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.
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.
Foods rich in soluble and insoluble fibre are listed below. For good health, eat a mix of soluble and insoluble fibre.
Soluble fibre dissolves in water and forms a gel-like substance in your gut. This helps to soften your stool. Beta-glucans, a type of soluble fibre, can help reduce blood cholesterol levels.
Insoluble fibre does not dissolve in water. Rather it adds bulk to our stool, making it easier to pass.
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.
It is recommended that adults have:
Source: Nutrient Reference Values (NRV) | Dietary Fibre
However, to get more protection from chronic disease (in particular heart disease), it is recommended to follow the Suggested Dietary Target (SDT)
Source: NRV | SDTs
Most New Zealanders don’t eat enough fibre. Many of us eat less than half of the Adequate Intake 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.
Note, that very high-fibre diets are not recommended for young (preschool) children as the filling nature of fibre can prevent young children from eating enough to meet their energy, vitamin and mineral needs. The recommended amount of fibre for children and adolescents can be found on the NRV | Dietary Fibre webpage.
Most people don’t eat enough fibre. Furthermore, the NRVs for Australia and NZ have not set an upper limit for fibre as there is not enough evidence to set a specific limit. However, in some circumstances too much fibre may be an issue:
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.
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 reviewed: 18/07/2022
Last modified: August 16, 2023
