Fiber is one of the nutrients Americans most often fall short on. The Dietary Guidelines recommend about 14 grams of fiber per 1,000 calories, which works out to roughly 25 grams a day for many women and 30 to 34 grams for many men. Most people eat around half that.
Why fiber matters
- Digestion: it keeps bowel movements regular and helps prevent constipation.
- Fullness: high-fiber foods are filling for relatively few calories.
- Heart and blood sugar: soluble fiber helps lower LDL cholesterol and slows the absorption of sugar.
- Gut bacteria: fiber feeds beneficial microbes, see the best foods for gut health.
Two types
- Soluble fiber dissolves into a gel: oats, barley, beans, lentils, apples, citrus, psyllium.
- Insoluble fiber adds bulk: whole wheat, bran, nuts, the skins of fruits and vegetables.
Most plant foods contain both, so eating a variety covers you.
The richest sources
- Legumes: a cup of cooked lentils or black beans has about 15 grams.
- Whole grains: oats, barley, bulgur, whole wheat bread and pasta, brown rice, popcorn.
- Vegetables: artichokes, broccoli, Brussels sprouts, peas, carrots, sweet potatoes with skin.
- Fruit: raspberries, pears and apples with the skin, bananas, oranges.
- Nuts and seeds: chia and flax seeds, almonds.
Swaps that add up
- White bread to whole grain bread (check that “whole wheat” or “whole grain” is the first ingredient).
- Sugary cereal to oatmeal or a bran cereal, topped with berries.
- White rice to brown rice, or half and half.
- Add a can of beans to soups, chili, salads and pasta sauces.
- Snack on fruit, vegetables with hummus, or popcorn instead of chips.
- Stir a spoon of chia or ground flaxseed into yogurt or oatmeal.
Increase slowly
Adding a lot of fiber at once can cause gas and bloating. Increase gradually over a few weeks and drink enough water, since fiber works best with fluids.
Supplements
Fiber supplements like psyllium can help some people, but foods provide fiber along with vitamins, minerals and other plant compounds. People with certain digestive conditions should follow medical advice about fiber.
Fiber-rich foods are also the base of a less processed, whole-food diet. For more produce at each meal, see the best ways to eat more fruits and vegetables.
