How Much Fibre Do You Need a Day? Why It Matters and How to Get More

Written by Robbie Clark, BExSc (Nutrition), M (Nutr+Diet), Accredited Practising Dietitian (APD) and Exercise Scientist · Last updated 16 October 2026 · 7 references

Most of us know fibre is good for us, but fewer people know what it actually does or whether they're eating enough. Here's how much you need, why it matters and simple ways to get more, plus what to know before you try a supplement.

What is fibre?

Fibre is the part of plant foods that your body can't digest. Instead of being absorbed in the small intestine, it travels to the large intestine, where some types are fermented by your gut bacteria and others add bulk to your stools.

You'll find it in vegetables, fruit, legumes, nuts, seeds and wholegrains. Some breads, cereals, drinks and yoghurts also have fibre added.

How much fibre do you need a day?

The NHMRC sets these Adequate Intakes of fibre a day:⁶

• Children 1–3 years: 14 g
• Children 4–8 years: 18 g
• Boys 9–13 years: 24 g; girls 9–13 years: 20 g
• Boys 14–18 years: 28 g; girls 14–18 years: 22 g
• Men 19 years and over: 30 g; women 19 years and over: 25 g
• Pregnancy: 25 g (14–18 years) or 28 g (19 years and over)
• Breastfeeding: 27 g (14–18 years) or 30 g (19 years and over)

To help reduce the risk of chronic disease, the suggested target for adults is higher: 38 g a day for men and 28 g a day for women.⁷

Why does fibre matter?

People who eat the most fibre have a 15–30% lower risk of heart disease, stroke, type 2 diabetes and bowel cancer than people who eat the least. The benefits were greatest at about 25–29 g a day, and higher intakes may help further. Most of this evidence comes from observational studies, but trials also show that eating more fibre lowers body weight, blood pressure and cholesterol.¹

Fibre also matters for your bowel. Higher fibre intake is linked with a lower risk of diverticular disease, where small pouches form in the bowel wall and can become inflamed. Each extra 10 g of fibre a day was linked with about a 26% lower risk.²

How does fibre help your body?

• It keeps you regular. Fibre adds bulk and holds water, making stools softer and easier to pass.
• It feeds your gut bacteria. When bacteria ferment fibre, they produce short-chain fatty acids, which fuel the cells lining your bowel.
• It can help you feel full. High-fibre foods take longer to eat and digest. Thick, gel-forming (viscous) fibres, found in oats, barley, legumes and psyllium, are the type linked with small weight benefits in trials.⁵
• It slows the rise in blood glucose after meals, especially from soluble fibre.

How can you get more fibre?

Try one swap a day for a week:

• Monday: add a small handful of mixed nuts to your yoghurt
• Tuesday: blend a tablespoon of LSA (ground linseed, sunflower seeds and almonds) into your smoothie
• Wednesday: serve your stir-fry with brown rice instead of white
• Thursday: add a can of rinsed kidney beans or chickpeas to a salad or soup
• Friday: top your breakfast cereal with berries
• Saturday: choose wholegrain bread instead of white
• Sunday: add an extra cup of vegetables, such as broccoli, to your evening meal

Increase your fibre gradually over a few weeks and drink plenty of water. Adding a lot at once can cause wind, bloating, cramps or diarrhoea.

Do fibre supplements work?

Food is the best source of fibre, because fibre-rich foods also provide vitamins, minerals and other nutrients that supplements don't. But a supplement can help in some situations:

• Constipation. Fibre supplements improve stool frequency and consistency in people with chronic constipation. Psyllium works best, especially at more than 10 g a day taken for at least four weeks.³
• IBS. Soluble fibre such as psyllium (also called ispaghula) is a recommended first step for IBS. Insoluble fibre such as wheat bran isn't, as it can make symptoms worse.⁴
• Weight. Viscous fibre supplements led to a small extra weight loss of about 0.8 kg in people following a reduced-energy diet. They aren't a weight-loss solution on their own.⁵

Common types of fibre supplement include psyllium husk, methylcellulose, partially hydrolysed guar gum, inulin and wheat dextrin. Whichever you choose, start with a small dose, increase slowly and take it with plenty of water.

Frequently asked questions

How much fibre should I eat a day?

Adult women need about 25 g a day and men about 30 g, with higher targets of 28 g and 38 g to help lower chronic disease risk.^6,7

What happens if I eat too much fibre too quickly?

You may get wind, bloating, cramps or diarrhoea. Increase slowly over a few weeks and drink plenty of water.

Is psyllium good for IBS?

Soluble fibre such as psyllium is a recommended first step for IBS; wheat bran isn't, as it can make symptoms worse.⁴

Can fibre help you lose weight?

High-fibre diets are linked with lower body weight, but fibre supplements on their own make only a small difference.^1,5

Are fibre supplements safe to take every day?

For most people, yes, but check with your practitioner or pharmacist if you take medicines or have diabetes.

References

Research (PubMed)

1. Reynolds A, Mann J, Cummings J, et al. Carbohydrate quality and human health: a series of systematic reviews and meta-analyses. Lancet. 2019;393(10170):434–445. PubMed 30638909
2. Aune D, Sen A, Norat T, et al. Dietary fibre intake and the risk of diverticular disease: a systematic review and meta-analysis of prospective studies. Eur J Nutr. 2020;59:421–432. PubMed 31037341
3. van der Schoot A, Drysdale C, Whelan K, Dimidi E. The effect of fiber supplementation on chronic constipation in adults: an updated systematic review and meta-analysis of randomized controlled trials. Am J Clin Nutr. 2022;116(4). PubMed 35816465
4. Vasant DH, Paine PA, Black CJ, et al. British Society of Gastroenterology guidelines on the management of irritable bowel syndrome. Gut. 2021;70(7):1214–1240. PubMed 33903147
5. Jovanovski E, Mazhar N, Komishon A, et al. Effect of viscous fiber supplementation on obesity indicators in individuals consuming calorie-restricted diets: a systematic review and meta-analysis of randomized controlled trials. Eur J Nutr. 2021;60:101–112. DOI 10.1007/s00394-020-02224-1

Australian guidelines

6. NHMRC. Nutrient Reference Values for Australia and New Zealand: dietary fibre. View source
7. Australian research reporting the NHMRC Suggested Dietary Target for fibre: Healthcare expenditure and productivity cost savings from reductions in cardiovascular disease and type 2 diabetes associated with increased intake of cereal fibre among Australian adults. Nutrients. 2018;10(1):34. View source

This article is general information, not medical advice. Speak with your practitioner about your own situation before changing your diet.