Addressing the Fiber Gap

Addressing the Fiber Gap

Robyn Flipse, MS, MA, RDN — January 29, 2019

The Dietary Guidelines for Americans (DGA), first published in 1980 and revised every five years since, have each contained recommendations that provide ample sources of dietary fiber to meet every American’s needs.   If all Americans ate the recommended daily servings of whole grains; beans, peas and lentils; nuts and seeds; vegetables; and fruits there would be no “fiber gap,” or shortfall between our consumption of fiber and our requirements.  But Americans are not eating the recommended servings each day, or most days, of the foods rich in this indigestible carbohydrate that provides numerous health benefits (1).

The reasons Americans don’t consume enough dietary fiber are as diverse as the population itself. For some, it is simply a matter of taste preferences. Many who are “finicky eaters” in childhood grow up to be adults who still won’t eat broccoli.  For others, the reason is time constraints. Their schedules are so full they don’t believe they have the extra 20 minutes it takes to cook brown rice instead of white or slice a tomato for their sandwich.  Other reasons include perceived higher cost of high fiber foods, limited cooking skills to prepare them, lack of awareness about their options, and concern over digestive issues to name a few.

Whatever the reason for not eating enough fiber, the first step to closing the gap requires a change in one’s dietary pattern.

The 2015-2020 DGA acknowledge that no individual food or nutrient is more important to our health than our overall dietary pattern (2). That is because dietary patterns reflect the amounts, variety and combinations of the different foods and drinks we regularly consume. Dietary patterns can also provide insight into where and when we eat, with whom, and how our food was prepared. (3). They are the key to knowing what our usual caloric and nutrient intake is over time.

If adequate amounts of fiber-rich foods are not part of someone’s dietary pattern, their habitual way of eating will have to be modified to incorporate them. This requires changes in long-established eating behaviors.

There is no one best way to help individuals, let alone entire populations, change their dietary patterns, but one method that has broad appeal is the use of “nudging” (4).  Nudge theory was popularized in the 2008 book, Nudge, co-authored by Richard Thaler and Cass Sunstein, and helped Richard Thaler win a Nobel Prize in Economics in 2017 (5).Simply stated, nudge theory encourages people to make decisions that are in their own best self-interest by making it easier for them to do so.

The current recommendations for fiber intake are 14 grams for every 1000 calories or a total of 25 – 38 grams a day for adults. These are difficult goals for most people to comprehend, let alone calculate. But if we nudge someone to eat just one more serving a day of a good source of fiber from choices that are already part of their dietary pattern, they have a goal that is both doable and sustainable.

For example, if someone eats lunch in their school or workplace cafeteria every Monday through Friday and makes a salad from the salad bar, we can encourage them to add one more serving of a fiber-rich food to their bowl. This could be 6 cherry tomatoes, ½ cup chickpeas or barley salad, or 2 tablespoons of sunflower seeds or dried cranberries. They don’t have to know how many grams of fiber they added or go out of their way to find these options. They just have to add one more serving of a vegetable, bean, grain, seed or fruit that they like and is right in front of them.

The next nudge to add one more serving could be to put an extra can of kidney beans in their homemade chili or mix a cup of frozen lima beans into a can of minestrone soup or blend some chopped walnuts with the bread crumbs they’re using to coat chicken cutlets. Little by little these nudges can help people increase their fiber intake by using foods that fit within the framework of their existing dietary pattern.

There are endless ways to “nudge” more sources of fiber into a dietary pattern by using higher fiber options in place of, or in addition to, the foods already being eaten, including the use of foods containing added fiber. The chart below provides examples of some ways to get started.

By replacing a Current Choice with the New Choice illustrated below, fiber intake can be nudged higher with each selection.


Current Choice Portion Size Fiber (grams) New Choice Portion size Fiber (grams)
Bagel, pumpernickel 3.5” diameter 3 Bagel, whole wheat 3.5” diameter 8
Bread, whole wheat 1 ounce slice 3 Bread, whole wheat with added fiber 1 ounce slice 7
Pasta, white 2 ounces dry 1 Pasta,  with added fiber 2 ounces dry 6
Corn Flakes 1 ounce 1 Bran Flakes 1 ounce 5
Tortilla, flour 1 ounce 0 Tortilla, whole wheat 1 ounce 2


Yam, cubed without skin ½ cup 2 Yam, cubed with skin ½ cup 4
Spinach ½ cup 2 Collard Greens ½ cup 4
Hearts of Palm, canned 3 pieces 2 Artichoke Hearts, canned 3 pieces 3
Tomato Juice 1 cup 1 Vegetable Juice 1 cup 2
Zucchini Squash 1 cup 2 Acorn Squash 1 cup 6
Lima Beans ½ cup 4 Edamame, shelled ½ cup 9


Strawberry Milkshake 8 ounces < 1 Strawberry Smoothie 8 ounces 3
Peach medium 2 Pear medium 5
Pineapple 1 cup 2 Kiwi 1 cup 5
Fruit Leather 1 ounce 0 Apricots, dried 1 ounce 2
Grapes 1 cup 1 Raspberries 1 cup 8
Jam, concord grape 1 tablespoon 0 Jam, concord grape with added fiber 1 tablespoon 3


Tofu, firm ½ cup 3 Split peas, cooked ½ cup 8
Peanuts 1 ounce 2 Almonds 1 ounce 4
Black-eyed peas ½  cup 5 Navy beans ½ cup 9
Sesame seeds 1 tablespoon 1 Chia Seeds, dried 1 tablespoon 4
Sunflower Seeds 1 ounce 3 Pumpkin Seeds 1 ounce 5
Butter, salted 2 tablespoons 0 Peanut Butter, creamy 2 tablespoons 2

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* Values are averages for similar items and rounded to nearest whole number


  • Discuss the changes in bowel frequency and possible flatulence up front to avoid unexpected problems that could derail someone’s commitment.
  • Show respect for individual food preferences by basing recommendations on what clients like rather than the foods highest in fiber, many of which they may not like.
  • Avoid leading with the message that it is “easy” or “simple” to change one’s dietary pattern when it isn’t, but it can be done when the change is not too disruptive to one’s established routines.
  • Always include lower cost options in messaging, such as using canned, frozen and dried fruits and vegetables, to reinforce the fact all forms contribute needed fiber and other nutrients.
  • Make it clear the fiber in foods is not destroyed by preparation methods, such as chopping and pureeing or by temperature changes, such as boiling and freezing.
  • Suggest foods containing added fiber(s), such as granola bars, yogurts, and pasta, to replace lower fiber choices they may now be consuming.
  • Remind them that the claim “Made with Whole Grains” does not mean the food is a significant source of fiber so they must use the fiber information on the Nutrition Facts Panel to compare these foods to other products.
  • Look for the claims “High in Fiber” or “Good Source of Fiber” on product labels to easily find higher fiber foods.
  • Recommend fiber from a variety of food sources that contain different types of fiber since they have different benefits.
  • Encourage the use of QR scans and websites to find fiber information for foods that don’t have labels, like fresh fruits and vegetables and bulk grains and seeds.


  1. Hoy MK, Goldman JD. Fiber intake of the U.S. population What We Eat in America, NHANES 2009-2010. Food Surveys Research Group Dietary Data Brief No. 12. September 2014.
  2. S. Department of Health and Human Services and U.S. Department of Agriculture. 2015-2020 Dietary Guidelines for Americans. 8th Edition. December 2015
  3. Tucker KL. Dietary patterns, approaches, and multicultural perspective. Appl Physiol Nutr Metab. 2010;35(2):211-218 doi: 10.1139/H10-010.
  4. Arno A, Thomas S. The efficacy of nudge theory strategies in influencing adult dietary behaviour: a systematic review and meta-analysis. BMC Public Health. 2016;16:676. doi:10.1186/s12889-016-3272-x.
  5. Thaler RH, Sunstein CS. Nudge. Improving Decisions About Health, Wealth, and Happiness. 2009, Penguin Books, London.


Items of Interest

January 29, 2019