Fibre: requirements, effects & high-fibre foods
The DGE recommends 30 g of fibre a day, but most people in Germany only get around two-thirds of that. What fibre does in your gut, which foods really deliver a lot (with values per 100 g and per serving), how to reach 30 g without bloating, and when a low-fibre diet is the right choice.
Aktualisiert 15 September 2026 · 23 Min. Lesezeit · 30 Quellen
The essentials in 30 seconds
This is the minimum amount of fibre the German Nutrition Society (DGE) recommends for adults. The European Food Safety Authority (EFSA) names 25 g. You can reach this with wholegrains, legumes, fruit, vegetables, nuts and seeds, not with powder.
This is the median amount of fibre men in Germany eat; women eat 18 g (National Nutrition Survey II), around two-thirds of the guideline value; roughly three-quarters stay below 30 g. According to the Max Rubner Institute, there's no more recent representative data.
This is how much lower overall mortality and the risk of heart attack, stroke, type 2 diabetes and bowel cancer are for people who eat the most fibre, compared with those who eat the least (analysis of 185 studies, Lancet 2019).
Meat, fish, eggs, milk, cheese and butter contain 0 g of fibre. Everything that counts comes from grains, legumes, vegetables, fruit, nuts and seeds, mainly from the skin, outer layer and core.
What Is Fibre? Soluble, Insoluble, and What Your Gut Does With It
The name is a 19th-century misunderstanding: fibre was thought to be the part of food that did nothing and only burdened the body. Today we know it's the opposite. Fibre is carbohydrates from plants that the small intestine can't digest: cellulose from cell walls, pectin from apples, beta-glucan from oats, inulin from chicory, resistant starch from cooled potatoes, plus lignin, which strictly speaking isn't a carbohydrate. The EU Food Information Regulation defines it as carbohydrate polymers with at least three building blocks that are neither digested nor absorbed in the small intestine. That's exactly where its value lies: what doesn't disappear in the small intestine arrives in the large intestine, where trillions of bacteria are waiting.
Soluble and Insoluble Fibre: A List
The classic way to categorise fibre asks whether it dissolves in water. Soluble (water-soluble) fibre swells into a gel, slows gastric emptying and the rise in blood sugar, binds bile acids and is almost completely fermented by bacteria in the colon. Insoluble (water-insoluble) fibre binds water without dissolving, increases stool volume and speeds up transit; bacteria can't do much with it. Almost every food contains both, just in different ratios: oats, pulses, apples and flaxseed are rich in soluble fibre, wheat bran, wholegrain bread, nuts and vegetables in insoluble fibre. In practice, this means: if you only eat bran, you get bulk but barely any food for your gut flora; if you only eat porridge, you get the gel but little push. The mix is what matters.
Soluble and insoluble fibre at a glance
- +Pectin: apples, pears, quinces, citrus fruits, berries, carrots; gels, binds bile acids
- +Beta-glucan: oats and barley; proven to lower LDL cholesterol (from 3 g a day, approved health claim)
- +Inulin and oligofructose: chicory, Jerusalem artichoke, onions, garlic, leek, asparagus, bananas; food for bifidobacteria
- +Psyllium husk: swells to many times its size, helps with both constipation and diarrhoea
- +Resistant starch: cooled potatoes, rice, pasta, unripe bananas, pulses; converted into butyrate in the colon
- +Plant gums and mucilage: flaxseed, chia seeds, guar, acacia fibre
- −Cellulose: cell walls of vegetables, fruit skins, wholegrain, pulses; binds water, increases stool bulk
- −Hemicellulose: outer layers of grains, bran, wholegrain bread; speeds up gut transit
- −Lignin: flaxseed, bran, seeds, strawberry seeds; not a carbohydrate, woody, almost non-fermentable
- −Wheat bran: the classic, 10 g a day speeds up gut transit (approved health claim)
- −Nuts and seeds: almonds, hazelnuts, sesame, pumpkin seeds; insoluble fibre plus fat and protein
- −Vegetables: cabbage, kale, fennel, parsnip, artichoke; lots of bulk for few calories
Categorised by solubility in water (Codex Alimentarius, EFSA 2010). More important than soluble or insoluble today is whether a fibre is fermented in the colon: beta-glucan, inulin, pectin and resistant starch are fermentable and feed the microbiome, while cellulose and lignin mainly provide bulk.
What Types of Fibre Are There? Fermentable or Not
The modern way to categorise fibre is less about water and more about bacteria. Fermentable fibre such as inulin, pectin, beta-glucan and resistant starch is broken down by gut bacteria into short-chain fatty acids, mainly butyrate, propionate and acetate. Butyrate is the main fuel for the colon's lining and keeps the gut barrier tight; propionate and acetate travel to the liver and bloodstream, where they affect satiety and sugar metabolism. This type of fibre is also called prebiotic, because it promotes the growth of beneficial bacteria. Poorly fermentable fibre such as cellulose, lignin and wheat bran passes through the colon largely unchanged and works mechanically: it binds water, makes stool softer and bulkier, and shortens the time it spends in the gut. And then there's resistant starch, which sits right in between: it forms when cooked potatoes, rice or pasta cool in the fridge and some of the starch recrystallises. The small intestine can no longer break it down, but the colon can. In one study, the resistant starch content of white rice rose from 0.64 to 1.65 g per 100 g when it was chilled in the fridge for 24 hours and reheated, and blood sugar afterwards rose measurably less steeply; the same effect has been shown for potatoes and pasta. So yesterday's potato salad delivers more food for your colon than a freshly cooked potato, even if the nutrition label doesn't show it.
Fibre: Effects on the Gut, Blood Sugar, Cholesterol and Weight
Hardly any dietary component has been studied as thoroughly as fibre, and the results are rarely this clear-cut. The largest analysis on the topic appeared in 2019 in The Lancet: 185 observational studies and 58 clinical trials covering roughly 135 million person-years combined. The result: people who eat the most fibre have a 15 to 30% lower risk of dying from cardiovascular disease or developing heart attack, stroke, type 2 diabetes and bowel cancer than those with the lowest intake. For every extra 8 g a day, overall mortality and the incidence of these diseases dropped by 5 to 27%. The authors saw the greatest benefit at 25 to 29 g a day, with signs that more is even better. This isn't some miracle effect, but the sum of four mechanisms that show up in the gut, in the blood and on the scale.
Fibre and the Gut: Digestion, Bowel Movements, Microbiome
The most direct effect is mechanical. Insoluble fibre binds water and bulks up the stool, stretching the gut wall, which responds with movement: transit speeds up, stool becomes softer. In a meta-analysis of five studies on chronic constipation, additional fibre intake significantly increased bowel movement frequency; for wheat bran the effect is so well established that the EU has approved the health claim 'wheat bran fibre contributes to an increase in faecal bulk', from 10 g a day. The second effect is biological: fermentable fibre is the main energy source for gut bacteria. They ferment it into short-chain fatty acids, which lower the pH in the colon, inhibit unwanted microbes, feed the cells of the gut lining and reduce inflammation. A low-fibre diet literally starves this system: in mice fed a low-fibre diet over four generations, bacterial diversity was lost step by step, and some species didn't come back even once fibre was reintroduced. That's why you can't build up your gut flora with yoghurt, but with what the bacteria actually eat. And the third effect concerns bowel cancer: in a meta-analysis of 25 studies, the risk dropped by around 10% for every extra 10 g of fibre a day, most clearly for cereal fibre and wholegrain.
Fibre, Blood Sugar and Cholesterol
Soluble fibre forms a gel in the stomach and small intestine that slows down sugar absorption. Blood sugar rises less steeply after a meal, insulin is released more evenly, and over the years this lowers the likelihood of type 2 diabetes: in the Lancet analysis, by 15% for every extra 8 g a day. In people who already have diabetes, a 2020 meta-analysis found that higher fibre intake improved long-term blood sugar (HbA1c) by 2 mmol/mol, LDL cholesterol by 0.17 mmol/l and weight by just over half a kilo; those who ate 35 g instead of the usual 19 g had 14 fewer deaths per 1,000 people over the course of the studies. For beta-glucan from oats and barley, the effect is so well documented that two health claims have been approved: 'beta-glucans contribute to the maintenance of normal blood cholesterol levels', from 3 g a day, and 'consumption of beta-glucans from oats or barley as part of a meal contributes to a reduction in the blood glucose rise after that meal', from 4 g per 30 g of available carbohydrate. The mechanism behind the cholesterol effect: the gel binds bile acids, which the body makes from cholesterol; they're excreted instead of reused, and the liver pulls new cholesterol out of the blood to compensate. Psyllium husk works the same way: around 10 g a day lowered LDL cholesterol by about 0.33 mmol/l in a meta-analysis of 28 studies, roughly 13 mg/dl.
Fibre and Weight Loss: Fullness Without the Calories
Fibre provides hardly any energy, around 2 kcal per gram compared to 4 kcal for digestible carbohydrates, and it fills you up before the calories even arrive: it has to be chewed, swells in the stomach, delays emptying and triggers satiety hormones in the gut via short-chain fatty acids. In the Lancet analysis, people with high fibre intake had lower body weight, and across 62 controlled studies with added viscous fibre, weight (by around 0.3 kg) and waist circumference (by just over half a centimetre) both dropped, even without any calorie targets. That might not sound like much, but it's the difference between a diet and a habit: if you swap white bread for wholegrain, rice for lentils, and the snack bar for an apple, you automatically eat less without counting anything. For anyone trying to lose weight, fibre isn't a trick, it's the foundation: any meal with vegetables, pulses or wholegrain keeps you full longer than the same calories from white flour and sugar.
The social media trend of eating as much fibre as possible has a grain of truth to it (almost everyone eats too little) and a catch: the curve flattens out. Studies show the greatest benefit between 25 and 35 g a day; 50 g or more brings no proven extra benefit, just bloating, and if you're topping up with bran or powder, you're binding minerals like iron and zinc. The amount that counts comes from whole foods, not from a spoonful of psyllium on top.
From plate to large intestine: what happens to fibre in your body
Three stops that explain why fibre fills you up, smooths blood sugar, and yet is still called 'indigestible'. Once you know the journey, you'll also understand why the first few weeks with more fibre can cause bloating, and why that stops.
Mouth and stomach: chewing, swelling, fullness
High-fibre foods need more chewing, and that alone slows down eating. In the stomach, soluble fibres absorb water and form a gel, making the stomach contents thicker and slowing how quickly they leave the stomach. Stretch receptors signal 'full' before many calories have arrived. That's why an apple fills you up longer than the same amount of apple juice.
Small intestine: nothing is absorbed, much is slowed down
Human digestive enzymes can't break the bonds between fibre building blocks. But the gel formed by soluble fibres slows down sugar absorption and binds bile acids that would otherwise return to the liver. The result: a flatter rise in blood sugar and lower cholesterol levels. The fibre itself moves on unchanged.
Large intestine: fermentation and volume
This is where the bacteria take over. Fermentable fibres are broken down into short-chain fatty acids; butyrate feeds the cells of the gut lining, lowers the pH value and keeps inflammation in check. This produces gas, which is why you get bloating during the adjustment phase, until the bacteria have adapted. Insoluble fibres bind water, making stools soft and bulky and shortening transit time to one or two days.
How Much Fibre Per Day? Reference Value, Reality and Your Breakfast
How Much Fibre Per Day?
The German Nutrition Society (DGE) sets a reference value for adults of at least 30 g of fibre a day. This is deliberately a reference value, not a requirement: fibre isn't an essential nutrient whose absence triggers a deficiency disease, but from this amount onwards, the risk of major lifestyle-related diseases measurably drops. The European Food Safety Authority (EFSA) sets the threshold at 25 g, and the Lancet analysis saw the greatest benefit at 25 to 29 g, with risk continuing to fall beyond that. For children and teenagers there's no fixed gram value; the DGE ties intake to energy needs, at least 14.6 g per 1,000 kcal, which is the same density behind the 30 g figure for adults. EFSA considers 25 g sufficient for normal bowel function. The same 30 g applies during pregnancy and breastfeeding too. A 'fibre deficiency' doesn't exist in the medical sense, but the consequences of consistently low intake are well documented: constipation, a depleted microbiome, more frequent diverticula, and higher blood sugar and cholesterol levels.
Fibre Deficiency: How Little We Actually Eat
The last representative survey, the National Nutrition Survey II by the Max Rubner Institute, found a median intake of 18 g for women and 19 g for men, so around two thirds of the reference value. In the detailed analysis using food diaries, the medians were somewhat higher (23 and 25 g), but even there, 68% of men and 75% of women didn't reach 30 g, and among women aged 19 to 24 it was as high as 85%. The most important source is bread, followed by fruit, vegetables and cereal products, and that's exactly where the problem lies: the study notes that bread with a few grains sprinkled on top is often mistaken for wholegrain bread, even though the guidelines require at least 90% wholegrain content; this actually means intake is more likely overestimated than underestimated. The survey dates from 2005 to 2007, and according to the Max Rubner Institute (as of 2026) there's no newer representative data, though nothing suggests the overall picture has fundamentally changed.
A High-Fibre Breakfast: Where the Day Gets Decided
The 30 g doesn't distribute itself evenly across the day. A typical German breakfast of toast, butter and jam provides around 2 g, a croissant with cappuccino even less. If you start the day like that, you need to make up 28 g at lunch and dinner, and that practically never happens. On the flip side, a good breakfast decides half the day: 50 g of oats as porridge with a banana comes to just under 8 g, and with 100 g of raspberries and a tablespoon of ground flaxseed instead of the banana, it's a good 14 g. Two slices of wholegrain bread with cheese and tomato provide 5 g, a homemade muesli of oats, nuts and an apple around 9 g. The calculator below shows where your breakfast stands; the values are calculated from the USDA nutrient database for the amounts stated.
Are You Eating Enough Fibre? The Habit Check
Nobody adds up their fibre intake, and nobody needs to. Intake comes down to a handful of habits: is your bread white or wholegrain, do you eat pulses during the week, how often do you eat fruit and vegetables, do nuts and seeds ever feature, do you peel your potatoes and apples. The list below asks exactly that. The more points that apply to you, the more likely you're under 20 g, and the easier it is to gain 10 g with just one or two changes.
High-fibre foods: list, table and values per serving
There are plenty of lists of high-fibre foods, and most of them lead with wheat bran and chia seeds, because they deliver the most per 100 g. Except nobody eats 100 g of bran. That's why the bars show values per 100 g as the food is actually eaten, so lentils and pasta cooked, nuts and seeds dry, and the notes convert this into portions. The ranking looks quite different then: pulses win, because you eat 150 to 200 g of them, and seeds are the extra that helps throughout the day. All values are taken from the US nutrient database USDA FoodData Central.
Fibre Per 100 g: The Strongest Foods in Two Groups
Values per 100 g cooked or ready to eat, USDA FoodData Central SR Legacy. Per serving: 200 g cooked lentils 15.8 g, 150 g kidney beans 13.9 g, 150 g chickpeas 11.4 g, 50 g oats 5.0 g, 2 slices of wholemeal bread (80 g) 4.8 g, 30 g almonds 3.8 g, 1 tbsp chia seeds (15 g) 5.2 g, 1 tbsp ground flaxseed (15 g) 4.1 g, 1 tbsp sesame (10 g) 1.2 g. Wheat bran tops every table with 42.8 g, 1 tbsp (10 g) gives 4.3 g. Wholemeal pasta cooked 3.9 g, brown rice cooked 1.6 g, quinoa cooked 2.8 g: diluted with water, but the serving is what counts.
Fibre table: 125 foods from high-fibre to low-fibre
The table below lists 125 foods with their fibre content per 100 g, sorted by the thresholds of EU nutrition labelling: from 6 g per 100 g, a food can be advertised as 'high in fibre', from 3 g as a 'source of fibre', below that it's low in fibre. Type in a food or filter by traffic light. The notes state the serving size, because you'd eat 100 g of kale, but not 100 g of wheat bran.
High-fibre diet: how to hit 30 g a day in everyday life
The difference between 11 and 40 g a day isn't different meals, it's different versions of the same meals. The builder below runs the numbers: the white-flour day with toast and jam, orange juice, white pasta with tomato sauce, a cheese roll and a banana comes to around 11.5 g. The wholegrain day with porridge, berries and flaxseed, wholemeal bread with hummus, lentil soup and an apple comes to around 41 g, with similar calories and nothing unfamiliar on the plate. Tick off your own meals and see where you land. The four levers, ranked by impact: legumes two to three times a week (10 to 16 g per serving), an oat breakfast instead of toast (plus 6 to 12 g), wholegrain bread and pasta (plus 3 to 4 g per meal), fruit with skin, berries, nuts and seeds as a snack (plus 3 to 8 g). Just flipping the first lever alone gains you 30 g a week. The DGE sums it up as a rule of thumb: three servings of vegetables, two servings of fruit (one of which can be a handful of nuts), wholegrain cereals and potatoes, and the 30 g follow on their own.
Fibre in drinkable meals and shakes
If you replace a meal with a shake, you usually replace its fibre with nothing: a whey protein shake has 0 g, and a fruit smoothie only keeps its fibre if the whole fruit goes in instead of just juice. With a complete drinkable meal, it's worth checking the nutrition label: does it contain fibre, and how much per serving? As a guide, the EU rule applies: from 1.5 g per 100 kcal, a food can call itself a 'source of fibre', from 3 g per 100 kcal 'high in fibre'. A bottle with 400 kcal should therefore bring at least 6 g, so it doesn't fall behind a normal meal. What fibre is in it shows up in the ingredients list: oat fibre, inulin, acacia fibre and resistant dextrin are common, well-studied sources; they don't replace wholegrains and vegetables for the rest of the day, but they stop the drinkable meal from leaving a gap.
Drinkable meal: a complete meal with fibre
Every bottle delivers 400 kcal, 36 g protein, 26 vitamins and minerals, and depending on the flavour, 7.3 to 7.7 g of fibre, making it a source of fibre under EU rules (1.8 to 1.9 g per 100 kcal). Vegan, cold from the fridge, no kitchen needed. Reference for the percentage: DGE guideline of 30 g a day.
Eating more fibre without bloating: pace, fluids, powder
The most common mistake when switching over isn't the choice of food, but the pace. If you jump from 12 g on Monday to 35 g on Tuesday, you're delivering triple the fermentable material to your large intestine overnight, and the bacteria that could break it down aren't there yet. The result is gas, a bloated stomach and sometimes diarrhoea, and many people give up right at this point. The plan below spreads the switch over four weeks, one lever per week. That's enough for the microbiome to adapt, and it adds up to 30 g.
To 30 g in four weeks: one lever per week
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Week 1
Swap your breakfast
Replace toast or cornflakes with porridge, overnight oats or wholegrain bread. Plus 5 to 8 g a day, without changing anything else. Also, from now on, drink one large glass of water more a day.
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Week 2
Switch bread and sides to wholegrain
Wholegrain bread instead of white, wholegrain pasta instead of regular, potatoes with their skin on, brown rice or bulgur instead of white rice. Plus 3 to 5 g. Bloating during this phase is normal and settles after around three weeks.
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Week 3
Pulses twice a week
Lentil soup, chilli, dal, chickpeas in salad, hummus on bread; tinned versions work just as well. Plus 10 to 16 g on these days. If you're sensitive: start small (100 g), rinse tinned beans, chew well.
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Week 4
Berries, nuts, seeds, skins
A handful of nuts, a tablespoon of ground flaxseed in yoghurt, berries instead of juice, apples and pears with the skin on. Plus 4 to 8 g. You're now at 30 g, with a gut flora that can handle it.
Too much fibre? Fibremaxxing, bloating and what helps
There's no upper limit at which fibre from food becomes dangerous, but there is one at which it becomes uncomfortable, and that's individual. The typical signs of too much at once: bloating, a feeling of fullness, stomach cramps, soft stools or diarrhoea; with too little fluid, the opposite can happen too – hard stools and constipation. If you follow the 'fibremaxxing' trend and use powders to reach 60 g or more, you also risk bran and psyllium binding iron, zinc and calcium. The cause of the discomfort is almost always fermentation: the more fermentable fibre reaches the large intestine, the more gas is produced, until the bacterial community has adjusted. In one study with a highly fermentable fibre, gas production rose by half at the start and was back to baseline after three weeks; the UK's NHS reckons on up to four weeks for the gut to settle. What helps: increase slowly (5 g per week), chew thoroughly, drink enough (fibre binds water, and without enough fluid, stools become harder rather than softer), soak pulses, rinse tinned beans, and in the early stages go for oats, berries and cooked vegetables rather than bran and raw onions. If you still have symptoms after weeks despite a slow increase, you may struggle with certain fermentable carbohydrates; inulin, fructans and galactans from onions, garlic, wheat and pulses are the usual suspects, and the German S3 guideline on irritable bowel syndrome recommends soluble fibre like psyllium husks in such cases – explicitly not wheat bran. And one reason to be cautious: narrowed sections of the gut, for example with Crohn's disease, as well as swallowing difficulties; here, insoluble, fibrous foods should only be on the menu after consulting a doctor (chapter 7).
Almost everyone who has trouble with fibre has a pace problem, not a quantity problem. Your gut needs two, three weeks for the bacteria that can make use of lentils and wholegrain to catch up. If you shift one lever a week and drink half a litre more on top, you'll reach 30 g without a bloated stomach.
Joerg Hauke, Nutrition expert, technical review of this article
Psyllium husks, bran, inulin: fibre as a powder
Fibre powders are the aspirin of nutrition: useful for a specific problem, no substitute for a proper diet. Psyllium husks (psyllium) are the best-studied supplement: 5 to 10 g a day with plenty of water makes stools softer and more regular, but they also help with diarrhoea because they bind water, and they lower LDL cholesterol by around 13 mg/dl. The IBS guideline explicitly recommends them. Wheat bran speeds up gut transit (health claim from 10 g a day), but can make symptoms worse with IBS and binds iron and zinc via phytic acid, so it's not suitable as a long-term solution in large amounts. Oat bran is the gentler option, with beta-glucan for cholesterol. For flaxseed, the German Nutrition Society (DGE) states upper limits: no more than 20 g a day because of cadmium content, and no more than 15 g per meal because of natural cyanide compounds; so one to two tablespoons ground is the portion, not the whole bag. Chia seeds are safe unheated; when baked, they can form acrylamide. Inulin and oligofructose are genuine prebiotics that feed bifidobacteria, but they cause the most bloating; if you take them, start with 2 to 3 g. For all of them: powders provide fibre, but not the vitamins, minerals, plant compounds and filling volume that come with wholegrain, lentils and apples. If you can get to 30 g from food, you don't need any of them.
Fibre binds water. With enough fluid, this makes stools soft and bulky; without fluid, it makes them hard and constipation worse. In a study with 117 people with constipation, 25 g of fibre a day worked significantly better when combined with 2 litres of water instead of 1 litre. Rule of thumb when switching over: half a litre more a day than before, and with psyllium and chia seeds, one large glass of water directly with each portion. Never swallow psyllium or bran dry, and don't take them shortly before lying down.
Low-fibre diet: when less fibre is the right choice
As clear as the evidence is for eating plenty of fibre, there are equally clear situations where the gut temporarily needs a rest. A low-fibre diet, formerly called a 'low-residue' or 'light full diet', reduces intake to under 10 to 15 g a day, reduces stool volume and takes mechanical work off the gut. It's a temporary medical measure, not a way of eating, and there are four typical reasons for it: preparing for a colonoscopy, acute inflammation such as a flare-up of diverticulitis or a gastrointestinal infection, the days after bowel surgery, and narrowed sections of the gut, for example with Crohn's disease or after radiotherapy. In all other cases, including IBS and inflammatory bowel disease during remission, the guidelines explicitly do not recommend a low-fibre diet.
Low-fibre foods: the list
In practice, low-fibre means: no wholegrain, no pulses, no nuts, seeds and kernels, no raw vegetables, no fruit with skin and pips, no cabbage and no onions. What's left is more than it sounds. Grains: white bread, toast, rusks, white rolls, white pasta, white rice, semolina, couscous, cornflakes, peeled potatoes, mashed potato. Vegetables cooked and peeled, without seeds: carrots, courgettes, pumpkin, fennel, parsnip, asparagus tips, finely cooked spinach, tomatoes without skin and seeds, clear or strained soups. Fruit: banana, apple purée, peeled apple, peach and nectarine without skin, melon, stewed fruit, clear juices. Protein: meat, fish, eggs, tofu, milk, yoghurt, quark, cheese, all with 0 g fibre. The table in chapter 5 shows the value for each food; anything with a red light under 2 g is suitable. A low-fibre day then looks like this: toast with cream cheese and a banana in the morning, steamed chicken with mashed potato and cooked carrots at midday, yoghurt or rusks in between, clear soup with white bread and softly cooked courgette in the evening. If you eat like this for several days, add calories and protein deliberately, since the usual filling foods are missing, and then return step by step afterwards. The four stages show in which order.
From a bland diet back to a full diet: four stages
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1
Stage 1under 10 g a day
White bread, rusks, white rice, white pasta, peeled cooked potatoes, broth, banana, apple purée, eggs, fish, lean meat, yoghurt. Only for the days the situation calls for.
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2
Stage 210 to 15 g
Plus cooked, peeled vegetables without seeds (carrots, courgettes, pumpkin, fennel), peeled fruit, fine porridge, light mixed-grain bread. Two to three days, if stage 1 is well tolerated.
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3
Stage 315 to 25 g
Wholegrain bread without whole grains, wholegrain pasta, potatoes with skin, fruit with skin, steamed vegetables in normal amounts, soft pulses pureed (hummus, lentil soup).
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4
Stage 430 g and more
Everything again: whole pulses, nuts, seeds, raw vegetables, seeded bread, berries. From here on, the DGE's target applies, and according to the guideline, it explicitly applies with diverticula too.
Stage values based on the definition from Memorial Sloan Kettering Cancer Center (low-fibre under 10 g) and the DGE reference value. Your treating practice sets the pace and duration for each stage; go back a stage if you get symptoms.
Low-fibre diet before a colonoscopy
The most common situation where someone looks for a low-fibre diet is a colonoscopy. The reason is practical: grains, seeds, skins and fibrous vegetables don't dissolve well in the laxative solution, stick to the gut wall and obscure the view of polyps. The European Society of Gastrointestinal Endoscopy (ESGE) strongly recommends a low-fibre diet the day before the examination in its 2019 guideline; the underlying studies show that a high-fibre diet in the days before measurably worsens preparation. Many German practices go further and require avoiding grains, seeds, nuts, muesli, wholegrain, flaxseed, berries, grapes, tomatoes and kiwi from around two to five days beforehand, because seeds and skins swell up and get in the way of the endoscope. On the day before the colonoscopy, only light, plain food is allowed, then clear fluids from midday or afternoon, followed by the laxative solution. Stick to your practice's instructions, as the timing differs, and a poorly prepared gut often means having to repeat the procedure. After the examination, you can eat normally again straight away, ideally with fibre, since your gut flora needs food after the flush.
A low-fibre diet over weeks reduces bacterial diversity in the gut and provides too little iron, folate, magnesium and plant compounds; in mice, the loss was partly irreversible after four generations. If you eat low-fibre long-term because of symptoms, you should get the cause checked out rather than adjusting your diet. Blood in your stool, weight loss, fever or persistent stomach pain belong in a doctor's practice, not on the menu.
IBS, diverticula, Crohn's disease: what the guidelines say
For three common bowel conditions, the fibre question is often answered incorrectly. Irritable bowel syndrome: The German S3 guideline recommends soluble fibre like psyllium husks as a basic measure, but not insoluble fibre like wheat bran, since it can increase bloating and pain. A general low-fibre diet doesn't help; for persistent symptoms, a time-limited low-FODMAP diet under guidance may be an option. Diverticula: Here, the picture has completely reversed. For decades, grains, nuts and corn were banned in case they got caught in the pouches; large cohort studies found the opposite, and the 2021 S3 guideline on diverticular disease explicitly speaks out against avoiding nuts, grains, corn and popcorn. Instead, it recommends a high-fibre diet of at least 30 g a day for prevention, with the highest grade of recommendation: for every extra 10 g, risk drops by 26%, and at 40 g a day the underlying analysis put risk at just 42% of that for people eating 7.5 g. During an acute flare-up, diet is guided by how things progress and by medical advice, often starting with liquids or light food, then a gradual build-up; the guideline doesn't prescribe a low-fibre diet, and sees no benefit in it even after the flare-up has passed. Crohn's disease and ulcerative colitis: The European nutrition guideline ESPEN explicitly advises against generally avoiding fibre; during remission, a normal high-fibre diet applies. The exception is strictures, meaning narrowed sections of the gut: here, fibrous, insoluble foods (nuts, seeds, raw vegetables, citrus peel, mushrooms) can trigger a blockage and are avoided, while soluble fibre from oats and peeled fruit remains fine. For all three: the decision is made by the treating practice, and 'low-fibre' is almost never the long-term solution.
Frequently asked questions about dietary fibre
What is fibre, explained simply?
Fibre is a type of carbohydrate from plants that the small intestine can't digest: cellulose from cell walls, pectin from fruit, beta-glucan from oats, inulin from chicory, resistant starch from cooled potatoes. It arrives unchanged in the large intestine, where it binds water, bulks up stools and feeds the gut bacteria that ferment it into short-chain fatty acids. Animal foods don't contain any.
Which foods have the most fibre?
Per 100 g, wheat bran (43 g), cocoa powder (37 g), chia seeds (34 g) and flaxseed (27 g) lead the way, but you only eat tablespoons of these. Per portion, pulses come out on top: 200 g cooked lentils provide 16 g, 150 g kidney beans 14 g, 150 g chickpeas 11 g. After that come porridge oats (5 g per 50 g), raspberries (8 g per 125 g), half an avocado (4.7 g), an artichoke (6.8 g), wholegrain bread (2.4 g per slice) and a handful of almonds (3.8 g).
How much fibre a day is healthy?
The DGE recommends adults get at least 30 g a day, the EFSA recommends 25 g. The largest analysis on this (Lancet 2019) saw the greatest benefit from 25 to 29 g, with risk continuing to fall above that. There's no harmful upper limit for fibre from food; bloating tends to increase from around 50 g, and with bran or powder in large amounts, iron and zinc absorption suffers. In Germany, the median is 18 g (women) and 19 g (men), according to the National Nutrition Survey II.
Do eggs contain fibre?
No. Eggs contain 0 g fibre, as do all animal foods: meat, fish, milk, yoghurt, cheese and butter too. Fibre is a component of plant cell walls and storage substances. That said, an egg with wholegrain bread or scrambled eggs with vegetables is still a good combination, since the plant provides the fibre and the egg provides the protein.
Is fish high in fibre?
No, fish is fibre-free. Salmon, cod, tuna and trout contain 0 g fibre, just like meat and eggs. With fish fingers, only the breadcrumb coating provides 1 to 2 g per 100 g. Fish provides protein, iodine and omega-3 fatty acids; the fibre comes from the side dish, such as potatoes with skin, vegetables or lentils.
What is a low-fibre diet and when does it make sense?
A low-fibre diet reduces intake to around 10 to 15 g a day: white bread, white pasta, white rice, peeled cooked vegetables, banana, apple purée, meat, fish, eggs, dairy products; no wholegrain, pulses, nuts, seeds or raw vegetables. It makes sense temporarily before a colonoscopy, during acute bowel inflammation such as a diverticulitis flare-up, after bowel surgery, and with narrowed sections of the gut. It's not suitable as a long-term diet.
Can you eat too much fibre?
From normal foods, practically not. It becomes uncomfortable when the amount increases faster than the gut flora can adapt: this causes bloating, a feeling of fullness and sometimes diarrhoea, usually for one to three weeks. The fix: increase slowly (around 5 g per week), chew well, drink more. Caution is only needed with narrowed sections of the gut and with powders in large amounts, since bran and psyllium can cause constipation without enough water and can bind minerals.
What's the best fibre for your gut?
The mix matters. Fermentable fibre feeds gut bacteria and provides butyrate for the gut lining: beta-glucan from oats and barley, inulin from chicory, onions, leeks and artichokes, pectin from apples and berries, resistant starch from cooled potatoes, rice and pulses. Insoluble fibre from wholegrain, bran, nuts and vegetables provides bulk and speeds up transit. If you eat from both groups daily, you're feeding bacteria and gut wall at the same time; psyllium husks are the best single measure for constipation.
Why is fibre so important with diabetes?
Because they slow down blood sugar after eating. Soluble fibre makes the food mass thicker, so glucose from the meal enters the blood more slowly, the blood sugar spike is flatter, and the body needs less insulin. On top of that, a high-fibre diet is filling with fewer calories, which helps with weight. The analysis by Reynolds and colleagues (2020), covering studies on type 1, type 2 and prediabetes, shows: more fibre lowers long-term blood sugar (HbA1c), fasting blood sugar, cholesterol and weight, and people who eat the most fibre die prematurely less often. The authors state 35 g a day as a target, and the DGE explicitly lists type 2 diabetes among the conditions fibre protects against. In practice, that means: wholegrain instead of white flour, pulses, vegetables and whole fruit instead of juice.
Sources · 30 sources anzeigen
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Writing for Saturo since 2019 about nutrition, nutrients and how to actually get proper nourishment in everyday life.
Hat diesen Artikel am 15. September 2026 auf fachliche Richtigkeit geprüft. This content doesn't replace medical advice.
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