resolving constipation problems.

As it moves through the digestive tract, fiber absorbs water and thus helps increase the bulk of the stool. This also helps speed up its movement through the intestine.

Another study found the opposite – that people with constipation who were placed on high fiber diets saw no improvement while those on lower fiber diets reported that their bowel movements had improved.

Once again, the result depends on the type of fiber consumed.

The fiber which increases the content of water in the stool has a laxative effect while the fiber which adds more dryness to the dry stool has a constipating effect.

But in general, insoluble fiber does help add to the bulk and to the faster movement of the stool through the bowel and prevents constipation, slow bowel movements, and possible gastrointestinal blockage.

In addition to protecting against colorectal cancer, it can also prevent hemorrhoids and folds in the colon.

Water is absorbed by some soluble fibers, turning them into a gel-like material in the digestive system. They aid digestion and are safe from fermentation by gut microbes.

Sorbitol and similar substances have a laxative effect because they absorb water in the colon.

Overall, it is clear that certain types of fibers can help constipation while others can worsen it, so it is essential that you take the right type of fiber for your specific problem.

It can help reduce the risk of colorectal cancer

Colorectal cancer is the third leading cause of death by cancer worldwide.

There are numerous studies which have found a correlation between the high intake of fibers and a reduced risk of this type of cancer.

However, many high-fiber meals, such as fruits, vegetables, and whole grains, also include antioxidants and other healthful nutrients that may have an effect on cancer risk.

Therefore, isolating the effect of fiber on reducing the risk of colorectal cancer from the many other potential benefits of a healthy whole-food diet is impossible.

The link between high-fiber diets and reduced cancer risk has not yet been conclusively established.

But while there is no firm evidence, it is clear from the other studies, that eating a healthy high-fiber diet with whole grains, fruits and veggies can play an important role for cancer prevention.

It helps feed the healthy bacteria in the gut

Fiber reaches the lower intestine undigested, and it provides the food which the good bacteria in the gut need to get fuel to properly absorb the nutrients and to keep the body healthy. It acts like a natural prebiotic.

Healthy gut flora is essential for a proper digestive system, as well as for the immune system, for fighting inflammations in the gastrointestinal tract, and even for brain health.

So, dietary fiber is essential for keeping a well-balanced microbiome, and for encouraging the growth of good bacteria in the gut.

See also: What is Kombucha and which are its benefits

Final words

Dietary fiber, soluble or insoluble, has a number of health benefits. It is, in fact, an essential nutrient for all humans, even though we don’t have the enzymes to digest and absorb it.

Dietary fiber helps feed the beneficial gut bacteria. It forms short-chain fatty acids which help nourish the wall of the colon.

Plus, it can help slow down the digestion and absorption of other nutrients like carbohydrates, proteins, and fats, and thus prevent blood sugar spikes.

It also gives a feeling of fullness and helps prevent the pangs of hunger for longer periods of time after eating. And it can slow down and limit the absorption of fat, and other high-calorie nutrients.

It can also help reduce the cholesterol levels and thus decrease the risk of stroke, heart attack and other heart and cardiovascular problems.

It is beneficial for diabetics, and people suffering from high blood sugar, and insulin resistance.

And it can help resolve problems like constipation, and according to some findings may even reduce the risk of developing colorectal cancer.


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