Dietary fibre

by | Diet and Weightloss

What is fibre?

Dietary fibre is a component of plant materials. It is mainly made up of particular types of carbohydrate that are not digested by enzymes produced in the small intestine, but are largely broken down by bacteria in the large intestine.

Sources of dietary fibre include wholegrains such as rolled oats, barley, brown rice, cracked wheat and wholemeal or wholegrain breads; legumes (such as lentils, chick peas, kidney and other beans); nuts; seeds; fruits and vegetables. Some types of dietary fibre are described as ‘pre-biotics’ because of their role in increasing the quantity of healthy (‘good’) bacteria in the large intestine. Animal foods such as meat, fish, eggs, milk, yoghurt and cheese do not contain dietary fibre, although some varieties of yoghurt may have added fibre from a substance called inulin.

Benefits of fibre

A diet that’s high in dietary fibre is good for your health. High-fibre diets can help:

  • prevent and relieve bowel problems such as constipation, haemorrhoids, diverticular disease, and some cases of irritable bowel syndrome;
  • reduce cholesterol levels in the blood and thus reduce your risk of heart disease;
  • reduce your risk of type 2 diabetes; and
  • reduce your risk of developing certain types of cancer, especially bowel cancer.

Fibre and weight loss

Eating foods that are high in dietary fibre may also help if you’re trying to lose weight. That’s because high-fibre foods take longer to chew, are generally digested more slowly and make you feel fuller for longer. Many high fibre foods are also less energy-dense than other foods, meaning that they contain fewer kilojoules for the same amount of food and this may help a person reduce their overall kilojoule intake. Dietary fibre contributes 8 kJ/gram compared with 17 kJ/gram for other types of carbohydrate.

Insoluble fibre

Insoluble fibre – called so because it doesn’t dissolve in water – is the best type of fibre for relieving constipation because it increases stool volume, as well as the movement of material through your digestive system. Insoluble fibre is sometimes referred to as roughage or bulk. Good sources of insoluble fibre include whole-wheat flour, wheat bran, certain vegetables, and nuts.

Soluble fibre

Soluble fibre combines with water to form a gel-like material, and can help slow down the absorption of sugar. Soluble fibre is the best type of fibre for improving cholesterol and blood sugar levels. It is found in foods such as oats, lentils, citrus fruit, barley and beans.

Recommended fibre intakes

According to the Nutrient Reference Values for Australia and New Zealand (developed by the National Health and Medical Research Council (NHMRC) and the Department of Health), people need to eat the following amounts of fibre daily:

Recommended fibre intakes per day
Group Daily intake
Adult women at least 25 grams
Men at least 30 grams
Pregnant women over age of 18 28 grams
Breastfeeding women 27-30 grams

The NHMRC has also stated that increasing fibre intake even further — up to 38 grams per day for men and 28 grams per day for women — may reduce the risk of developing chronic disease (such as cardiovascular disease and diabetes). And if you get this added fibre by adding extra legumes, fruit and vegies to your diet, you will also increase your intake of antioxidant vitamins and folate, further improving the health benefits.

Unfortunately, some Australians don’t get the daily fibre they need, and many people are unsure which foods can help boost their daily dose of fibre.

Increasing your fibre intake

Here are some tips for increasing your fibre intake:

  • Try changing from white bread to whole-grain or multi-grain bread.
  • Substitute white rice and pasta with brown rice and whole-wheat pasta.
  • Eat a breakfast cereal that contains lots of oats or bran.
  • Try to fit in at least 5 serves of vegies and 2 serves of fruit every day.
  • Add beans or lentils to a casserole.
  • Instead of chips or chocolate, eat a handful of nuts for a healthy snack.

The amount of soluble and insoluble fibre varies in different foods, so it’s best to eat a wide variety of high-fibre foods. And while it’s possible to increase your fibre intake with fibre supplements, these supplements don’t contain the vitamins, minerals and other nutrients that are found in foods.

When you are buying packaged foods, it’s important to remember that not all foods that are labelled as ‘high in fibre’ actually contain a lot of fibre. It’s safest to read the food label to check just how many grams of fibre they contain.

Also, if you are planning on increasing the amount of fibre you eat, it may be wise to increase it slowly to reduce bloating and gas. Try adding in the additional fibre over a period of a couple of weeks. And remember to drink plenty of fluids too — this helps the fibre pass through your system.

Fibre content of different foods

Take a look at our table to find out the approximate fibre content of some different foods.

Fibre content of different foods
Food Total fibre in grams (g)
Bread, Burgen rye, 1 slice 3.0 g
Bread, whole-wheat, 1 slice 1.9 g
Bread, multi-grain, 1 slice 1.8 g
Bread, raisin, 1 slice 1.1 g
Bread, soy & linseed, 1 slice 3.5 g
Bread, white, commercial, 1 slice 0.9 g
Breakfast cereals
All Bran, 45 g — 1 serve 13.3 g
All Bran muesli, 45g; 1 serve 6.1 g
Sultana Bran, 45 g 6.74 g
Just Right Original, 40 g — 1 serve 3.8 g
Rolled oats or quick oats, 50 g raw – 1 serve 4.7 g
Weet Bix, 2 biscuits 3.3 g
Cornflakes, 35 g 1.8 g
Rice Bubbles, 35 g 0.9 g
Pear (medium), with skin 5.1 g
Mango, 1 medium 2.5 g
Apple (medium), with skin 3.5 g
Orange (medium) 3.5 g
Banana (medium) 2.9 g
Strawberries, 1/3 punnet 2.1 g
Green peas, frozen, 3/4 cup 8.8 g
Potato (medium), baked, boiled or steamed, skin on 4.6 g
Sweet corn, off cob, 1 ear 6.4 g
Beans, green, 1 cup 3.8 g
Sweet corn, canned, 110 g 3.0 g
Potato, peeled and cooked, 1 average 3.6 g
Carrot – 1 medium 4.1 g
Tomato, raw, 1 medium 1.8 g
Nuts and seeds
Pistachio, 30 g 2.7 g
Almonds, 30 g 2.7 g
Brazil, 30 g 2.6 g
Peanuts, 30 g 2.5 g
Walnut, 30 g 1.9 g
Cashew, 30 g 1.8 g
Pepitas (pumpkin seeds), 30 g 3.1 g
Chia seeds, 20 g 6.7 g
Lentils, 1 cup cooked 10 g
Baked beans, tinned, 1 cup 13 g
Red kidney beans, cooked, 1 cup 15 g
Muesli bar, fruit, 35 g 2.0 g
Popcorn, air-popped, 3 cups 3.6 g
Mars bar, 36 g 0.5 g
Potato chips, plain, 30 g 1.0 g
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