How Much Fibre Do You Need Per Day?

Fibre is the most under-eaten nutrient in Australia and the one with the broadest payoff. It feeds your gut bacteria, slows glucose absorption, lowers cholesterol, and makes meals genuinely more filling. Most adults here eat noticeably less than the recommended amount, and the gap is almost entirely explained by refined grains replacing whole ones.

This guide covers how much you need, where to get it, and — the part that usually gets skipped — how to increase it without spending a fortnight bloated.

How much fibre do you need per day?

Australia's NHMRC Nutrient Reference Values set two different figures, and the distinction is worth understanding:

The Adequate Intake is what a normal healthy population consumes and does fine on. The Suggested Dietary Target is the higher intake associated with reduced chronic disease risk. If you're aiming at long-term health rather than just adequacy, the SDT is the number worth chasing.

Soluble and insoluble fibre do different jobs

You don't need to track them separately, but knowing the difference explains why one high-fibre change fixes constipation and another fixes cholesterol.

• Soluble fibre dissolves into a gel. It slows digestion, blunts glucose spikes and binds cholesterol. Found in oats, barley, psyllium, legumes, apples, pears and citrus.
• Insoluble fibre doesn't dissolve. It adds bulk and speeds transit — the one that resolves constipation. Found in wheat bran, wholegrain breads and cereals, nuts, and the skins of most vegetables.
• Resistant starch behaves like fibre and is the preferred fuel of several beneficial gut species. Found in cooked-and-cooled potato and rice, slightly green bananas, and legumes.

A varied whole-food diet delivers all three without any accounting. That variety is itself the goal — see gut health for why the number of different plants you eat matters as much as the total grams.

High-fibre foods, by the numbers

Legumes dominate that list, and that's the practical takeaway: one cup of beans or lentils covers roughly half a day's target on its own. A tin of chickpeas in a curry does more for your fibre intake than a week of switching snacks.

How to increase fibre without the bloating

This is where most attempts fail. Someone reads that they need 38 g, goes from 18 g to 38 g on a Monday, feels awful by Wednesday, and concludes fibre doesn't agree with them. It almost always does — the increase was just too fast for the gut microbiome to adapt.

1. Add roughly 5 g per week, not 20 g overnight. Your gut bacteria need one to two weeks to shift population in response.
2. Increase water alongside it. Fibre without adequate fluid makes constipation worse, not better — this is the most common self-inflicted problem.
3. Spread it across meals rather than one enormous high-fibre dinner.
4. Start with soluble sources (oats, psyllium, peeled fruit) if you're sensitive; wheat bran is the harshest starting point.
5. Rinse tinned legumes well and introduce them in quarter-cup portions.

Do you need a fibre supplement?

Food first, for a straightforward reason: whole foods bring fibre packaged with vitamins, minerals and polyphenols, and a supplement brings fibre alone. That said, psyllium husk is genuinely useful and well evidenced — particularly for cholesterol and for regularity — and it's a reasonable bridge while you rebuild intake from food. Treat it as a supplement to a good diet, not a substitute for one.

Where to start

Pick the two highest-leverage swaps rather than overhauling everything: switch your bread and breakfast cereal to genuinely wholegrain versions (check the label for fibre per 100 g, not the word "wholemeal" on the front), and add a legume to one meal a day. That combination alone typically moves people from the low twenties into the thirties.

Fibre also does a lot of the work in managing blood glucose — if that's your reason for being here, read the insulin resistance diet guide next.