Fibre: Your hidden health weapon

There’s a lot more to fibre than keeping you regular, says Dietitian Caitlin Reid. It can lower blood cholesterol, help with weight-loss and reduce development of heart disease and bowel cancer. Here’s how to get more in your diet.

For most of us, fibre conjures up images of bran-filled cereal bowls, funny tasting liquids and an association with ‘keeping regular.’ But fibre is actually one of your body’s most powerful health tools, and it’s linked with everything from weight-loss and lower blood cholesterol to reducing your chance of developing obesity, heart disease, diabetes and even colon cancer.

Yet most of us just aren’t getting enough of it. Thanks to highly processed foods, busy lifestyles and our eat-and-run habits, the average Australian adult only consumes around 18–25g of fibre a day – when the adequate intake (AI) for adult males is 30g and 25g for females (see table below).

Incredibly, the suggested dietary target (SDT) to prevent disease is much higher. Fortunately, it’s easy to bump up your fibre intake – you just have to know how.

What is it?

Fibre is the part of plants that is resistant to digestion and absorption in the small intestine. When we eat plants or plant-based foods, some parts are broken down entirely and absorbed by the body, but fibre passes through the small intestine to the large intestine, where it is either completely or partially fermented.

You will find fibre in everything from corn and cashews to broccoli and baked beans. But additional fibre, such as Hi-Maize, is added to up the fibre in breads, breakfast cereals, drinks and yoghurts.

Types of fibre

Fibre is often broadly referred to as a singular food component, but there are actually three distinct kinds of fibre, with each one giving your body different health benefits.

Soluble fibre soaks up water like a sponge while being processed in the digestive tract. This helps to plump out the faeces and slows the rate of digestion, helping you feel fuller for longer and allowing your body to absorb more nutrients. There’s a whole host of health benefits associated with eating soluble fibre, but the most notable is reduced blood cholesterol levels. Good sources of soluble fibre include oats, legumes, seeds, fruit and vegetables.

Insoluble fibre is fermented in the bowel and makes waste material soft and bulky – which makes it easier to pass through the intestines quicker, helps with constipation and keeps us ‘regular’. Insoluble fibre is found in wholegrains, in cereals and in ‘tough’ foods, such as the skin of fruit and vegetables.

Resistant starch, although not traditionally known as a fibre, works in the same way, ‘resisting’ digestion and absorption in the small intestine until it reaches the bowel, where it ferments. You can find it in many starchy foods, like unprocessed cereals and grains, firm bananas, potatoes and lentils, and also added as Hi-Maize in some breads and cereals.

Fighting with fibre

It’s commonly recognised that fibre is essential for maintaining proper digestive function, but did you know that you can also prevent or impact on a range of other conditions just by getting the right amount in your diet? Research has found many links between fibre and better health, including:

Bowel cancer

When researchers at the National Cancer Institute in the US looked at the link between cancer and fibre consumption, they found those who increased their consumption of grain-based food reduced the risk of developing small bowel cancer by 49%, while those who ate more wholegrains reduced their risk by 41%. Similarly, a European Prospective Investigation of Cancer and Nutrition study of 400,000 people found a diet rich in fibre reduced their risk of bowel cancer risk by up to 40%.

Weight management

Fibre is your secret weapon in the weight-loss war: numerous studies have found that people who follow high-fibre diets weigh less and are less likely to gain weight compared to those who eat minimal fibre. High-fibre foods take longer to digest, have a lower energy density, generally take longer to chew and keep you feeling fuller for longer than foods with little fibre; all things that impact your daily kilojoule intake.

Diabetes

Soluble fibre slows down the rate at which your stomach empties, which reduces the post-meal rise in blood glucose levels. This is thought to help control blood sugar levels, and potentially helps prevent the development of type 2 diabetes.

Cardiovascular disease

As soluble fibre breaks down in the digestive tract, it forms a thick gel which helps trap substances that promote high cholesterol levels. In other words, adding soluble fibre to your diet means lower cholesterol levels – and a lower risk of heart disease.

Digestive health

Because fibre adds bulk, it helps create softer stools that are easier to pass; preventing or relieving constipation. But a high fibre intake can also help prevent the development of diverticulitis – the development, infection and possible rupture of small, bulging pouches of tissue that press outward from the bowel wall.

Although The National Health and Medical Research Council recommends the fibre intake amounts listed (see below) as adequate for general health, there are also additional recommendations for chronic disease prevention. These are called suggested dietary targets (SDT) and are higher than the adequate intakes shown. To help prevent chronic disease, the SDT to aim for are 38g/day for males and 28g/day for females.

What's an adequate intake (AI) of fibre?

A week’s worth of ways to boost your fibre

Monday: Add 30g mixed nuts to your reduced-fat yoghurt (total fibre: 2g).

Tuesday: Sneak 30g bran or LSA (linseed, sunflower seeds and almonds) into your smoothie (total fibre: 6g).

Wednesday: Serve your stir-fry with 1 cup brown rice instead of white rice (total fibre: 3g).

Thursday: Add a small tin of kidney beans or chickpeas to your salad (total fibre: 6g).

Friday: Add blueberries (100g) to your breakfast cereal (total fibre: 4g).

Saturday: Eat wholegrain bread instead of white bread (total fibre: 5g).

Sunday: Add 1 cup cooked broccoli to your evening meal (total fibre: 7g)