Types of fibre and their health benefits
Fibre. We know it as the part of our daily food intake that our body can't digest, and that passes along our digestive system helping to prevent constipation. Yet research over the last 20 years has shown an increasing number of different plant substances that influence our bowel health and function.
As well as the traditional 'roughage' fibre (also known as 'insoluble fibre'), we've now added 'soluble fibres' and 'resistant starches' to substances we know have an effect on bowel health.
Insoluble fibre is the type of fibre that can't be digested. It's naturally found in the outer bran layers of wholegrains. Wholegrains, such as wholemeal flour, wholemeal bread, brown rice and wholegrain pasta, are rich in insoluble fibre. This type of fibre adds 'bulk' to waste products, helping to keep you regular and avoid constipation.
Soluble fibres can't be fully digested by us, but can be used by our bowel bacteria as their food source. The 'gel' type nature of soluble fibres helps to regulate movement of food along the digestive tract. One benefit of this effect is a more sustained release of sugar from the digestion of dietary carbohydrates. This sustained release leads to better regulation of blood sugar control and also seems to offset hunger, too. Soluble fibres can also help lower blood cholesterol levels, especially the less healthy LDL cholesterol.
Foods rich in soluble fibre include oats, beans, fruits and vegetables. It's also possible to buy soluble fibres as tasteless powder added to drinks to boost fibre intake.
Food and fibre
Most nutrition experts suggest you get fibre from whole foods, because they're healthy in other ways, too. But if you don't get enough from your diet, there are ways to help fill in the gap. Evidence shows that most of us aren't getting enough. On average, most people in the UK get about 14g of fibre a day. The recent report from SACN, the UK's Special Advisory Group on Nutrition, recommends at least 30g a day.
Aim to eat a wide variety of different types of fibre. The following chart shows the most common types of dietary fibre, the main food sources for each fibre, and how that fibre helps maintain our health. It's also possible to buy fibre food supplements that can be added to foods and liquids to boost fibre content. These purified fibres are termed 'functional fibres' - such as wheat dextrins, versions of inulin and cellulose - and can be added to foods and drinks to boost daily fibre intake.
Insoluble (roughage) style fibres:
name of fibre
potential health benefits
Cellulose, some hemicellulose
Naturally found in wholewheat and whole grain flours, breads and products. Bran, seeds, nuts, brown rice, skins of produce.
'Nature's laxative': Reduces constipation by adding bulk to poo. Reduces risk of diverticulitis.
Found naturally in flax, rye, some vegetables.
Good for heart health and possibly immune function.