Macronutrient
Fibre
By definition your body cannot break it down. The bacteria in your colon can, and what they make out of it turns out to be most of the reason fibre matters.
What it does
Soluble fibre dissolves and forms a gel. That gel slows how fast the stomach empties, which flattens the rise in blood glucose after a meal, and it binds bile acids so the liver has to make more from cholesterol — which is the mechanism behind oats and LDL.
Insoluble fibre does not dissolve. It adds bulk and holds water, which speeds transit through the colon and is why it is the kind that helps with constipation.
The part that has changed how nutritionists talk about fibre is fermentation. Colonic bacteria ferment some fibres into short-chain fatty acids — chiefly butyrate, which is the preferred fuel of the cells lining the colon. You are, in a real sense, feeding them so that they feed you.
How much you need
| Who | Per day | Note |
|---|---|---|
| Children, 1–3 years | 19 g | — |
| Children, 4–8 years | 25 g | — |
| Boys, 9–13 | 31 g | — |
| Girls, 9–13 | 26 g | — |
| Men, 19–50 | 38 g | — |
| Men, 51 and over | 30 g | — |
| Women, 19–50 | 25 g | — |
| Women, 51 and over | 21 g | — |
| Per 1,000 kcal | 14 g | The figure the others are derived from |
All Adequate Intakes, and average intake in the US and much of Europe is roughly half of them. This is the single largest gap between recommendation and reality of anything on this site.
From our own data
The foods highest in fibre
Legumes, wholegrains, seeds, and fruit and vegetables eaten with their skins. The gap between a wholegrain and its refined version is larger here than for any other nutrient.
- 1
Pine nuts, roasted155% · DV - 2
Chia seeds123% · DV - 3
Linseed98% · DV - 4
Winged beans, dry92% · DV - 5
Rosehips, wild86% · DV - 6
Flax seeds82% · DV - 7
Split peas, dry79% · DV - 8
Poppy seeds70% · DV - 9
Lupin beans, dry68% · DV - 10
Papadum, grilled66% · DV - 11
Unsweetened baking chocolate, liquid65% · DV - 12
Soybeans, roasted and salted63% · DV
Per 100 g, from our copy of USDA FoodData Central, against a Daily Value of 28g. Ranked by amount, not by how much of it your body actually takes up — read the next section before you act on the order.
The table above is per 100 g. The app weighs the portion you actually ate.
What helps, and what gets in the way
Helps
- Increasing intake gradually — a sudden jump causes bloating and puts people off for good
- Drinking enough water, without which extra fibre can make constipation worse
- Variety of type, since different bacteria ferment different fibres
- Eating skins, and choosing whole fruit over juice
Gets in the way
- Refining, which removes the bran where most of it is
- Juicing, which removes essentially all of it
- Some conditions — active flares of inflammatory bowel disease, certain strictures — where a clinician may deliberately restrict it
Fibre supplements are not equivalent to fibre from food. Isolated psyllium or inulin does one or two of the jobs described above; a bowl of beans does all of them and brings minerals, protein and polyphenols with it. Supplements have their place, mostly a clinical one, but they are not a shortcut past vegetables.
Who tends to fall short
Groups where intake or absorption is commonly lower than the reference. It is a list of populations, not a list of symptoms — it cannot tell you anything about yourself.
- Most people in Western countries — average intake is around half the recommendation
- Anyone eating mainly refined grains and few vegetables or legumes
- People on low-carbohydrate diets who have not deliberately replaced the fibre
- Children, whose intake tracks their parents’ closely
Cook it
Black bean, barley and roast squash bowl
Two, about forty minutes
Ingredients
- 150 g pearl barley
- 1 tin black beans, drained
- 500 g squash, cubed, skin on if thin
- 2 tbsp olive oil
- 1 tsp cumin seeds
- Juice of a lime
- A handful of coriander
- Chilli flakes
Method
- 1Barley on firstIt takes 25–30 minutes, longer than anything else here, and it is the only ingredient with a fixed clock.
- 2Roast the squash with its skinThin-skinned varieties need no peeling and the skin is where a large share of the fibre sits. 200°C, 25 minutes, with the cumin seeds tossed through.
- 3Warm the beans in their own liquidA few spoons of the tin liquid rather than water — it is starchy and helps everything cling together at the end.
- 4Combine and dressBarley, beans and squash together, lime over, coriander and chilli on top.
Around 20 g of fibre in one bowl, which is most of a day for an adult woman. If your usual intake is low, build up to this over a couple of weeks rather than starting here — and drink water with it.
Sources
- Dietary Reference Intakes for Energy, Carbohydrate, Fibre, Fat, Fatty Acids, Cholesterol, Protein and Amino Acids
- FDA — Dietary Fiber on the Nutrition Facts Label
- USDA FoodData Central
This page is education, not medical advice. It does not diagnose anything and it is not a substitute for a clinician who knows your history. If you think you are short of fibre, the answer is a blood test and a conversation, not a supplement bought on the strength of an article.
Every food above, and 12,601 more, with the full panel — in the app.