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High-Fiber Foods

Benefits, Sources, and Getting More Fiber in Your Diet

Improving Emotional Health In This Article

Many of us associate fiber with digestive health and bodily functions we’d rather not think about. However, eating foods high in dietary fiber can do so much more than keep you regular. It can lower your risk for heart disease, stroke, and diabetes, improve the health of your skin, and help you lose weight. It may even help prevent colon cancer. Unfortunately, most of us aren’t eating nearly enough in our diets. By using these tips to add more fiber to your diet, you can help prevent serious disease and look and feel your best.

What is fiber?

Fiber, also known as roughage, is the part of plant-based foods (grains, fruits, vegetables, nuts, and beans) that the body can't break down. It passes through the body undigested, keeping your digestive system clean and healthy, easing bowel movements, and flushing cholesterol and harmful carcinogens out of the body.

Fiber comes in two varieties: insoluble and soluble.

  • Insoluble fiber does not dissolve in water. It is the bulky fiber that helps to prevent constipation, and is found in whole grains, wheat cereals, and vegetables such as carrots, celery, and tomatoes.
  • Soluble fiber dissolves in water and helps control blood sugar levels and reduce cholesterol. Good sources include barley, oatmeal, beans, nuts, and fruits such as apples, berries, citrus fruits, and pears.

Many foods contain both soluble and insoluble fiber. In general, the more natural and unprocessed the food, the higher it is in fiber. There is no fiber in meat, dairy, or sugar. Refined or “white” foods, such as white bread, white rice, and pastries, have had all or most of their fiber removed.

The health benefits of fiber

The latest figures show that nine out of ten Americans are not eating enough fiber; and people in other parts of the world are also falling well short. Part of the problem may be due to the association between fiber and bathroom habits. Yes, fiber offers a healthy and effective way to stay regular. But that’s not the only reason why we should be including more in our diets. Many different studies have highlighted how eating a diet high in fiber can boost your immune system and overall health, and help you look and feel your best. Some of the benefits include:

  • Digestive health. Let’s get this one out of the way first. Dietary fiber normalizes bowel movements by bulking up stools and making them easier to pass. This can help relieve and prevent both constipation and diarrhea. Eating plenty of fiber can also reduce your risk for diverticulitis (inflammation of the intestine), hemorrhoids, gallstones, kidney stones, and provide some relief for irritable bowel syndrome (IBS). Some studies have also indicated that a high-fiber diet may help to lower gastric acid and reduce your risk for gastroesophageal reflux disorder (GERD) and ulcers.
  • Heart disease. Fiber, particularly soluble fiber, is an important element of any heart-healthy diet. Eating a diet high in fiber can improve cholesterol levels by lowering LDL (bad) cholesterol. A high fiber intake can also reduce your risk for metabolic syndrome, a group of risk factors linked to coronary heart disease, diabetes, and stroke. Fiber can help to lower blood pressure, reduce inflammation, improve levels of HDL (good) cholesterol, and shed excess weight around the abdomen.
  • Diabetes. A diet high in fiber—particularly insoluble fiber from cereals—can lower your risk for type 2 diabetes. If you already have diabetes, eating soluble fiber can slow the absorption of sugar and improve your blood sugar levels.
  • Cancer. There is some research that suggests eating a high-fiber diet can help prevent colorectal cancer, although the evidence is not yet conclusive. Diets rich in high-fiber foods are also linked to a lower risk for other common digestive system cancers, including stomach, mouth, and pharynx.
  • Skin health. When yeast and fungus are excreted through the skin, they can trigger outbreaks or acne. Eating fiber, especially psyllium husk (a type of plant seed), can flush toxins out of your body, improving the health and appearance of your skin.

Fiber and weight loss

As well as aiding digestion and preventing constipation, fiber adds bulk to your diet, a key factor in both losing weight and maintaining a healthy weight. Adding bulk can help you feel full sooner. Since fiber stays in the stomach longer than other foods, that feeling of fullness will stay with you much longer, helping you eat less. High-fiber foods such as fruits and vegetables tend to be low in calories, so by adding fiber to your diet, it’s easier to cut calories.

There are other ways that a high fiber intake can aid weight loss. By regulating your blood sugar levels, it can help maintain your body’s fat-burning capacity and avoid insulin spikes that leave you feeling drained and craving unhealthy foods. Eating plenty of fiber can also move fat through your digestive system at a faster rate so that less of it can be absorbed. And when you fill up on high-fiber foods such as fruit, you’ll also have more energy for exercising.

Tips for adding fiber to your diet

Depending on your age and gender, nutrition experts recommend you eat at least 21 to 38 grams of fiber per day for optimal health. Research suggests that most of us aren't eating half that amount.

While hitting your daily target may seem overwhelming at first, the following tips can help you easily add more fiber into your diet. By filling up on whole grains, vegetables, and fruits, you can get most of the fiber you need to start reaping the health benefits.

Making the switch to a high-fiber diet

If you’re new to eating high-fiber foods, it’s best to start by gradually adding fiber to your diet and increasing your water intake. Fiber absorbs water so the more fiber you add to your diet, the more fluids you should drink.

Suddenly adding a large amount of fiber to your diet can sometimes cause side effects such as abdominal cramps, intestinal gas, bloating, or diarrhea. These should go away once your digestive system becomes used to the increase in fiber, but adding fiber gradually and drinking plenty of fluids can help avoid discomfort.

Fiber from whole grains

Refined or processed foods are lower in fiber content, so try to make whole grains an integral part of your diet. There are many simple ways to add whole grains to your meals.

  • Start your day with fiber. Look for whole grain cereals to boost your fiber intake at breakfast. Simply switching your breakfast cereal from Corn Flakes to Bran Flakes can add an extra 6 grams of fiber to your diet; switching to All-Bran or Fiber-One will boost it even more. If those cereals aren’t to your liking, try adding a few tablespoons of unprocessed wheat bran to your favorite cereal.
  • Replace white rice, bread, and pasta with brown rice and whole grain products. Experiment with wild rice, barley, whole-wheat pasta, and bulgur. These alternatives are higher in fiber than their more mainstream counterparts—and you may find you love their tastes. Choose whole grain bread for toast and sandwiches.
  • Bulk up your baking. When baking at home, substitute whole-grain flour for half or all of the white flour, since whole-grain flour is heavier than white flour. In yeast breads, use a bit more yeast or let the dough rise longer. Try adding crushed bran cereal or unprocessed wheat bran to muffins, cakes, and cookies. Or add psyllium husk to gluten-free baked goods, such as breads, pizza dough, and pasta.
  • Add flaxseed. Flaxseeds are small brown seeds that are high in fiber and omega-3 fatty acids, which can lower your total blood cholesterol. You can grind the seeds in a coffee grinder or food processor and add to yogurt, applesauce, or breakfast cereals.

Fiber from fruits and vegetables

Most fruits and vegetables are high in fiber, another good reason to include more in your daily diet. Here are some simple strategies that can help:

How Much Fiber Do You Need?
Minimum Recommended Daily Intake
(in grams)

Age

Male

Female

9-13

31

26

14-18

38

26

19-30

38

25

31-50

38

25

51-70

30

21

Over 70

30

21

Source: Food and Nutrition Information Center, USDA

  • Add fruit to your breakfast. Berries are high in fiber, so try adding fresh blueberries, raspberries, strawberries, or blackberries to your morning cereal or yoghurt
  • Keep fruit and vegetables at your fingertips. Wash and cut fruit and veggies and put them in your refrigerator for quick and healthy snacks. Choose recipes that feature these high-fiber ingredients, like veggie stir-fries or fruit salad.
  • Replace dessert with fruit. Eat a piece of fruit, such as a banana, apple, or pear, at the end of a meal instead of dessert. Top with low-fat ice cream or frozen yogurt for a delicious treat.
  • Eat whole fruits instead of drinking fruit juice. You’ll get more fiber and consume fewer calories. An 8 oz. glass of orange juice, for example, contains almost no fiber and about 110 calories, while one medium fresh orange contains about 3g of fiber and only 60 calories.
  • Eat the peel. Peeling can reduce the amount of fiber in fruits and vegetables, so eat the peel of fruits such as apples and pears.
  • Incorporate veggies into your cooking. Add pre-cut fresh or frozen vegetables to soups and sauces. For example, mix chopped frozen broccoli into prepared spaghetti sauce or toss fresh baby carrots into stews.
  • Bulk up soups and salads. Liven up a dull salad by adding nuts, seeds, kidney beans, peas, or black beans. Artichokes are also very high in fiber and can be added to salads or eaten as a snack. Beans, peas, lentils, and rice make tasty high-fiber additions to soups and stews.
  • Don’t leave out the legumes. Add kidney beans, peas, or lentils to soups or black beans to a green salad.
  • Make snacks count. Fresh and dried fruit, raw vegetables, and whole-grain crackers are all good ways to add fiber at snack time. An occasional handful of nuts can also make a healthy, high-fiber snack.

Eat more fiber-rich foods

Label lingo

A label can claim a food is a "good source" of fiber if it delivers 10% of your daily dose of fiber—about 2.5 grams per serving. The terms "rich in," "high in," or "an excellent source of" fiber are allowed if the product contains 5 or more grams of fiber per serving. Spooning up a bowl of high-fiber cereal is one of simplest ways to reach your fiber target. Look for brands with at least 6 grams of fiber per serving.

Your best bet for bread? Look for the words "100% whole wheat" or "100% whole grain" on the label and at least 3 grams of fiber per slice.

Good Sources of Fiber

Food

Serving size

Fiber
grams

CEREALS

Fiber One

1/2 cup

14

All-Bran

1/2 cup

10

Bran Flakes

1 cup

7

Shredded Wheat

1 cup

6

Oatmeal (cooked)

1 cup

4

VEGETABLES

Spinach (cooked)

1 cup

4

Broccoli

1/2 cup

3

Carrots

1 medium

2

Brussels sprouts

1/2 cup

2

Green beans

1/2 cup

2

BAKED GOODS

Whole-wheat bread

1 slice

3

Bran muffin

1

2

Rye bread

1 slice

2

Rice cakes

2

1

LEGUMES (cooked)

Lentils

1/2 cup

8

Kidney beans

1/2 cup

6

Lima beans

1/2 cup

6

Baked beans (canned)*

1/2 cup

5

Green peas

1/2 cup

4

GRAINS (cooked)

Barley

1 cup

9

Wheat bran, dry

1/4 cup

6

Spaghetti, whole wheat

1 cup

4

Brown rice

1 cup

4

Bulger

1/2 cup

4

FRUIT

Pear (with skin)

1 medium

6

Apple (with skin)

1 medium

4

Strawberries (fresh)

1 cup

4

Banana

1 medium

3

Orange

1 medium

3

DRIED FRUIT

Prunes

6

12

Apricots

5 halves

2

Raisins

1/4 cup

2

Dates

3

2

Plums

3

2

NUTS AND SEEDS

Peanuts, dry roasted*

1/4 cup

3

Walnuts

1/4 cup

2

Popcorn*

1 cup

1

Peanuts*

10

1

Filberts, raw

10

1

* Choose no-salt or low-salt version of these foods

Adapted with permission from Harvard Health Letter, published by Harvard Health Publications.

Fiber in fast food

Fast food is often cheap and convenient, but finding a healthy meal with enough fiber can be a challenge. Many fast food meals are packed with calories, sodium, and saturated fat with little or no dietary fiber. Even a seemingly healthy salad from a fast food restaurant is often light on fiber—simple lettuce greens provide only about 0.5 grams of fiber per cup. Look for salads that include other vegetables, and whenever possible, up the fiber content by adding your own nuts, beans, or corn.

Other tips for getting more fiber from meals at fast food restuarants:

  • Choose sandwiches, burgers, or subs that come on a whole wheat bun or whole grain bread.
  • Try a veggie burger. Many taste much better than they used to and contain two or three times more fiber than a meat burger.
  • Select a side of beans or corn for a healthy fiber boost.
  • Choose nuts or a salad over fries or potato chips.
  • Combining a baked potato and a side of chili, available at some burger chains, can make a tasty, high-fiber meal.
  • Several chains offer oatmeal bowls for breakfast, a higher fiber choice than most breakfast sandwiches. Try to choose lower sugar versions if possible.
  • Finish a fast food meal with a fruit cup, fruit and yogurt parfait, apple slices, or a piece of fresh fruit.

Fiber supplements

While the best way to get fiber in your diet is from foods naturally rich in fiber—fruits, vegetables, whole grains, beans, nuts—when that proves difficult, taking a fiber supplement can help make up the shortfall. Supplements can also be useful to top up your daily fiber intake while you transition to a high-fiber diet.
Fiber supplements come in a variety of forms, including powders you dissolve in water or add to food, chewable tablets, and wafers. However, there are some drawbacks to getting your fiber from supplements instead of fiber-rich foods:

  • Fiber supplements won't provide the same vitamins, minerals, and other nutrients offered by high-fiber foods.
  • Supplements won’t fill you up or help you manage your weight.
  • Fiber supplements can interact with some medications, including certain antidepressants, cholesterol-lowering medications, and the anticoagulation drug warfarin. Check with your doctor or pharmacist about potential drug interactions before taking a fiber supplement.
  • If you have diabetes, fiber supplements may also reduce your blood sugar levels so, again, check with your healthcare provider before adding supplements to your diet.

If you decide to take a fiber supplement, start with small amounts and gradually build up to avoid any abdominal bloating and gas, and drink plenty of fluids.

More help for healthy eating

Resources and references

Dietary fiber: Essential for a healthy diet – The health benefits of fiber and how to fit more into your diet. (Mayo Clinic)

Fibre – Shows how simple changes to what you eat can increase the amount of fibre in your diet. (Canadian Diabetes Association)

High Fiber Diet and Fiber Supplements – Includes fiber contents of different foods and fiber supplements. (Austin Gastroenterology)

Fiber Nutrient List – National Nutrient Database list of different foods with their fiber content. (USDA)

Nutrition Data (commercial site) – Provides searchable database of nutrition labels for many different foods, including restaurant items. (Self.com)

Authors: Lawrence Robinson and Robert Segal, M.A. Last updated: December 2014.