Dietary fibers are the complex polysaccharides that are not usually digested by the human digestive system. They usually don’t provide any nutrition as they are not acted upon by the digestive enzymes but give many more benefits. It is also known as roughage and is only obtained from the plant foods. They usually absorb water and promote the easy bowel movement. Usually, they are beneficial in constipation. They primarily consist of celluloses, hemi-celluloses, lignins, pectins and gums. They are usually non-starch polysaccharides. They have major health effects on the circulatory system and heart that is the vital organ for a person to live. In this article, the discussion will be about the nature, importance, functions and benefits of dietary fibers in human life and body.
Types of fibers:
There are usually two types of dietary fibers. These include:
Soluble dietary fiber
Insoluble dietary fiber
The description of these is given below:
Soluble dietary fiber:
Soluble fibers are those types of fibers that are partially soluble in fibers. These fibers are fermented in the colon and the intestinal tract into gases and other products such as short chain fatty acids by the gut bacteria that are the probiotics mainly Bifidobacteria known as the useful microflora of the human gut. They usually delays the gastric emptying time and when absorbs water produces bulk and creates the feeling or sensation of fullness.
Sources of soluble fibers:
These fibers are present in variable quantities in plant foods. Some sources of soluble fibers are given below:
Legumes (peas, soybeans, lentils and other beans)
Oats, rye, and barley
some fruits (including figs, avocados, plums, prunes, berries, ripe bananas, and the skin of apples and pears)
Certain vegetables such as broccoli, carrots, and raddish etc
Root tubers and root vegetables such as sweet potatoes and onions (in their skins there is high fiber content)
Seed husks (a mucilage soluble fiber) and the wheat bran
Nuts and almonds that are the highest in dietary fiber
Some important functions of soluble dietary fibers:
They form gel in the intestinal tract and slow down the gastric emptying time.
They also slow down the passage of food.
They contribute to satiety.
They decrease the glucose absorption and reduce the plasma cholestrol level.
They also give relief to the diabetics and hypertensive patients when its appropriate proportion is present in diet.
Some types of soluble fibers:
Some types of the soluble fiber include the following:
They are present in many fruits e.g guava, apple and in roots of turnips. Water soluble pectins and proto-pectins are found in the plant cell wall and middle lamella.
Pectin forms a stiff gel in the presence of sucrose and citric acid and is important in the formation of jellies.
Plant cell wall is also cemented by the pectins and protopectins.
Like other fibers they are not digested by the human digestive system but assists in the passage of digestible materials and other wastes through the intestine.
They are acted upon by bacteria in the intestine and produce gases like carbon dioxide and many other products such as alcohols and organic acids that have an anti-cancer effect.
Gums and mucilages:
They are usually polysaccharides with alternating monomer unit structures of several sugars. They are usually present in plants and grain cereals. Some gums include:
Oat and barley gums
Like other dietary fibers, gums and mucilages pass through the gastrointestinal tract undigested but posses some important physiological benefits.
There are many names of agar that are agar agar, macassar gums and vegetable gelatin. They are dried and purified stems of seaweed.
It is partially soluble and swells with water to form a gel.
It is used in soups, jellies, ice-creams, meat and fish pastes etc.
Insoluble dietary fibers:
These fibers are insoluble in water but have many health benefits on the human digestive tract. They include:
whole grain foods
wheat and corn bran
legumes such as beans and peas
nuts and seeds
Some important functions of insoluble fibers are given below:
They absorb large amount of water while passing through the digestive system that increases the fecal bulk.
They accelerate the transit time, slow starch hydrolysis and delay glucose absorption.
This fraction is also equally beneficial for diabetic patients.
So, dietary fibers must be included in your diet as they strengthen the digestive system that is the main system upon which our health resides.