What Is Fiber? What Is Dietary Fiber? Fiber Rich Foods

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Main Category: Nutrition / Diet
Article Date: 22 Apr 2009 - 0:00 PDT

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The word fiber (North American) can also be spelled fibre (British). It comes from the Latin word fibra, meaning fiber, thread, string, filament, entrails. According to the Medilexicon medical dictionary, dietary fiber means "Nutrients in the diet that are not digested by gastrointestinal enzymes." Fiber, in this article, refers just to dietary fiber.

Fiber is also known as roughage. It is the indigestible part of plant foods that pushes through our digestive system, absorbing water along the way and easing bowel movements.

Fiber is made up of non-starch polysaccharides, such as cellulose, dextrins, inulin, lignin, chitins, pectins, beta-glucans, waxes and oligosaccharides. The word fiber is misleading, because many types of dietary fibers are not fibers at all.

Two types of fiber - Soluble and Insoluble

There are two broad types of fiber, soluble and insoluble. Soluble dissolves in water, while insoluble does not.

No fiber can be digested. However, soluble fiber changes as it goes through the digestive tract, where it is fermented by bacteria. Soluble fiber absorbs water, and as it does so becomes gelatinous.

Insoluble fiber goes through the digestive tract without changing its forms.

Dietary fiber foods are generally divided into predominantly soluble or insoluble. Both types of fiber are present in all plant foods, but rarely in equal proportions.

Below you can see the fiber make-up of some foods

Cereal grains - ½ cup cooked

	Soluble	Insoluble
Barley	1g	4g
Oatmeal	1g	2g
Oatbran	1g	3g

Seeds

	Soluble	Insoluble
Psyllium seeds ground (1 Tbsp)	5g	6g

Fruit (1 medium fruit)

	Soluble	Insoluble
Apple	1g	4g
Banana	1g	3g
Blackberries (½ cup)	1g	4g
Citrus Fruit (orange, grapefruit)	2g	2-3g
Nectarine	1g	2g
Peach	1g	2g
Pear	2g	4g
Plum	1g	1.5g
Prunes (¼ cup)	1.5g	3g

Legumes (½ cup cooked)

	Soluble	Insoluble
Black Beans	2g	5.5g
Kidney Beans	3g	6g
Lima Beans	3.5g	6.5g
Navy Beans	2g	6g
Northern Beans	1.5g	5.5g
Pinto Beans	2g	7g
Lentils (yellow, green, orange)	1g	8g
Chick Peas	1g	6g
Black eyed Peas	1g	5.5g

Vegetables (½ cup cooked)

	Soluble	Insoluble
Broccoli	1g	1.5g
Brussels Sprouts	3g	4.5g
Carrots	1g	2.5g

What are the functions of insoluble fiber?

Insoluble fibers have many functions, including moving bulk through the digestive tract, and Controlling pH (acidity) levels in the intestines.

Benefits of insoluble fiber:

• Promotes regular bowel movements and prevents constipation
• Speeds up the elimination of toxic waste through the colon
• By keeping an optimal pH in the intestines, insoluble fiber helps prevent microbes from producing substances which can lead to colorectal cancer

Below are some food sources of insoluble fiber:

• Vegetables - especially dark green leafy ones
• Root vegetable skins
• Fruit skins
• Whole wheat products, wheat bran
• Corn bran
• Nuts and seeds

What are the functions of soluble fiber?

Soluble fiber binds with fatty acids, slows down the time it takes to empty the stomach, and slows down the rate of sugar absorbtion by the body.

Benefits of soluble fiber:

• It reduces cholesterol, especially levels of LDL (bad cholesterol)
• It regulates sugar intake, this is especially useful for people with diabetes and metabolic syndrome

Below are some food sources of soluble fiber:

• Kidney beans
• Pinto beans
• Brussels sprouts
• Broccoli
• Spinach
• Zucchini
• Fruits (raw)
• Apple
• Orange
• Grapefruit
• Grapes
• Prunes
• Grains Oatmeal
• Whole-wheat bread

How much insoluble and soluble fiber should I eat?

Most dietitians say your ratio of insoluble vs. soluble fiber should be 75% to 25%, or 3 parts insoluble to every 1 part soluble. As most high-fiber containing foods usually have both types, it should not be necessary to be too careful about diving them up. Oat, oat brans, psyllium husk and flax seed are rich in both types of fibers. In other words, your focus should be on fiber intake in general, rather than what type of fiber.

If you consume 25g of fiber each day you should meet your daily requirements. Ideally, you should consume 5 servings of fruit and vegetables, as well as some servings of whole grain products, each day.

Fiber is good for you

Eating fiber has many benefits for your health. The consumption of soluble fiber has been shown to protect you from developing heart disease by reducing your cholesterol levels. The consumption of insoluble fiber reduces your risk of developing constipation, colitis, colon cancer, and hemorrhoids.

People with diabetes who consume a lot of fiber tend to need less insulin than those whose fiber intake is low.

A high-fiber intake can significantly contribute towards your body-weight control. Fiber fills you up without adding calories (fiber calories are not absorbed by your body) - this can help treat or prevent overweight/obesity.

Most foods which are high in fiber are also very good for you for other reasons. Take, for example, fruit and vegetables and whole grains, they are high in fiber but also rich in vitamins and other essential nutrients. In other words, if you seek a high-fiber diet, not only will you be protecting your health because of your fiber intake, but also because you will consume other essential nutrients.

Food allergies

If you suffer from good allergies, which often seem to be high-fiber foods, getting the right amount of fiber can be a challenge. With such a wide variety of fiber containing foods around, you should be able to find some that you are not allergic to. When you do find the foods you can tolerate, you may have to forward plan more than other people who do not have food allergies. Pharmacies sell fiber supplements, which can help you bridge the gap.

The following high-fiber foods are the least likely to be allergenic:

• Apple
• Pear
• Melon (fresh)
• Carrots
• Potato
• Swede
• Broccoli
• Green beans
• Pumpkin
• Zucchini (courgette)

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Written by - Christian Nordqvist
Copyright: Medical News Today
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