Fiber, total
Today
3-day window. Water-soluble and not stored, so a short run of days is the signal.
What it is
Fibre is the part of plant food you don't digest, so it reaches the colon intact and feeds the bacteria living there. Roughly 95% of people fall short of the recommended amount, which makes it the largest gap in most diets. You cannot get a deficiency disease from lacking it — which is exactly why it gets ignored — but intake tracks strongly with lower rates of heart disease, type 2 diabetes and bowel cancer. Increase it gradually and drink more water, or the first week will be uncomfortable.
Reference intake
Your daily target, personalised to your age and sex.
- AI
- 38 gmale_19_50
- Upper limit
- none established
What the evidence says
Wording reflects how strong the evidence actually is.
Reduces cardiovascular disease risk
Lowers LDL cholesterol
May reduces risk of colorectal cancer
May improves glycemic control and reduces type 2 diabetes incidence
May relieves symptoms in irritable bowel syndrome, though the evidence is thin
Deficiency
Around 95% of US adults consume less than the Adequate Intake (NHANES). There is no deficiency disease, which is a large part of why the shortfall persists.
Early signs
- constipation and straining
- hunger returning soon after meals
- erratic blood glucose after meals
Higher risk
- people eating mostly refined grains and few vegetables
- people on low-carbohydrate diets that were not planned around fibre
- people following a strict low-FODMAP diet beyond the elimination phase
- older adults with low food intake overall
Excess
No upper limit has been set. Very high intakes reached suddenly cause bloating, wind and cramping, and can reduce absorption of minerals — but this is a ramp-rate problem far more than a ceiling problem.
From supplements
- bloating, wind and abdominal cramping, especially when intake rises quickly
- reduced absorption of iron, zinc and calcium at very high intakes
- oesophageal or intestinal obstruction from bulking agents taken with too little water
At extreme doses
Bulk-forming supplements taken without adequate fluid can cause obstruction. This is the one genuine acute risk and it is entirely avoidable.
Absorption
Not absorbed by design — fermented in the colon, yielding roughly 2 kcal/g from short-chain fatty acids
Helps absorption
- adequate fluid intake, without which the bulking effect backfires
- increasing intake gradually over two to four weeks
- variety across fibre types, since different fractions feed different bacteria
- resistant starch formed by cooking and then cooling starchy foods
Hinders absorption
- raising intake abruptly, which produces symptoms that lead people to stop
- low fluid intake
- antibiotic use, which disrupts the fermenting community
Top sources
Per 100 g, in g. FoodData Central IDs are resolved by the importer, not written by hand.
- 34.4 g
Chia seeds
28 g
- 8.7 g
Black beans, cooked
172 g (1 cup)
- 7.9 g
Lentils, cooked
198 g (1 cup)
- 12.5 g
Almonds
28 g
- 10.6 g
Oats, rolled, dry
40 g (1/2 cup)
- 6.5 g
Raspberries, raw
123 g (1 cup)
Ranking these by what you already eat needs the real log — see docs/STATUS.md.
Sources
Last reviewed 2026-08-11