Question

What role does fiber play in digestion and absorption? Discuss how these can be attributed to health benefits and give examples. Be specific, support your answer and be sure to cite your sources using APA style.

Answer 1

Fibres are the complex carbohydrate substances found in plants, which do not completely breakdown by digestive enzymes. There are two types of fibres they are (i) Soluble fibres (ii) Insoluble fibres.

Soluble fibres – These fibres dissolve in water, and forms a gel like substance in digestive tract and slows down digestion. They are easily fermented in colon to gases and physiologically active by-products that is short chain fatty acids produced in the gut by colon bacteria, it is also called prebiotic fibre which delays the gastric emptying, and it gives a fullness of stomach.

Insoluble fibres:- These are the fibres which do not dissolve in water, and digestive enzymes of upper gastrointestinal tract do not digest them. These fibres bulk the substances, absorb water and helps in easing the excretion of solid waste material from the body.

Fibres does three important functions in digestive system they are (i) Bulking of excretory material (ii) Gives viscosity to food (iii) Helps in fermentation of food.

Bulking:- Cellulose and wheat bran gives good bulking effect, they absorb water increase the weight of the excretory material and causes regularity of passing the excretory material. Most of the bulking fibres are not fermented or fermented vey less in the GI tract.

Viscosity:- Viscous fibres thicken the contents of the intestinal tract, decrease the absorption of sugar and reduce the sugar response after eating, reduce lipid absorption, some viscous fibres like beta-glucan and pectin are partially fermented in intestinal tract, and some viscous fibres like psyllium are not fermented or very less fermented.

Fermentation:- Fermentable fibres are consumed by bacteria in large intestine, they slightly increase the weight of excretory material and produce short chain fatty-acid as by-product, resistant starch, inulin are fully fermented fibres. They contain soluble as well as insoluble fibres. The fermentation helps in expression of many genes in large intestine which affects the digestive function and helps in lipid and glucose metabolism, also helps in development of immune system.

Effect of fibre intake leading to health benefits:-

Dietary fibres change the nature of the substances of GI tract, some soluble fibres bind to bile acids in small intestine and do not allow them to re-enter body. It helps in lowering cholesterol level in blood, because the reduced or enteric loss of bile acids, helps the synthesis of more bile acids from cholesterol and as a result it reduces the cholesterol of body.

Dietary fibres reduce the risk of diabetes. Eating high fibre diet lowers the absorption of glucose from small intestine to blood, this reduces the need for insulin, the hormone required to control blood sugar level and as a result diabetes remains in control.

Fermentable fibres do not inhibit the absorption of minerals and vitamins, rather they improve the absorption, some fermentable fibres helps in absorption of minerals like calcium.

Dietary fibre helps in energy intake control and reduce risk of developing obesity. The viscosity producing effect of certain fibres help in giving a filling effect to body in intestine phase resulting modified GI tract function and delay the fat absorption. So fibres add more bulk and weight to the diet.

It lowers the LDL cholesterol reducing the risk of cardiovascular diseases. Fibres balances intestinal pH helping the intestinal fermentation process.

Fibre is important in the diet of aged people, as with age the digestive system slows down, it helps the digestive system.

Dietary fibres, cereal fibres and whole grain protect against colorectal cancer, as the bulk of excretory material increases it reduces the risk of colorectal cancer.

They also help in easing some irritable bowel syndromes.

The prebiotics the essential fibres helps in growing of the probiotics or the good bacteria which help in digestion in intestine.