Let’s talk about fiber – the nutrient that doesn’t seem glamorous enough to make many headlines. Yet, fiber has so many benefits that it deserves to be spotlighted and put on a pedestal.

What is fiber? 

There are two types of fiber, dietary fiber and functional fiber. Dietary fiber includes nondigestible carbohydrates that are intact and intrinsic in plants. Functional fiber includes nondigestible carbohydrates that have been isolated, extracted, or manufactured and have been shown to have health benefits to you and me. Within functional fiber, there are soluble and insoluble fibers. Being soluble or insoluble refers to if it is soluble in water or not. Fibers that dissolve in hot water are considered soluble and those that do not dissolve in hot water are considered insoluble. Soluble fibers generally delay substances from being emptied from the stomach, increase how long it takes for substances to move through the intestines, and decrease absorption. Insoluble fibers tend to speed up the time it takes for substances to move through the intestines and increase the bulk of feces. Both types of fiber provide you with health benefits.

When you look at a food label and see fiber, this is referring to functional fibers.

Dietary Fibers Functional Fibers
Cellulose Cellulose
Hemicellulose Pectin
Pectin Lignin
Lignin Gums
Gums B-glucans
B-glucans Fructans
Fructans Polydextrose and polyols
Resistant starches Psyllium
Resistant dextrins
Resistant starches

 

Fiber and Plants

Consuming plant foods provides you with fiber. The plant species, the part of the plant, and the plant’s maturity all influence the composition and the type of fiber that you are getting. You can also see that some fibers are considered both a functional and a dietary fiber depending on how it is included in the food. The plant wall is where most of the fiber is houses within a plant.

Type of Fiber Examples of Food Sources
Cellulose All plant foods, especially wheat bran, legumes, nuts, peas, root vegetables, vegetables of the cabbage family, celery, broccoli, coverings of seeds, and apples
Hemicellulose Whole grains, especially bran, nuts, and legumes
Lignin Whole grains, especially wehat bran, root vegetables, fruits with edible seeds, broccoli (especially the stalk)
Pectin Citrus fruits, strawberries, apples, raspberries, legumes, nuts, some vegetables, oats
Gums Oatmeal, barley, and legumes
B-glucans Oats, barley, mushrooms
Resistant Starches Grains, seeds, bananas (more-green), legumes, potato, rice, pasta
Fructans Chicory, asparagus, onion, garlic, artichoke, tomatoes, bananas, rye, and barley
Chitosan, chitin Shells of crabs, shrimp, lobster

 

Health Claims of Fiber

The Food and Drug Administration (FDA) has approved several health claims for fiber. Diets rich in fiber can lower total risk of death from cardiovascular, infectious, and respiratory diseases. That’s a big statement that has been supported by numerous studies. Research has identified that consuming fiber, both insoluble and soluble, can decrease cholesterol and help reduce blood pressure. Research has also shown that the viscous gels that are formed with the ingestion of fibers helps manage symptoms of diabetes.

One of the reasons I don’t agree with low-carbohydrate diets is because individuals on these diets are often not consuming enough fiber. Which, is actually counter-productive because if you are trying to lose weight, fiber has been shown to help you lose and manage weight. Fiber-rich foods help keep you full longer, reduce hunger, and help manage digestion. Some studies have shown those that individuals who consume more fiber lose more body fat and reduced waist circumference than those who did not consume recommended amounts of fiber.

When you don’t consume enough fiber, your risk for gastrointestinal disorders or issues rises. Diverticular disease, constipation, and colon cancer are highly associated with lower intakes of fiber. The ability of insoluble fiber to help increase stool weight, as well as its ability to speed up transit time in your intestines helps manage gastrointestinal disorders.

Recommendations

The Dietary Guidelines recommend an average of 14 g of fiber per 1,000 kcals. The chart below provides a more specific breakdown of guidelines per total day.

Group Age (years) Total Fiber Recommendations
Men 19 to 50 38
> 50 31
Women

 

19 to 50 25
> 50 21
Children

 

1 to 3 19
4 to 8 25
Girls 9 to 18 26
Boys

 

9 to 13 31
14 to 18 38

 

Unfortunately, most Americans are only consuming about 15 g of fiber each day, which is way below the recommendations for adults and even children. If you want to try to increase your fiber intake, here’s a chart that shows foods that provide you with fiber.

Food Total g

of fiber

Food Total g

of fiber

Apple with skin 2.70 Banana 1.79
Broccoli 4.66 Carrots 3.87
Cauliflower 4.20 Pear with skin 3.16
Black beans 8.7 Kidney beans 7.13
Navy beans 10.5 Pinto beans 6.65
Almonds 12.3 Pecans 9.6
Peanuts 8.1 Walnuts 6.7
Oatmeal 2.1 All bran cereal 29.3
Raisin bran 11.1 Couscous 2.8
Whole grain bread 6.8 Cheerios 10