Which foods are highest in dietary fiber?

1 cup of Carob flour gives 41 g of dietary fiber. That is 146% of the Daily Value, and it is the highest of the 1000 foods on this site that has not been fortified.

This ranking is per typical portion rather than per 100 g. Lists built per 100 g end up full of dried herbs and fortified bars, which is technically correct and practically useless, because nobody sits down to 100 g of thyme. Items marked fortified rank where they do because nutrients were added during manufacture, not because the food itself is rich in them.

How to read this list

Carob flour and rye flour lead this table, and neither is what most people will actually change. Read the ranking as a map of where fibre lives rather than as a shopping list: seeds, whole grains, legumes, dried fruit and nuts.

The portions matter here more than usual. A cup of rye flour is a baking ingredient, not a meal. The foods that move the daily total in practice are beans and lentils at around 15 g a cup, a bowl of oats at 4 g, fruit eaten with the skin, and wholemeal bread instead of white.

A gram of fibre is not a gram of fibre

Where it comes from changes what it does. Pooling intervention trials, each gram of cereal fibre added about 2.17 grams to daily stool weight, vegetable fibre 2.03 grams and fruit fibre only 0.88. What separates them is whether your gut bacteria can eat it. Non-fermentable fibre added 2.88 grams per gram, fermentable fibre 0.89. Bran and whole grains bulk. The fibre in fruit gets fermented instead, which is a different job rather than a failure.

Reading a label

USDA's working rule is three grams: that is what makes an item fibre-rich per labelled serving, and the cheapest way to reach it is the less processed version of something you already eat, brown rice instead of white being the standard example. What you will not find beside it is a split between soluble and insoluble with a Daily Value attached. FDA looked for a basis to set one and stated it has none, because no reference intakes were ever established for either. The distinction still means something in your gut. It means nothing on the packet.

Cooking changes the number

Some of a food's fibre is made in your kitchen. A potato baked and then chilled for days turns part of its starch into resistant starch, which behaves like fibre, and in a crossover trial the chilled potato lowered insulin by about a quarter in the first half hour against a hot boiled one. Take it with a pinch. The two potatoes also differed in peeling, cooking method and cooking time, so temperature was not the only thing that changed.

Milling matters too. Porridge from coarse oat flour, around 676 micrometres, gave a lower glucose and insulin rise than the same 40 grams of finely milled oats. Appetite went the other way and was lowest after the commercially milled flour. This was one meal in 20 young lean adults, which is a long way from a week of breakfasts.

Myth. Wholemeal is not automatically gentler on your blood sugar than white. When wheat products were matched for grain, form, particle size and thickness, whole and refined wheat gave little to no difference in glucose response, gastric emptying or appetite, and the only two lower glucose curves belonged to semolina and cracked wheat, both refined. The advantage people expect from wholemeal came from the processing rather than from the bran. This tested wheat, whose fibre is mostly insoluble, and it says nothing about oats or barley.

Myth. Fibre does not steal your iron. Across 32 studies, fibre intake showed no consistent link with iron absorption or with iron status. Two thirds of that evidence is from animals and no pooled effect size was reported, so this is the absence of a consistent signal rather than a demonstrated absence of effect. It is still a better basis than the worry it replaces.

Myth. Fibre added to a product to make it filling usually is not. Across 136 trials, most isolated fibres changed neither appetite ratings nor how much people went on to eat. The exceptions that kept recurring were alginate, guar gum and oat fibre acutely, and resistant maltodextrin over weeks. What separated the fibres that dulled appetite from the ones that did nothing was viscosity, and fermentability showed no such pattern.

What the table cannot show is the other half of the evidence. The studies that found 15 to 30 per cent less heart disease and diabetes in high-fibre eaters were describing whole diets, not a single food. Adding bran to an otherwise unchanged diet is not the same intervention.

Established. A supplement does have one clear use. For chronic constipation, fibre supplements worked in 66 per cent of people against 41 per cent on control, with psyllium doing best, at doses above 10 grams a day and after at least four weeks.

Unsettled. Psyllium is the best-studied fibre there is, and the best single trial of it did not beat placebo. In the review that grades this literature, the highest-quality placebo-controlled psyllium trial showed no significant benefit, and head to head, polyethylene glycol, lactulose, mango and prunes all did better on stool frequency and consistency. Psyllium still earns the strongest grade of any fibre, which says more about the other fibres than about psyllium. The doses behind that grade run from 3.5 grams a day to 22, a sixfold spread, so a pooled claim that psyllium works hides which dose was tested.

For people who are actually constipated, the usual advice looks backwards. Across a network of 17 trials, viscous soluble fibres beat placebo on straining with high certainty and on stool consistency and frequency with moderate certainty. Insoluble fibre, the bran most people reach for first, ranked top on overall symptom score on very low certainty evidence. Rankings out of a thin network move easily, so read that as a reason to try the soluble kind before assuming bran is the answer.

Whole food against a supplement is the comparison people actually want, and the margin is thin. Set against psyllium, fruit came out ahead on how often people went, by about a third of one bowel movement a week, with kiwifruit doing the same. Rye bread beat white bread by roughly four tenths of a movement a week. Prunes matched psyllium and did not beat it. The reviewers call the evidence on whole foods scarce, which is a fair description of numbers that small.

There is a reason this page cannot hand you grams per food and stop. When the trials used real food rather than a powder, they frequently could not say how much fibre actually reached the person or what their background intake was, and very few characterised the fibre by solubility, viscosity or fermentability at all. That is the distance between eat more fibre and eat this much of this. The agency version of the largest review did find the same gram of fibre associated more strongly with bowel outcomes in food than in a supplement, which is the comparison this table is quietly making for you.

Prunes have also been tested on their own, in healthy people who went three to six times a week. Eating 120 grams a day for four weeks added about 33 grams to daily stool weight and moved them from 5.4 to 6.8 bowel movements a week. Whole gut transit time did not change, and wind was significantly more common on prunes than on water.

Myth. Kiwifruit in a capsule does not do what kiwifruit does. Kiwifruit supplements and extracts changed neither how often people went nor what came out. In the same review the one thing that clearly worked was magnesium oxide, where about seven in ten responded against two in ten on control. That is a laxative and a question for a pharmacist or a doctor, rather than a fibre plan.

Two footnotes from the same body of evidence. Whole grain intake showed the same pattern as fibre itself, which is why the advice is usually written as both. And the two other ways people judge carbohydrate, glycaemic index and glycaemic load, held up far worse: smaller or no risk reductions, on low to very low certainty, against moderate certainty for fibre. If you are choosing one thing to pay attention to on a label, fibre is the one with the evidence.

Written from the evidence cards and the data on this page, then checked back against the sources. Bioma Learn has no human medical reviewer at this time and we say so rather than invent one. Information, not medical advice. How we verify.

Full ranking →

Full guide: Fibre: the one nutrient almost everyone is short of, and the numbers behind it

Data: USDA FoodData Central. % Daily Value against the FDA DV of 28 g. Checked 2026-09-15.