Almost everyone has heard that fibre is good for you. Far fewer people could say what it actually is, what it does once you’ve eaten it, or how much they should be getting. That gap in knowledge probably helps explain a much bigger one: UK government advice is for adults to eat 30g of fibre a day, yet the NHS says most of us average about 20g, and in the latest national diet survey only around 4% of adults reached the target.

This guide takes you from the basics through to the practical stuff. We’ll look at what fibre is and the different types, why it matters for your gut, heart and long-term health, how much you need at each age, and where it comes from. Then comes the part most people really want: how to raise your intake to the recommended level without ending up bloated and uncomfortable. Along the way you’ll find a fibre table for everyday foods, a seven-day vegetarian meal plan that reaches 30g, and a calculator to check your own day.

Everything here is general information rather than personal advice, and there’s a short section near the end on who should be careful.

Key takeaways

• Dietary fibre is the part of plant foods your body can’t digest. Most of it is fermented by gut bacteria in the large bowel.
• UK advice for adults is 30g a day. Most adults eat about 20g, and only a small minority reach 30g.
• Higher fibre intakes are linked to a lower risk of heart disease, stroke, type 2 diabetes and bowel cancer.
• The best sources are wholegrains, pulses, vegetables, fruit, nuts and seeds. Meat, fish, eggs and dairy contain none.
• Build up gradually over a few weeks and drink plenty of fluid to avoid wind, bloating and cramps.

What is dietary fibre?

Dietary fibre is the part of plant foods that your body can’t break down and absorb in the small intestine. Instead of being digested like sugar or starch, it carries on to the large intestine, where it is partly or completely fermented by the bacteria that live there, as the British Dietetic Association (BDA) explains.

That’s why fibre is found only in plant foods: wholegrains, pulses, vegetables, fruit, nuts and seeds. Meat, fish, eggs and dairy contain none. It’s also why preparation matters. Peeling fruit and vegetables or choosing refined flour removes fibre, because much of it sits in the skins, seeds and outer layers of the plant.

A quick note on numbers, because they confuse people. In 2015 the UK’s Scientific Advisory Committee on Nutrition (SACN) broadened the official definition of fibre and moved to a measurement method called AOAC, which is now used on UK food labels. Under the old method the advice was 18g a day, roughly equivalent to 24g on the new one, so the 30g target is about 6g more than the old advice rather than a different goal altogether. If you find an older leaflet quoting 18g, that’s why.

The different types of fibre

Fibre isn’t one substance. It’s a family of compounds with different jobs, and most plant foods contain several at once. The usual shorthand splits them into soluble fibre, which dissolves in water, and insoluble fibre, which doesn’t. Researchers accept that this isn’t a perfect system, but it’s a handy way to understand what’s going on, and a review in the Proceedings of the Nutrition Society lays out the main groups.

Type	What it does	Where you’ll find it
Insoluble fibre (cellulose, hemicellulose, lignin)	Adds bulk to stools and helps food move through the gut	Wholegrain bread and cereals, wheat bran, nuts, vegetables, and the skins of fruit and potatoes
Soluble fibre (pectins, beta-glucan, gums)	Forms a gel that slows digestion, helps lower cholesterol and softens the rise in blood sugar after meals	Oats and barley (beta-glucan), apples, citrus fruit and berries (pectin), beans, lentils, peas, chia and linseed
Resistant starch	Escapes digestion and is fermented in the large bowel	Pulses, slightly underripe bananas, and potatoes, pasta or rice that have been cooked and cooled
Prebiotic fibres (such as inulin)	Selectively feed some gut bacteria	Onions, garlic, leeks, bananas, oats and chicory root

In practice you don’t need to count each type. A diet built around a variety of plant foods delivers a mix automatically, and that’s what the evidence supports: SACN points out that most of the research comes from studies where fibre is a natural part of whole foods, so it advises getting your fibre from a variety of food sources rather than relying on one type, or on added fibre.

Why fibre matters for your health

The strongest evidence comes from a large 2019 analysis published in The Lancet, commissioned by the World Health Organization. It pooled studies from nearly 40 years and found that people with the highest fibre intakes had a 15 to 30% lower risk of death from any cause, death from cardiovascular disease, coronary heart disease, stroke, type 2 diabetes and bowel cancer than people with the lowest intakes. For every extra 8g of fibre eaten per day, risks fell by roughly 5 to 27% across several of those outcomes, and the benefits looked set to keep growing at higher intakes. These are observational findings, so they show an association rather than proof, but the certainty of evidence for fibre was graded as moderate.

Digestion and regularity

Fibre’s best-known job is keeping things moving. Insoluble fibre adds bulk to stools and speeds their passage, while soluble fibre holds water and softens them. The NHS notes that fibre-rich foods help digestion and prevent constipation, and diets rich in pulses and wholegrains seem particularly effective at shortening transit time.

Feeding your gut bacteria

Once fibre reaches the large bowel, resident bacteria ferment it into short-chain fatty acids such as butyrate, which provide energy for the cells lining the gut. Researchers think a varied fibre intake supports a more diverse gut microbiome, although how different fibres affect specific bacteria is still being worked out. If this is your interest, my post on protecting your gut microbiome covers the other side of the coin: the foods worth cutting back on.

Heart health and cholesterol

Soluble fibre reduces the reabsorption of bile acids in the small intestine, which in turn lowers circulating cholesterol. Oat beta-glucan is the best studied, with around 3g a day needed for an effect, which is roughly a bowl of porridge plus an oat-based snack. Reviews also link every extra 7g of total fibre a day to about 9% lower cardiovascular disease risk.

Blood sugar and type 2 diabetes

Soluble fibre thickens the contents of the gut, slowing the absorption of glucose and softening the spike after a meal. One review found type 2 diabetes risk was about 6% lower for every extra 7g of fibre a day, and wholegrains appear to be particularly protective.

Bowel cancer

The NHS lists a lower risk of bowel cancer among the associations of a fibre-rich diet. One proposed explanation is that fermentation in the colon, together with faster transit and more bulk, dilutes potential carcinogens. The mechanisms are still not completely understood, and fibre is one piece of a wider lifestyle picture rather than a guarantee.

Fullness and weight

Soluble fibre slows stomach emptying, and fibre-rich foods tend to be filling for their calories. In the clinical trials pooled in the Lancet analysis, higher fibre intakes were linked to lower body weight, blood pressure and total cholesterol. The effect on weight is modest, so think of fibre as a helpful ally rather than a weight-loss method.

How much fibre do you need?

For adults the UK recommendation is 30g of fibre a day, set by SACN in 2015 and repeated by the NHS. It’s the same for men and women, and it’s an average to aim for over time rather than a number to hit to the gram every day. Children need less, rising with age:

Age	Fibre per day
2 to 5 years	About 15g
5 to 11 years	About 20g
11 to 16 years	About 25g
16 to 18 years	About 30g
Adults	30g

Now the reality check. The NHS puts average adult intake at about 20g a day. In the most recent National Diet and Nutrition Survey (2019 to 2023), only around 4% of adults met the 30g target, according to the Food Foundation’s analysis. The government cautions that the survey method changed, so those results can’t be compared directly with older ones, which put the figure nearer 9%. Either way, the shortfall is large and widespread.

Is 30g a ceiling? Not necessarily. Dose-response analyses suggest benefits keep growing at higher intakes, and the lead author of the Lancet study has suggested aiming for at least 25 to 29g from food. The sensible target for most people is to reach 30g steadily and comfortably, then let it settle there.

It’s also a lot of plants. SACN’s own worked example reaches 30g with five portions of fruit and vegetables, two slices of wholemeal bread, a portion of high-fibre breakfast cereal and a baked potato, among other wholegrain choices, which is a long way from the typical British diet. Researchers have described the target as achievable but requiring substantial change in dietary habits.

Where does dietary fibre come from?

In the UK, roughly half of our fibre comes from cereal foods such as bread and breakfast cereals, and around a third from fruit and vegetables, with potatoes counting as a vegetable here. Pulses contribute relatively little, which is a pity because they’re among the most fibre-dense everyday foods. For a longer list of ideas, see my earlier post on fibre-rich foods.

Food group	Food	Typical portion	Fibre per portion
Wholegrains and starchy foods	Porridge oats	40g dry (a small bowl of porridge)	3g
	Wholewheat cereal biscuits (such as Weetabix)	2 biscuits	4g
	Wholemeal bread	1 slice (35g)	2.5g
	White bread	1 slice (35g)	0.5g
	Wholewheat pasta, cooked	150g	6g
	Jacket potato, skin on	1 large (200g)	5g
	Brown rice, cooked	150g	2g
	Oatcakes	2 (25g)	1.5g
Pulses	Baked beans	80g (about 4 tbsp)	3.5g
	Lentils, cooked	80g	6g
	Chickpeas, cooked	80g	4g
Vegetables	Peas	80g	3.5g
	Broccoli	80g	2g
	Carrots	80g	2.5g
	Sweetcorn	80g	2g
	Tomatoes	80g (1 medium)	1g
Fruit	Apple	1 medium	2g
	Banana	1 medium	2g
	Raspberries	80g	2.5g
	Avocado	Half (75g)	2.5g
Nuts and seeds	Almonds	30g (a small handful)	3.5g
	Chia seeds	1 tbsp (12g)	4g
	Peanut butter	1 tbsp (15g)	1g

Some patterns jump out. Pulses, seeds and nuts pack the most fibre into a small portion. Wholemeal bread gives around 2.5g a slice against about 0.5g for white. And leaving the skin on a jacket potato turns it into one of the best-value fibre sources on the plate. Treat the numbers as a guide: for packaged foods, the nutrition label beats any table, including this one.

How to increase your fibre intake to 30g a day

Closing a gap of around 10g sounds daunting, but it’s mostly a matter of small swaps repeated daily. Here’s how I’d approach it.

1. Find your starting point

Run through a typical day with the calculator further down this page. Most adults land near 20g, so you’re looking for roughly 10g more, which is about two or three of the swaps below.

2. Go slowly

Jumping from 20g to 30g overnight is the classic route to wind, bloating and cramps. One NHS hospital leaflet suggests introducing high-fibre foods gradually over two to three weeks. If you feel uncomfortable, hold at your current level for a few days before stepping up again.

3. Drink enough fluid

Fibre draws water into the bowel, so as your intake rises you need enough fluid for it to do its job, otherwise it can make constipation worse. The same leaflet suggests around 1.5 to 2 litres of fluid a day, mostly water or diluted squash.

4. Swap, don’t just add

The easiest gains come from replacing refined foods with wholegrain ones. Choose porridge or wholewheat cereal biscuits at breakfast, wholemeal or granary bread, wholewheat pasta and brown rice, and potatoes with the skins on. Switching a sandwich from white to wholemeal bread adds about 4g across two slices.

5. Give pulses a regular slot

Beans, lentils and chickpeas are the heavy hitters. A single 80g portion adds around 3.5 to 6g. Tinned versions are cheap and count just as well, so stir them into curries, soups, stews, pasta sauces and salads.

6. Eat the whole thing

Keep the skins on potatoes, apples and pears, choose whole fruit over juice, and add vegetables to every meal. For snacks, think fruit, vegetable sticks, oatcakes, and unsalted nuts and seeds, as the NHS suggests.

7. Read the label

Under UK rules a food can claim to be a “source of fibre” if it has at least 3g per 100g, and “high in fibre” at 6g or more per 100g. Check the per-100g column and the serving size, because a high-fibre cereal eaten in a tiny portion delivers less than the claim suggests.

8. Be wary of added-fibre shortcuts

Fibre-boosted drinks, bars and snacks are everywhere, often using ingredients such as inulin or chicory root. They can help at the margins, but SACN’s advice is to get fibre from a variety of food sources, partly because most of the evidence is for fibre as a natural part of whole foods. Dietitians generally treat supplements as a last resort, and they’re worth discussing with a GP or dietitian first.

A 7-day vegetarian meal plan for around 30g of fibre a day

Here’s a week of vegetarian eating that comes out at roughly 30 to 35g of fibre a day. It includes eggs and dairy but no meat or fish, leans on tinned pulses and everyday ingredients, and is built from the foods in the table above so that the totals can be checked. I haven’t counted onions, garlic, herbs, spices, mushrooms, tofu or cooking ingredients, so real totals will be slightly higher. Portions are for an average adult, so adjust them to your appetite, and if your current intake is nearer 20g, build up to this level over a few weeks.

Day	Meals (fibre per meal)	Daily total
Monday	Breakfast: Porridge made with milk, topped with a sliced banana and a tablespoon of chia seeds (9g) Lunch: Jacket potato with baked beans and grated cheese, with sliced tomatoes on the side (9.5g) Dinner: Wholewheat pasta with a tomato, broccoli and carrot sauce and a little grated cheese (11.5g) Snack: An apple and two oatcakes (3.5g)	33.5g
Tuesday	Breakfast: Two wholewheat cereal biscuits with milk, a sliced banana and raspberries (8.5g) Lunch: Lentil and carrot soup with a slice of wholemeal bread (11g) Dinner: Chickpea and pea curry with tomatoes and brown rice (10.5g) Snack: An apple with a tablespoon of peanut butter (3g)	33g
Wednesday	Breakfast: Two slices of wholemeal toast with peanut butter and a sliced banana (8g) Lunch: Egg, avocado and tomato sandwich on wholemeal bread, with carrot sticks (11g) Dinner: Lentil and broccoli dahl with brown rice (10g) Snack: A small handful of almonds (3.5g)	32.5g
Thursday	Breakfast: Porridge topped with raspberries and a tablespoon of chia seeds (9.5g) Lunch: Jacket potato with cheese and sweetcorn (7g) Dinner: Lentil bolognese with wholewheat spaghetti (13g) Snack: An apple (2g)	31.5g
Friday	Breakfast: Scrambled eggs and smashed avocado on two slices of wholemeal toast, with grilled tomatoes (8.5g) Lunch: Baked beans on two slices of wholemeal toast (a double portion of beans) (12g) Dinner: Tofu and vegetable stir-fry with broccoli, carrots and peas, served with brown rice (10g) Snack: Two oatcakes with a tablespoon of peanut butter (2.5g)	33g
Saturday	Breakfast: Porridge with a sliced banana and raspberries, with peanut butter stirred through (8.5g) Lunch: Chickpea, avocado and tomato salad with a slice of wholemeal bread (10g) Dinner: Roasted chickpeas and broccoli with a jacket potato and a yoghurt and herb dip (11g) Snack: A small handful of almonds (3.5g)	33g
Sunday	Breakfast: Vegetable omelette with tomato and sweetcorn, and two slices of wholemeal toast (8g) Lunch: Vegetarian roast with skin-on roast potatoes, carrots, peas and broccoli (13g) Dinner: Chickpea and tomato stew with a slice of wholemeal bread (7.5g) Snack: An apple and two oatcakes (3.5g)	32g

Fibre calculator: how close are you to 30g?

Choose how many portions of each food you eat in a typical day. The calculator adds up your fibre and compares it with the 30g adult target. It’s a rough estimate based on the average values above, and foods that aren’t on the list aren’t counted, so your real total may be a little higher.

Who should be careful with fibre?

For most healthy adults, building up to 30g is straightforward. But fibre isn't right for everyone in every situation. People with irritable bowel syndrome often find that large amounts of fermentable fibre bring on bloating, wind and diarrhoea, and the BDA notes that tolerance varies. Those with inflammatory bowel disease, diverticular disease during a flare-up, a narrowing of the bowel or recent bowel surgery are sometimes advised to eat less fibre for a time.

If you have a digestive condition, speak to your GP or a registered dietitian before changing your diet, and always follow their advice. Children need less fibre than adults, so don't scale up adult portions for them. And if you notice a persistent change in bowel habits, blood in your stools or unexplained weight loss, see your GP rather than trying to fix it with diet.

Dietary fibre FAQs

Is fibre the same as roughage?

Yes. “Roughage” is the older name for dietary fibre, and the NHS still mentions it. Both describe the parts of plant foods that your body can't fully digest.

Do men and women need different amounts of fibre?

Not in the UK. The recommendation is 30g a day for all adults. Some other countries set separate figures for men and women, usually reflecting differences in energy intake.

Is brown bread as good as wholemeal?

No. Brown bread isn't necessarily made from the whole grain. UK food composition data give around 7.4g of fibre per 100g for wholemeal bread, 4.5g for brown and 2g for white, so check that wholemeal or wholegrain flour is the first ingredient on the label.

Why does fibre make me gassy and bloated?

Gut bacteria produce gas as they ferment fibre, and your gut needs time to adapt to a bigger load. It's most common when intake rises quickly or fluid intake is low. Go more slowly, drink more water and give each step a few days. If symptoms persist, especially if you have IBS-type problems, speak to your GP or a dietitian.

Does cooking destroy fibre?

No. A Canadian health guide points out that cooking, chopping or blending doesn't change how much fibre a food contains, although peeling does remove some. Tinned pulses are a convenient way to get plenty.

Do I need a fibre supplement?

Food first. Supplements such as psyllium husk can help some people, but they lack the other nutrients in whole foods, and most of the health evidence comes from fibre eaten in food. If you're struggling to reach 30g, or have a medical reason to supplement, talk to a GP, pharmacist or dietitian.

Can fibre help me lose weight?

It can help at the margins. Soluble fibre slows stomach emptying, and clinical trials have linked higher fibre intakes to slightly lower body weight. But the effect is modest, so it works best as part of an overall pattern of eating rather than as a weight-loss method on its own.

Can I eat too much fibre?

UK guidance focuses on reaching 30g rather than capping intake, but eating a lot more than you're used to, too quickly, is the usual route to bloating, wind and loose stools. If that happens, step back to a comfortable level and build up more slowly.

The bottom line

Fibre is one of the few nutrients where the evidence is strong, the foods are cheap and the target is clear. Thirty grams a day is achievable, yet only a small minority of adults get there, which means almost all of us have room to improve. The way there isn't a heroic overhaul. It's wholemeal instead of white, porridge for breakfast, a tin of beans in the cupboard, skins left on, fruit and nuts for snacks, and a glass of water alongside.

If you like the idea of changes that stick, I wrote about the power of small wins, and fibre is a perfect candidate. Pick two swaps this week, add another next week, and check back in with the calculator in a month.

Sources

• NHS: How to get more fibre into your diet (page last reviewed 2 March 2026)
• Scientific Advisory Committee on Nutrition: Carbohydrates and health (2015) and its press release
• Reynolds A et al. Carbohydrate quality and human health: a series of systematic reviews and meta-analyses. The Lancet, 2019
• Evans CEL. Dietary fibre and cardiovascular health: a review of current evidence and policy. Proceedings of the Nutrition Society, 2020
• Boyle NB et al. Increasing fibre intake in the UK: lessons from the Danish Whole Grain Partnership. British Journal of Nutrition, 2023
• National Diet and Nutrition Survey 2019 to 2023 report (GOV.UK) and the Food Foundation's analysis
• British Dietetic Association: Fibre food fact sheet
• Nutrition claims conditions (Regulation (EC) 1924/2006 annex, legislation.gov.uk)
• York and Scarborough Teaching Hospitals NHS Foundation Trust: High fibre diet leaflet
• HealthLink BC: Lower fibre food choices

Figures and guidance checked on 1 November 2026.