Fiber: How Much Do You Need?

Tips and ideas to get more fiber in your diet.

By Kathleen M. Zelman, MPH, RD, LD

You probably know that fiber is important to good health, but how do you know if you are getting enough?

Most Americans don't. The average adult only eats 15 grams of dietary fiber per day.

How much fiber do you need? Women need 25 grams per day and men should get 38 grams per day, according to an Institute of Medicine formula based on getting 14 grams of fiber for every 1,000 calories.

Closing the Fiber Gap

Eating more plant foods – vegetables, beans, fruit, whole grains, and nuts – can help and is one of the major recommendations from the U.S. government's 2010 Dietary Guidelines.

These foods are all naturally rich in nutrients, including fiber, and provide all the health benefits that go along with a fiber-rich diet.

Top sources of fiber are: beans (all kinds), peas, lima beans, soybeans, chickpeas, black-eyed peas, artichokes, whole wheat flour, barley, bulgur, cornmeal, bran, raspberries, blackberries, and prunes.

Good sources of fiber include: lettuce, dark leafy greens, broccoli, okra, cauliflower, sweet potatoes, carrots, pumpkin, potatoes, corn, snap beans, asparagus, cabbage, whole wheat pasta, popcorn, nuts, raisins, pears, strawberries, oranges, bananas, blueberries, mangoes, and apples.

Avoiding refined grains -- such as white flour, white pasta, and white rice -- and replacing them with whole grains is a great way to boost the amount of fiber in your diet. The Dietary Guidelines recommend at least half your grains be whole grains, but more is better.

Foods are the preferred way to get fiber, because they also provide nutrients your body needs.

Soluble and Insoluble Fiber

Fiber is present in all plant foods in varying amounts.

Most fiber is classified as soluble (meaning that it partially dissolves in water) or insoluble (meaning that it resists digestion and does not dissolve in water).

Soluble fiber is found in beans, peas, lentils, oatmeal, oat bran, nuts, seeds, psyllium, apples, pears, strawberries, and blueberries. Soluble fiber is associated with lowering LDL (bad) cholesterol, regulating blood sugar, and a lower risk of heart disease and type 2 diabetes.

Insoluble fiber is found in whole grains, barley, couscous, brown rice, bulgur, wheat bran, nuts, seeds, carrots, cucumbers, zucchini, celery, green beans, dark leafy vegetables, raisins, nuts, grapes, and tomatoes. Grandma called it roughage, and one of the benefits of insoluble fiber is that it helps keep you regular, prevents constipation, and reduces the risk of diverticular disease.

Total fiber intake of both kinds, studies show, can lower risk of coronary disease, metabolic syndrome, and obesity.

Foods high in fiber can also make you feel full longer and curb overeating. High-fiber foods are filling; they require more chewing and stay longer in your stomach, absorbing water, and helping you feel full.

Fiber is also associated with lowering risk of certain cancers such as colorectal cancer and other gastrointestinal cancers. Fiber works in concert with other nutrients in a healthy diet to provide the best cancer protection.

Meal Plan Packed with Fiber

Here is a sample healthy meal packed with nutrients and 37 grams of fiber:

• Breakfast: whole-grain bran flake cereal (5 grams of fiber), half a banana (1.5 grams of fiber), and skim milk.
• Snack: 24 almonds (3.3 grams of fiber) and a quarter cup of raisins (1.5 grams of fiber)
• Lunch: Turkey sandwich made with 2 slices of whole wheat bread, lettuce, and tomato (5 grams of fiber), and an orange (3.1 grams of fiber)
• Snack: Yogurt with half a cup of blueberries (2 grams of fiber)
• Dinner:Grilled fish with a salad of romaine lettuce and shredded carrots (2.6 grams of fiber), half a cup of spinach (2.1 grams of fiber), and half a cup of lentils (7.5 grams of fiber)
• Snack: 3 cups popped popcorn (3.5 grams of fiber)

7 Ways to Add More Fiber

Here are seven more ways to add fiber to your diet:

1. Start your day with a whole-grain cereal that contains at least 5 grams of fiber. Look at the list of ingredients to be sure the whole grain (such as whole wheat, whole rye, or whole oats) is first on the list.
2. Read labels and choose foods with at least a few grams of fiber per serving. A good source of fiber contains 2.5-4.9 grams of fiber per serving. An excellent source has 5 grams or more per serving.
3. Use whole-grain breads with at least 2-3 grams of fiber per slice for sandwiches.
4. Choose whole fruit over juice. Whole fruit can have as much as twice the amount of fiber as a glass of juice.
5. Toss beans into your soups, stews, egg dishes, salads, chili, and Mexican dishes. Substitute beans for meat in at least one vegetarian meal per week.
6. Experiment with international cuisines (such as Indian or Middle Eastern) that use whole grains and beans in main dishes.
7. Make snacks count as opportunities to enjoy foods high in fiber. For instance, snack on raw vegetables with bean dip or hummus.

Common Concerns About Fiber

Worried that boosting your fiber intake will cause gastrointestinal distress? Ease into it.

To avoid bloating, gas, and digestive issues, increase fiber in your diet gradually and drink plenty of water, since fiber absorbs water.

A good rule of thumb is to increase the amount of fiber in your diet by about 5 grams a day until you reach your goal and spread dietary fiber throughout the day.

Kathleen Zelman, MPH, RD, is director of nutrition for WebMD. Her opinions and conclusions are her own.