How much fiber per day? The 25g target, and why one plate of greens is not enough

Where does the 25g number come from?

In 2023, the World Health Organization (WHO) recommended that adults eat at least 25g of naturally occurring fiber per day, from whole grains, vegetables, fruit and legumes. Children need less, depending on age.

The European Food Safety Authority (EFSA) also chose 25g. The United States counts by energy instead: about 14g for every 1,000 kcal you eat. For men who eat a lot, that number goes past 30g.

Why 25g? Large reviews found that from around this level upward, people are more regular and show better scores on many health markers. These are mostly observational studies, so they tell us things "travel together", not a promise for each individual.

Alongside fiber, WHO also recommends at least 400g of vegetables and fruit a day. Picture about five fistfuls.

Why can a plate of greens not carry the load?

Fresh leafy greens are mostly water, often more than 90%. The fiber is there, but it is diluted.

Compare the fiber in a few familiar foods, using USDA food database figures (rounded):

A few surprises:

• The guava is a quiet star. One guava has more fiber than a whole plate of morning glory.
• Beans are the most fiber-dense of all. 100g of chickpeas is close to three plates of morning glory.
• Swapping white rice for brown rice adds about 2g per bowl without eating anything extra.

Let us try to reach 25g in one day

Here is an ordinary Vietnamese day of eating, no superfoods required:

See? No need for salad three times a day. Just give every meal one "fiber-dense" item: beans, sweet potato, whole fruit or brown rice.

Four small tricks to add fiber without changing your menu

1. Keep the skin when you can. Sweet potato skin, apple peel and guava skin carry lots of insoluble fiber.
2. Replace part of your white rice. Mix one third brown rice into the rice cooker. It still tastes familiar, and the fiber goes up.
3. Add a spoonful of beans. Chickpeas, green peas or black beans sprinkled over rice, soup or salad all work.
4. Eat whole fruit instead of juice. Juicing and straining throws away the pulp, and the pulp is the fiber.

To learn how the kinds of fiber differ, read soluble and insoluble fiber.

Go slow, and remember to drink water

If you currently eat about 10 to 15g a day, do not leap to 30g next week.

Fiber is food for the bacteria in your large intestine. Increase it too fast and the bacteria ferment more and make more gas. Your belly can feel bloated and uncomfortable. Add a little at a time over a few weeks so your microbiome has time to adjust.

And drink enough water. Fiber needs water to soften stools. Without enough water, it can backfire. See also how much water to drink a day.

Frequently asked questions