Short answer: Most adults need at least 25 g of fiber a day. WHO recommends at least 25 g, EFSA considers 25 g adequate, the UK advises 30 g, and US and Canadian intakes are 38 g for men and 25 g for women up to age 50. Most people eat far less. Legumes, whole grains, berries, vegetables and seeds close the gap; add them gradually.
Fiber is the part of plant foods your body can’t digest. It adds bulk, helps you feel full and is linked to lower risk of several common diseases. Here are the targets, the best foods and a 30 g example day.
These figures are for healthy people. If you have a flare of inflammatory bowel disease, a narrowed bowel (stricture) or past bowel obstruction, or gastroparesis, or your doctor has prescribed a low-fiber (low-residue) diet, follow medical advice instead. If you take GLP-1 medication, ask your prescriber how fast to add fiber and see what to eat on GLP-1 medication.
How much fiber do you need per day?
The World Health Organization’s 2023 carbohydrate guideline recommends that adults eat at least 25 g a day of naturally occurring dietary fiber, the fiber in whole grains, vegetables, fruits and pulses. EFSA, the European Food Safety Authority, considers 25 g a day adequate for normal bowel function and notes benefits from higher intakes. The UK recommends 30 g.
The US and Canadian Adequate Intake scales with energy: 14 g per 1,000 kcal, or 38 g a day for men and 25 g for women aged 19–50, and 30 g and 21 g from age 51. The current Dietary Guidelines for Americans, 2025–2030 give no gram figure; they say to prioritize fiber-rich whole grains (2–4 servings a day) and eat 3 servings of vegetables and 2 of fruit on a 2,000-calorie pattern.
| Source | Adults | Notes |
|---|---|---|
| WHO (2023) | At least 25 g a day | Naturally occurring fiber from food |
| EFSA (EU) | 25 g a day | Adequate for normal bowel function |
| UK (NHS) | 30 g a day | All adults |
| US and Canada, men | 38 g (19–50), 30 g (51+) | Based on 14 g per 1,000 kcal |
| US and Canada, women | 25 g (19–50), 21 g (51+) | 28 g in pregnancy, 29 g while breastfeeding |
For children, WHO suggests at least 15 g a day at ages 2–5, 21 g at 6–9 and 25 g from age 10. A practical goal for most adults: at least 25 g, working up toward 30 g.
Most people fall short
The average American eats about 16 g of fiber a day, according to MedlinePlus from the US National Library of Medicine, and most UK adults about 20 g, the NHS reports. Going from 16 g to 25 g means adding about 9 g a day: 99 g (½ cup) of cooked lentils (8 g) plus a slice of whole-wheat bread (2 g) would do it.
Soluble vs insoluble fiber: what’s the difference?
MedlinePlus describes the two kinds of fiber like this:
| Type | What it does | Where you find it |
|---|---|---|
| Soluble | Attracts water and turns to gel during digestion, which slows digestion; helps lower cholesterol | Oat bran, barley, nuts, seeds, beans, lentils, peas, some fruits and vegetables |
| Insoluble | Adds bulk to stool and appears to help food pass more quickly through the stomach and intestines | Wheat bran, vegetables, whole grains |
You don’t need to count the two types. Eat a mix of legumes, whole grains, fruit, vegetables, nuts and seeds and you get both.
What does fiber do for your health?
A 2019 series of systematic reviews and meta-analyses in The Lancet, funded in part by WHO, pooled 185 prospective studies and 58 clinical trials:
- Observational studies: people who ate the most fiber had a 15–30% lower risk of dying from any cause or from cardiovascular disease, and of developing coronary heart disease, stroke, type 2 diabetes and colorectal cancer, than people who ate the least.
- Clinical trials: higher fiber intakes lowered body weight, systolic blood pressure and total cholesterol.
- How much: risk reductions were greatest at 25–29 g a day, and higher intakes may bring further benefit.
Observational studies show associations, not proof of cause, and the authors rated the evidence for fiber as moderate certainty. The NHS likewise links fiber to a lower risk of heart disease, stroke, type 2 diabetes and bowel cancer, and notes that it helps prevent constipation.
High-fiber foods: grams per portion
Values are rounded from USDA FoodData Central, with cooked weights for legumes and grains unless noted. For packaged foods, check the label.
| Food | Portion | Fiber | Energy |
|---|---|---|---|
| Split peas, cooked | 196 g (1 cup) | 16 g | 231 kcal |
| Lentils, cooked | 198 g (1 cup) | 16 g | 230 kcal |
| Black beans, cooked | 172 g (1 cup) | 15 g | 227 kcal |
| Chickpeas, cooked | 164 g (1 cup) | 12 g | 269 kcal |
| Bulgur, cooked | 182 g (1 cup) | 8 g | 151 kcal |
| Green peas, frozen, cooked | 160 g (1 cup) | 7 g | 125 kcal |
| Barley, pearled, cooked | 157 g (1 cup) | 6 g | 193 kcal |
| Whole-wheat pasta, cooked | 117 g (1 cup) | 5 g | 174 kcal |
| Rolled oats, dry | 40 g (½ cup) | 4 g | 152 kcal |
| Whole-wheat bread | 2 slices, 64 g | 4 g | 161 kcal |
| Brown rice, cooked | 202 g (1 cup) | 3 g | 249 kcal |
| Food | Portion | Fiber | Energy |
|---|---|---|---|
| Chia seeds | 28 g (1 oz) | 10 g | 138 kcal |
| Raspberries | 123 g (1 cup) | 8 g | 64 kcal |
| Blackberries | 144 g (1 cup) | 8 g | 62 kcal |
| Artichoke, cooked | 1 medium, 120 g | 7 g | 64 kcal |
| Avocado | ½ fruit, 100 g (3.5 oz) | 7 g | 161 kcal |
| Pear, with skin | 1 medium, 178 g | 6 g | 101 kcal |
| Broccoli, cooked | 156 g (1 cup) | 5 g | 55 kcal |
| Apple, with skin | 1 medium, 182 g | 4 g | 95 kcal |
| Potato, baked, with skin | 1 medium, 173 g | 4 g | 161 kcal |
| Almonds | 28 g (1 oz, about 23 nuts) | 4 g | 164 kcal |
| Prunes | 5 prunes, 48 g | 3 g | 114 kcal |
| Flaxseed, ground | 1 tbsp, 7 g | 2 g | 37 kcal |
One cup of cooked lentils, split peas or black beans covers more than half of a 25 g target. Berries give a lot of fiber for few calories; nuts and seeds are calorie-dense.
Fiber on food labels
On US Nutrition Facts labels, the Daily Value for fiber is 28 g; by the FDA’s rule of thumb, 20% DV or more per serving (about 6 g) is high. In the EU, fiber claims are regulated: “source of fibre” needs at least 3 g per 100 g (or 1.5 g per 100 kcal), “high fibre” at least 6 g per 100 g (or 3 g per 100 kcal). More in how to read a nutrition label.
How to get 30 g of fiber a day: an example day
This day reaches about 31 g with everyday foods from the tables above:
| Meal | What you eat | Fiber |
|---|---|---|
| Breakfast | 40 g (½ cup) oats cooked as porridge, topped with 62 g (½ cup) raspberries and 1 tbsp ground flaxseed | 10 g |
| Lunch | Lentil soup with 99 g (½ cup) cooked lentils, plus 1 slice of whole-wheat bread | 10 g |
| Snack | 1 medium apple, with skin | 4 g |
| Dinner | Fish or chicken with 156 g (1 cup) cooked broccoli and 101 g (½ cup) cooked brown rice | 7 g |
| Total | about 31 g |
If you eat about 16 g now, build up to this over a few weeks.
How to add fiber without bloating
A lot of fiber at once can cause gas, bloating and cramps, MedlinePlus explains; adding it slowly helps.
- Increase over a few weeks, one food at a time: whole-grain bread instead of white this week, a daily piece of fruit the next.
- Drink enough fluids. Water helps fiber pass through your digestive system. See how much water to drink a day.
- Start legumes small: a few spoonfuls in a soup or salad.
- Keep the skin and the whole fruit. Eat potatoes, apples and pears with their skins; the US guidelines advise limiting 100% juice.
- Spread fiber over the day rather than packing it into one meal.
Fiber for weight loss: how much helps?
There is no separate fiber target for weight loss. One catch: 14 g per 1,000 kcal shrinks when you eat less (21 g at 1,500 kcal), while WHO’s and EFSA’s 25 g doesn’t, so keep at least 25 g during a calorie deficit.
Fiber can help, modestly. It makes you feel full faster, MedlinePlus notes, and trials in the Lancet analysis showed lower body weight with more fiber. In a 12-month trial in 240 adults with metabolic syndrome, a single goal of at least 30 g of fiber a day led to an average loss of 2.1 kg (4.6 lb), against 2.7 kg (6.0 lb) on the more complex American Heart Association diet; the difference wasn’t statistically significant.
Fiber-rich foods give you volume for few calories: 123 g (1 cup) of raspberries has 8 g of fiber for 64 kcal. Calories still decide the outcome, so weigh calorie-dense sources such as nuts, seeds and avocado.
How Portiva helps
The Today summary card in Portiva shows sugar, fiber and sodium at a glance. Tap it to open Nutrition details (free) for the day or the last 7 days, with fiber measured against your daily fiber target. Portiva sets that target at 14 g per 1,000 kcal of your calorie target, and at least 25 g: about 31 g at 2,200 kcal, 25 g at 1,600 kcal. Pro adds vitamins, minerals and fat types.
Log by photo, live camera scan, voice, text or barcode; every item shows its portion in grams or household measures, editable before saving.
Frequently asked questions
Is 30 grams of fiber a day too much?
Not for most adults. The UK recommends 30 g a day, and the US and Canadian Adequate Intake for men up to 50 is 38 g. If you eat much less now, work up over a few weeks and drink enough fluids. With a bowel condition or a prescribed low-fiber diet, follow your doctor’s advice.
What happens if you eat too much fiber?
Adding a lot quickly can cause gas, bloating and cramps, which often settle as your gut bacteria adjust. MedlinePlus notes that too much fiber may reduce the absorption of minerals such as iron, zinc, magnesium and calcium, usually not a major concern because high-fiber foods tend to be rich in minerals.
Which foods have the most fiber?
Per typical portion, cooked legumes lead: about 16 g in 198 g (1 cup) of lentils or split peas and 15 g in 172 g (1 cup) of black beans, according to USDA FoodData Central. Chia seeds give about 10 g per 28 g (1 oz), raspberries and blackberries about 8 g per cup (123–144 g).
Do fiber supplements count toward my daily fiber?
They add fiber, but the targets are built around food. WHO’s recommendation refers to fiber naturally present in foods, and the American Dietetic Association advises getting fiber from food because few supplements have been studied for their effects. Ask your doctor or pharmacist before starting one.
Sources
- WHO updates guidelines on fats and carbohydrates, World Health Organization (2023).
- EFSA sets European dietary reference values for nutrient intakes, European Food Safety Authority (2010).
- Dietary reference intakes tables: Reference values for macronutrients, Health Canada (2025).
- Dietary Guidelines for Americans, 2025–2030, U.S. Department of Agriculture and U.S. Department of Health and Human Services (2026).
- How to get more fibre into your diet, NHS.
- Fiber, MedlinePlus Medical Encyclopedia, U.S. National Library of Medicine (2026).
- Carbohydrate quality and human health: a series of systematic reviews and meta-analyses, Reynolds A et al., The Lancet (2019).
- Single-component versus multicomponent dietary goals for the metabolic syndrome: a randomized trial, Ma Y et al., Annals of Internal Medicine (2015).
- Position of the American Dietetic Association: health implications of dietary fiber, Slavin JL, Journal of the American Dietetic Association (2008).
- How to Understand and Use the Nutrition Facts Label, U.S. Food and Drug Administration (2024).
- Nutrition claims, European Commission.
- Low-fiber diet, MedlinePlus Medical Encyclopedia, U.S. National Library of Medicine (2024).
- Eating, Diet, & Nutrition for Gastroparesis, National Institute of Diabetes and Digestive and Kidney Diseases, NIH.
- FoodData Central (SR Legacy data), U.S. Department of Agriculture, Agricultural Research Service (2018).