Fantastic Fibre

Summary

Fibre helps to keep our digestive system healthy and helps to keep us feeling fuller for longer. It is a type of carbohydrate that comes from plants.  There are three main types: soluble fibre which keeps us feeling full; insoluble fibre which helps us to poo more easily; and resistant starch which encourages “good” bacteria that can help us break down fibre to grow in our large intestine.

Most of us aren’t getting enough fibre. But don’t go overboard: too much, especially in someone very young, can cause diarrhoea and make them feel full too quickly. If they feel full, they may not eat enough food to give their body all the nutrients they need to stay healthy.

What is it?

Fibre is a type of carbohydrate (like sugars and starches) and comes in three main types: soluble, insoluble, and resistant starch. It’s in the parts of plants that we can’t break down (digest) by ourselves to release energy (calories) – like cellulose cell walls, woody tissues, seed husks, gums and pectins.

What do the different types of fibre do?

Although food labels generally lump them all together as “dietary fibre”, each has a slightly different effect in our bodies. It’s good to make sure we are getting some of each type.

• Soluble fibre dissolves in water in our body to become a gel-like substance that keeps us feeling full and slows down the emptying of our stomach. It also lowers cholesterol and blood sugar levels and supports the growth of helpful bacteria.
• Insoluble fibre mostly keeps its shape and absorbs water as it passes through our gut, softening the bowel contents. Provided we’ve drunk enough water, this eases and speeds up movement of food through our gut. It helps prevent constipation (trouble pooing), helps us feel full, and keeps our gut healthy.
• Resistant starch heads straight to the large intestine where it helps keep it healthy by promoting the growth of bacteria that partly breakdown fibre for us. (They are often called “good bacteria” in advertisements.)

Where do we get fibre from naturally?

Fibre is only found in plants. It may be added to processed or non-plant foods like yoghurts. Fruits, vegetables, grains, legumes, seeds and nuts are all great natural sources of fibre.

• Soluble fibre is found in pectins and gums and in good amounts, in fruits (especially citrus, apples and blueberries), vegetables, oats, barley, and legumes. Beta glucan is one common type, found in wholegrains, oats, barley and some mushrooms.
• Insoluble fibre comes from wholegrain breads, cereals, nuts, seeds, wheat bran, the skin of fruits, and vegetables like cauliflower, beans, carrots, potatoes.
• Resistant starch comes from heating then cooling some foods like undercooked pasta, rice, or potatoes. Under-ripe bananas and legumes are other great sources.

How does soluble fibre affect the levels of substances outside the gut?

By slowing down the rate at which food passes from our stomach into the small intestine soluble fibre reduces how much glucose we absorb from it into our bloodstream. Soluble fibre also binds to bile acids in the gut stopping us reabsorbing some of the cholesterol they contain, which helps to keep cholesterol levels down, and in turn to reduce heart disease.

How does the fibre content of some common foods compare?

The Ministry of Health recommends 20 g to 24 g fibre per day as an adequate amount for 9- to 13- year-old girls and boys and about 25 g to 30 g for adult women and men. Manufacturers use a DI (daily intake) value of 30 g fibre to calculate %DI values on packets.

Are we getting enough?

Most of us aren’t getting enough fibre. The average daily dietary intake for NZ adults is only 20 g. Although children need less, most are probably still not getting enough. But don’t go overboard: too much fibre, especially in someone very young, can cause diarrhoea, interfere with appetite and affect the absorption of other nutrients. Breakfast cereals with over 6 g fibre/100 g, preferably over 10 g, are great, but ones with over 15 g probably have too much fibre for small tummies.

Why do only some nutrition information panels (NIPs) list “dietary fibre”?

Manufacturers don’t have to list fibre on a NIP unless they’ve made a claim about its presence, level or health effects. There must be over 2 g/serve for it to be listed. The NIP values are total values and don’t distinguish between different types of fibre, unless the claim’s about a certain type. “Functional” fibre (substances like inulin, psyllium, dextrins added to boost fibre levels in some yoghurts, drinks or breakfast cereals) is also combined with other fibres in the total count.

What are three quick ways to increase the amount of fibre we eat?

– Try whole grain or wheatmeal breads, pastas and flours instead of white.
– Eat more seeds, nuts, fruit and veges – and keep their skins on.
– Add legumes or pulses like beans, lentils and chickpeas to stews, curries and salads.

It’s best to increase fibre gradually, because the bacteria which ferment it in our gut release gases which can make us feel bloated (and need to escape!) until the body adapts. And we need to make sure we also increase the amount we drink to soften up all that fibre so it can do its job properly.

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References

Colorado State University, November 2012. “Dietary Fiber”. Fact Sheet 9.333. Retrieved from: http://extension.colostate.edu/topic-areas/nutrition-food-safety-health/dietary-fiber-9-333/ 23 August 2017.
Ministry of Health, October 2015. “Eating and Activity Guidelines for New Zealand Adults”. Retrieved from: http://www.health.govt.nz/system/files/documents/publications/eating-activity-guidelines-for-new-zealand-adults-oct15_0.pdf 23 August 2017.
Ministry of Health, July 2012. “Food and Nutrition Guidelines for Healthy Children and Young People (Aged 2–18 years): a Background Paper. Partial Revision February 2015.” Retrieved from: http://www.health.govt.nz/system/files/documents/publications/food-nutrition-guidelines-healthy-children-young-people-background-paper-feb15-v2.pdf 23 August 2017.
National Health Service, UK, 22 September 2015. “How to Get More Fibre into Your Diet”.  Retrieved from: http://www.nhs.uk/Livewell/Goodfood/Pages/how-to-get-more-fibre-into-your-diet.aspx 23 August 2017.
Nestle, n.d. “Dietary Fibre Factsheet”. Retrieved from: https://www.nestle.co.nz/nhw/nutritionfactsheets/dietaryfibre 28 August 2017.
New Zealand Nutrition Foundation, n.d. “Fibre”. Retrieved from: https://www.nutritionfoundation.org.nz/nutrition-facts/Nutrients/carbohydrates/fibre 23 August 2017.

Useful links

Choice.com., 1 May 2015. “Breakfast Cereal Reviews” and Retrieved from: https://www.choice.com.au/food-and-drink/bread-cereal-and-grains/cereal-and-muesli/articles/breakfast-cereal-review    and https://www.choice.com.au/babies-and-kids/feeding-children/making-healthy-choices/articles/kids-breakfast-cereal-review  29 August 2017.