Why is eating fibre important?
13th Jan 2023 Food Heroes
Fibre is not actually a nutrient, since it is never absorbed by your body, but it is a valuable component of your diet. Here's why it's so important
What is fibre?
Fibre, simply put, is the stuff in plants that your body can’t digest. It’s the husks on the grains and the stringy threads in celery. Fibre performs some vital functions in the body. There are two basic types of fibre: insoluble (insoluble in water) and soluble.
Insoluble fibre, which used to be known as roughage, helps move waste through the digestive tract by producing a bulkier, softer stool that stimulates the muscle movements of the bowel. Some good sources of insoluble fibre are wheat bran and whole grains, the skins of apples and pears, and vegetables such as potatoes, carrots and broccoli.
"Fibre, simply put, is the stuff in plants that your body can’t digest"
Soluble fibre is a gel-like substance that helps to thicken the stool. It may be broken down by gut bacteria to form beneficial substances. Soluble fibre is found in oats, barley, beans and many fruits and vegetables.
Different countries have different daily targets for fibre consumption, varying from 25g to 38g, but health experts agree it’s a good idea generally to aim for about 30g per day.
Benefits of fibre
A high-fibre diet helps to prevent constipation, creating a soft stool that is easy to pass and moves through the gut more quickly. This may help to reduce the risk of colon cancer, as any toxins or carcinogens are diluted and spend less time in the bowel.
Fibre encourages the normal growth of the bowel cells too. Fibre feeds the beneficial bacteria that are naturally in the colon, discouraging harmful germs from growing there. The "good" bacteria can break down the fibre to make butyrate, a short-chain fatty acid that acts as a gut tonic, providing energy to the bowel cells and helping to keep them healthy.
"A high-fibre diet helps to prevent constipation"
Fibre is also bulky and absorbs water so it fills you up fast. It also slows down digestion, prolonging feelings of fullness, which can help in maintaining a healthy weight.
Soluble fibre (such as that found in beans and lentils) has been shown to help to reduce cholesterol in your blood, protecting your heart. It also helps to keep blood glucose levels steady.
In addition to the known benefits of fibre itself, foods that are naturally high in fibre (foods from plant sources) tend to be rich in other important nutrients.
Fibre and the glycaemic index
The glycaemic index (GI) is a ranking of carbohydrate foods according to their effect on blood glucose levels. The theory is that the faster a food is broken down during digestion, the quicker the rise in blood glucose levels.
High-fibre foods tend to take longer to eat, and the fibre stops the food from being quickly digested. Both of these factors help to reduce the glycaemic index (GI), so high-fibre foods tend to have a lower GI than their low-fibre equivalents.
"High-fibre foods tend to take longer to eat, and the fibre stops the food from being quickly digested"
Another concept is the glycaemic load (GL) which takes into account both the quality of carbohydrate (its GI) and the quantity in food. A food’s GL is the amount of carbohydrate in one serving, multiplied by the GI divided by 100. This represents an "adjusted" value for the food’s carbohydrate content. Although the GL is useful in scientific research, it is hard to apply to everyday food choices if serving sizes vary, so GI is a more helpful guide to choosing what to eat.
Read more: What is the history of Marmite?
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