What is Fiber ?

Dietary fiber is a plant-based nutrient that is sometimes called roughage or bulk. It is a type of carbohydrate but, unlike other carbs, it cannot be broken down into digestible sugar molecules. Therefore, fiber passes through the intestinal tract relatively intact. However, on its journey, fiber does a lot of work.

The term “dietary fiber” refers to the indigestible parts of plant-based foods. In other contexts, “fiber” might refer to plant-based cloth, but when speaking of nutrition, the terms “fiber” and “dietary fiber” are often interchangeable.

About Fiber 

Dietary fibre helps keep the gut healthy and is important in helping to reduce the risk of diseases such as diabetes, coronary heart disease and bowel cancer. Fibre reaches the large bowel undigested where it is fermented by bacteria. The by-products of this fermentation are carbon dioxide, methane, hydrogen and short-chain fatty acids (SCFAs). The SCFAs are used by the body. Initially, increasing fibre intake can cause an increase in gas production which can result in bloating. However, depending on the type of fibre chosen, our bodies do adapt and gas production for most people should decrease over time. Soluble fibre and resistant starch also function as prebiotics and support the probiotics (bacteria) we have in our large bowel which are essential for digestive health.


“Dietary fiber aids in improving digestion by increasing stool bulk and regularity,” said Smathers. This is probably fiber’s best-known benefit. Bulkier, softer stools are easier to pass than hard or watery ones, which not only makes life more comfortable, but also helps maintain colorectal health. According to the Mayo Clinic, a high-fiber diet may help reduce the risk of hemorrhoids and diverticulitis (small, painful pouches on the colon).

Heart health

Fiber also helps lower cholesterol, said Kelly Toups, a registered dietitian with the Whole Grains Council. The digestive process requires bile acids, which are made partly with cholesterol. As your digestion improves, the liver pulls cholesterol from the blood to create more bile acid, thereby reducing the amount of LDL (bad) cholesterol.

Blood sugar regulation

A meta-analysis of studies regarding the relationship between fiber and blood glucose (blood sugar) levels published in The Journal of the American Board of Family Medicine found that increased fiber intake can reduce blood glucose levels during the standard fasting blood glucose test (a test of blood sugar levels after an overnight fast).

The article showed that levels of HbA1c also decreased with increased fiber. HbA1c refers to glycated haemoglobin, which occurs when proteins in the blood mix with blood sugar. It is associated with increased risk of diabetes complications.     Soluble fiber is especially helpful in this regard.

Possible cancer prevention

The research has been mixed regarding the link between fiber and colorectal cancer prevention. While the National Cancer Institute asserts that a high-fiber diet does not reduce the risk to a clinically significant degree, a 2011 meta-analysis from the British Journal of Medicine found an association between cereal fiber and whole grain intake and reduced risk of colorectal cancer.

A more recent animal study suggested that fiber might only cause this benefit if a person possesses the right kind and amount of gut bacteria. Fiber naturally reacts with bacteria in the lower colon and can sometimes ferment into a chemical called butyrate, which may cause cancer cells to self-destruct. Some people naturally have more butyrate-producing bacteria than others, and a high-fiber diet can help encourage the bacteria’s growth.


According to some scientists, fiber could actually help people live longer. A meta-analysis of relevant studies published in the American Journal of Epidemiology concluded, “high dietary fiber intake may reduce the risk of total mortality.”

One recent study suggests that cereal fiber, from foods like whole-grain bread, cereal and pasta, is especially effective. Over a 14-year period, those who ate the most cereal fiber were 19 percent less likely to die than those who ate the least.

Food allergies and asthma

New research suggests that fiber could play a role in preventing food allergies, the existence of which has long puzzled scientists. Again, this theory comes down to the interaction between fiber and bacteria in the gut.

Scientists theorize that people are not producing the right gut bacteria to tackle foods commonly associated with allergies, like peanuts and shellfish. Without the right bacteria, particles of these foods can enter the bloodstream via the gut. Fiber helps produce a bacterium called Clostridia, which helps keep the gut secure.

The same reasoning explains why fiber might help people with asthma. Unwanted particles escaping the gut and entering the bloodstream can cause an autoimmune response like asthmatic inflammation. A 2013 animal study found that mice eating a high-fiber diet were less likely to experience asthmatic inflammation than mice on a low- or average-fiber diet.

Deficiency symptoms of fibre

Poor Digestive Health

Diets low in fiber or high in fat increase the risk for constipation, diverticular disease and hemorrhoids. There are two types of fiber, insoluble and soluble, which are both beneficial and pass through the body without being digested. Insoluble fiber plays an integral role in keeping the intestines and colon functioning properly. It regulates bowel movements and may potentially reduce the risk of colon cancer as well. Along with plenty of water, insoluble fiber adds bulk to the stool, helping reduce constipation. Good sources of insoluble fiber are whole-wheat flour and wheat bran, most vegetables and nuts.

Cardiovascular Disease

Elevated levels of total and LDL cholesterol in the blood significantly increase the risk of arterial diseases, such as coronary heart disease and stroke. Lifestyle habits including consuming a low-fiber diet contribute to these higher cholesterol panels. Soluble fiber, found in foods such as citrus fruits, pears, beans and oats, binds with the bad LDL cholesterol in the intestinal tract and helps rid the body of it. The Academy of Nutrition and Dietetics recommends consuming 7 to 13 grams of soluble fiber daily, as part of the total fiber consumed, to reduce LDL. Increased fiber intake has also been found to help reduce high blood pressure.

Weight Gain

When the diet consistently lacks high-fiber foods, weight gain is a risk. Fiber helps increase satiety, and without it people often overeat. High-fiber foods generally require more chewing time and are digested slower than refined carbohydrates or sugars, so they can help keep the stomach feeling full longer. Substituting a 1.5-ounce bag of potato chips for 1.5 ounces of whole-wheat pretzels plus one small apple adds almost 7 grams of fiber to the daily diet for the same number of calories.

Poor Blood Sugar Control

Low-fiber, refined carbohydrates, such as white bread and sugary foods, get digested quickly in the body, leading to a quicker rise in blood sugar. Soluble fiber can slow absorption of sugar that is consumed at the same time. This causes blood sugar levels in the body to remain more stable. Research shows that dietary fiber in foods may actually reduce the risk of Type 2 diabetes.

Ways to Increase Fiber

It is unclear whether or not fiber supplements offer the same benefits as high-fiber foods, since foods contain many other beneficial nutrients not contained in the supplement. To limit the risk of many health problems, include a variety of plant-based high-fiber foods in your diet daily. Experiment with more vegetarian recipes, try new fruits and choose whole-wheat breads or brown rice instead of the white versions whenever possible.