What is fibre in food?
Dietary fibre is mostly made up of the indigestible parts of plants, which pass relatively unchanged through our digestive system (stomach and intestines). Fibre is essential to keep the digestive system healthy. Food such as fish, meat and dairy products do not contain any fibre.
Different types of fibre in food
There are two different types of fibre: soluble and insoluble. Each type of fibre helps your body in different ways, so a healthy diet should include both types.
Soluble fibre can be digested by your body. It includes pectins, gums and mucilage, which is found mainly in plant cells and is found in some vegetables, fruit and legumes such as dried beans and peas. One of its major roles is to lower LDL (bad) cholesterol levels. Soluble fibre can help slow the digestion of food.
Insoluble fibre cannot be digested by your body. It includes cellulose, hemicelluloses and lignin, which make up the structural parts of plant cell walls. It passes through your digestive system without being broken down and assists other food to move more easily through your digestive system. It keeps your bowels healthy and helps prevent digestive problems. One of its major roles is to add bulk to faeces in order to prevent constipation and associated problems such as haemorrhoids.
Both types of fibre are beneficial to the body and most plant foods contain a mixture of both types.
Why is fibre in your diet good for you?
A diet high in fibre keeps the digestive system healthy. The digestive system is lined with muscles that massage food along the tract from the moment a mouthful is swallowed until the waste is passed out of the bowel. As fibre is relatively indigestible, it adds bulk to the faeces.
Soluble fibre soaks up water like a sponge, which assists to bulk up the faeces and allows it to pass through the gut more easily. It acts to slow down the rate of digestion. Insoluble fibre on the other hand overrides the slowing down effect, as it does not absorb water and speeds up the time that food passes through the gut.
To obtain the full benefits from a high fibre diet, it is essential to drink enough water every day.
A diet low in fibre can contribute to many disorders, such as constipation, haemorroids, irritable bowel syndrome, diverticulitis (small hernias of the digestive tract), obesity, diabetes and coronary heart disease.
Sources of fibre
Some of the best sources of soluble fibre include –
- Oats, barley and rye
- Fruit and dried fruit, if fresh fruit is not available
- Root vegetables such as potatoes (including the skin) and carrots
- Dried beans and peas
- Oats products
Good sources of insoluble fibre include –
- Wholewheat bread
- Bran and bran based cereals
- Nuts and seeds
In general, some good sources for a high fibre diet include –
- Beans (all beans), chickpeas and lentils
- Wholegrain and whole wheat bread and pasta.
- Brown or wholegrain rice
- Nuts, especially almonds, pecans and walnuts
- Jacket potato
- Fruit, even dried fruit, if fresh fruit is not available
- Bran based cereals
- Oats based products.
- Vegetables.
