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Fibre

Fibre has always been synonymous with ‘being regular’ but it is also protective against bowel disorders and heart disease. Fibre is a type of carbohydrate, however, unlike other carbohydrates, our bodies are not able to break fibre down into simple sugars. Therefore fibre does not provide us with energy and passes through our small intestine undigested. Foods rich in fibre also contain powerful protective agents, such as antioxidants and phytochemicals. High fibre diets can also help in weight control and the management of diseases such as diabetes.

What does fibre do?

Fibre is only found in plant products, but in two forms – soluble and insoluble.

Soluble fibre acts like a sponge, absorbing fluid and making the bowel contents softer and able to move more easily. It also helps lower blood cholesterol and improves blood glucose control.

Insoluble fibre acts as a ‘bulking agent’ which, with soluble fibre, helps to keep us regular. This effect is useful in the treatment of conditions such as constipation, diverticular disease and hemorrhoids.

High-fibre foods are bulky and filling, so eating them at each meal helps with regulating appetite and weight management.

Some types of fibre are prebiotic, which means they act as food for the good bacteria in our gut. While humans can’t digest (breakdown) fibre, these bacteria can. These good bacteria help our bodies with several processes including blood sugar control, immune function, and even brain function. Eating a wide range of plant foods provides us with different types of fibre which supports a thriving good bacteria in our gut to thrive.

Which foods contain fibre?

Foods rich in soluble and insoluble fibre are listed below.

Soluble

  • Oats
  • Legumes – dried peas, beans, lentils
  • Vegetables – especially broccoli, Brussels sprouts, carrots, potato, kumara
  • Fruit – especially apples, pears, citrus, stone and berry fruit

Insoluble

  • Bread – mixed grain, wholemeal
  • Wholegrain cereals
  • Wholewheat pasta
  • Rice, especially brown rice
  • Corn, cornmeal, polenta
  • Fruit & Vegetables

Note that fibre is increasingly being added to many processed foods e.g. breakfast bars. However, we should aim to get most of our fibre from whole foods.

How much fibre do we need?

Most New Zealander’s don’t eat enough fibre. Many of us eat less than half of the recommended amount of 25g for women and 30g for men each day. Tips for increasing your fibre intake are listed below. Adding high-fibre foods to your diet should be done gradually, to minimise possible side effects such as wind and bloating. High-fibre diets are not recommended for young (preschool) children. High fibre foods are too filling, preventing young children from eating enough to meet their vitamin and mineral needs.

Fibre content of a range of foods

Food itemFibre (g)
1 cup frozen mixed vegetables8.6
½ cup baked beans8.2
½ cup stewed apricots7
½ cup muesli6.5
1 bran muffin
6
2 Weetbix4.8
1 cup brown rice3.7
1 slice wholemeal bread3.2
1 kūmara2.8
Dried apricots (10 halves)2.7
1 slice wholegrain bread2.6
2 slices white high-fibre2.6
1 cup porridge2.1
1 apple or banana2
2 slices white bread1.6

Tips for eating more fibre

  • Aim for at least 5 servings of vegetables and at least 2 servings of fruit each day. Leave the skin on, as it contains much of the fibre. Fruit and vegetable juices contain little or no fibre.
  • Choose wholegrain varieties of bread, cereals, rice and pasta. When baking, try substituting half of the white flour with wholemeal flour.
  • High-fibre breakfast options include porridge or muesli. Increase the fibre further by adding oat bran or wheat germ, nuts, seeds (sunflower, sesame, pumpkin) and fruit (fresh, canned)
  • Try adding chickpeas, kidney beans or lentils to soups, casseroles.
  • If you are eating more fibre-rich foods, drink more water than usual as fibre absorbs water in the body.

Can you eat too much fibre?

While most people don’t eat enough, there are some times when too much fibre may be the issue

  • Irritable Bowel Syndrome: If you experience diarrhoea symptoms, then eating too much insoluble fibre can make symptoms worse.
  • Increasing your fibre intake too fast: This can lead to symptoms such as excessive bloating and gas (because the fibre in your body is broken down by the good bacteria, which generate gas). Increase your fibre intake slowly so that your body can adjust and drink more water as you go.

If you are experiencing ongoing gut issues we recommend working with a dietitian who can assess the root cause and find the correct fibre recommendation for you.

Note that the Nutrient Reference Value for Australia and NZ have not set an upper limit for fibre as, due to the filling nature of the fibre, it’s pretty hard to over-consume.

NZNF White Paper – Dietary Fibre

Click to read our paper on Dietary Fibre

This paper reviewed the current evidence of health benefits associated with dietary fibre. Starch, simple sugars and non-polysaccharides are all components of dietary fibre and are responsible for bulking faecal matter, increasing viscosity, transit time and Short Chain Fatty Acids production.  It is reasonable to conclude that the beneficial effects of dietary fibre include a reduction in the risk of obesity, type-2 diabetes and coronary heart disease. It is also probable that adequate dietary fibre, particularly from grains, reduces the risk of colorectal cancer. These associations for chronic diseases have been found to have an inverse relationship with dietary fibre intake, with higher amounts being more protective.

Last modified: March 11, 2022