Why is dietary fibre an important part of a balanced diet?

Dietary fibre (also called roughage) is the indigestible portion of plant foods, primarily made up of cellulose and other complex carbohydrates that human digestive enzymes cannot break down. Its importance in a balanced diet lies in its role in regulating digestion and preventing constipation.

Fibre works by absorbing water in the large intestine, which adds bulk to the stool and makes it softer and easier to pass. This stimulates peristalsis - the wave-like muscular contractions that move food through the digestive tract - promoting regular bowel movements and reducing the risk of constipation, haemorrhoids, and diverticular disease.

The other options misattribute functions to fibre:

• Providing a high source of calories is incorrect because fibre is largely indigestible and contributes minimal caloric energy.
• Being a source of essential amino acids is wrong because amino acids come from proteins, not fibre.
• Helping the body absorb vitamins more quickly is not a recognised function of dietary fibre. Fat-soluble vitamins require dietary fat for absorption, not fibre.