I know in the US you all spell fiber like this ‘fiber’ but here in AUS we spell it as ‘fibre’, I know it’s like this in the UK too. So I haven’t spelt everything wrong it’s just the way we spell it here 🙂
What is Dietary Fiber?
Dietary fibre comes from a variety of foods of plant origin such as grains, legumes, fruits and vegetables. The dietary fibre component forms the structure of all these plants. If you imagine the ‘fibrousness’ of plants then you can get a clear picture of the fibre component, right? Dietary fibres are refered to as non-starch polysaccharides and what sets them apart is their resistance to digestive enzymes in the small intestine, much of the fibre passes through the small intestine to fermentation, digestion, and utilisation in the large intestine. Non-starch polysaccharides include cellulose, hemicellulose, pectins, gums and mucilages.
Types of dietary fibre and their roles
There are predominantly two types of dietary fibre, soluble and insoluble, with the exception of a few starches known as resistant starches.
Soluble fibre has the ability to dissolve, attracting water and digestive juices and forming vicious gels such as pectins, gums and mucilages. These pectins, gums and mucilages act to slow down emptying of the stomach and slow down food transit into the gastrointestinal tract. This slows absorption of nutrients including glucose/sugars. A good example of soluble fibre is fruit. Though it contains fructose/sugar, the large amount of soluble fibre fruit contains slows down the absorption of the sugars, aiding blood glucose from spiking too heavily and keeping insulin in check. Soluble fibre is also fermented by bacteria in the large intestine, with numerous beneficial health effects. Common sources of soluble fibre include oats, fruit, beans and legumes.
Insoluble fibre is known as cellulose and hemicellulose and is found in foods such as whole grains and vegetables. The insoluble fibre does not dissolve in water like soluble fibre but provides roughage, volume and bulk that helps preventing constipation and keep the digestive tract healthy. It also helps form a lattice work in the intestines to slow down nutrient absorption.
Resistant starch is still starch but the structure is enclosed rendering it resistant to digestion, with only a small component available for digestion in the small intestine. Resistant starch acts like dietary fibre and is actively fermented by gut bacteria into components that the body can re-utilise.
How much dietary fibre do we need?
The recommended intake is 30g/day for males, 25g/day for females.
Most people do not get enough fibre with estimates stating men only get around 23.8g/day, while women are only getting 18.9g/day. The average overall is around 20g a day, which is 5-10g below recommendations.
Overview of the benefits of dietary fibre
The largest human immune organ is the gastrointestinal tract, also know as your digestive tract. Dietary fibre can help maintain the health of your digestive tract and this provides positive influence over many health factors.
- reduce cholesterol
- assist weight management
- prevent diabetes
- prevent heart disease
- prevent constipation
- prevent digestive infections
- prevent haemorrhoids
- prevent appendicitis
- prevent diverticula
- prevent colon cancer
I hope that explains what dietary fiber/fibre is and why you need to eat more vegetables 🙂
Nutrition & Health Coach