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Fantastic Fibers


“It’s the healthiest gift you can give your body,” was my grandmother’s

breakfast message about the oatmeal she served me 50 years ago.

She would be amused to know that the last 10 years of medical science have given

proof to her intuition about the value of whole oats. Grandma would also chuckle

that I am still following her breakfast advice with added ingredients like fresh

or frozen berries.

Oatmeal and berries have a health value in common; they are not only nutritious

in multiple ways but are also related as great fiber sources with important

health benefits now recognized by the US Food and Drug Administration, Health

Canada and European Medicines Evaluation Authority.

The FDA lists whole oats, barley and psyllium seed husk as excellent sources of

dietary fiber that can reduce cancer risk via regular dietary intake.

Health Benefits of Fiber in the Diet

Consumed as long as people have eaten plants, dietary fiber has recently come

into the view of governments, nutrition advisory groups and the public as one of

our most important dietary macronutrients.

However, nutritionists have estimated that Canadians and Americans consume less

than 50% of the required daily fiber amount to maintain intestinal health and

its multiple other benefits.

Consistent intake of fiber through foods like whole grains, berries and other

fresh fruit, vegetables, seeds and nuts is now associated with reduced risk of

some of the world’s most prevalent diseases including:

· Several types of cancer

· Obesity

· Type 2 diabetes

· High blood cholesterol

· Cardiovascular disease

· Numerous gastrointestinal disorders (constipation, inflammatory bowel

disease, ulcerative colitis, Crohn’s disease, diverticulitis and colon cancer)

Fiber Health Benefits

Recent medical research has proven several physiological benefits of consuming

fiber, among which are:

Improved absorption of calcium, magnesium, and iron

Reduction of blood cholesterol and triglyceride levels

Stabilization of blood glucose levels after a meal, i.e., a low glycemic index

food source

Maintenance of an optimal intestinal environment

Stimulation of immune responses

Over the past 30 years, government agencies around the world have undertaken

analyses and definitions of fiber to more accurately describe this dietary

nutrient. Among some 32 reports filed, the most universally accepted definition

is one by the American Association of Cereal Chemists. The AACC focused on the

physiological and metabolic significance of fiber, defining it as:

“…[T]he edible parts of plants or similar carbohydrates resistant to digestion

and absorption in the human small intestine with complete or partial

fermentation in the large intestine.”

Recognizing these facts, advisories now exist in several countries for

increasing adult intake of dietary fiber to 30 grams per day, double the current

intake levels. Achieving this goal has been difficult because high-fiber foods

do not always taste good and may lack other qualities needed to attract


Resistant Starch and Fermentation Provide Health Benefits

Let’s review some properties of how our bodies use fiber. “Resistant starch”

(same as “resistant carbohydrates”) is a term sometimes used to refer to fiber

sources resistant to complete digestion in the small intestine. These fiber

sources need to pass through to the large intestine perhaps only attracting

water along the way. In the large intestine they undergo fermentation by the

colonic bacteria.

We should remember that fermentation of fiber is normal and healthy, even if

fiber products sometimes cause minor gastric discomfort when the user has not

previously had sufficient fiber in their diet.

“Fermentation” is one normal biological process many people never consider when

they eat healthy foods like fresh berries or vegetables. Fermentation simply is

the breakdown of soluble, resistant starch comprised mainly of carbohydrate

molecules in the large intestine, yielding gases and further useful chemicals

like short-chain fatty acids. A typical property of soluble fibers is to bind

water forming a viscous gel having numerous health benefits during passage

through the digestive system.

Other dietary fiber sources include polysaccharides (starch or sugar chains of

dozens to many hundreds or thousands of units), oligosaccharides (short-chain

sugars, usually 2-20 units long), monosaccharides, lignins and “insoluble” fiber

sources such as cellulose, plant waxes and collagens. Insoluble fiber sources,

however, do not undergo fermentation, but are nevertheless valuable for their

water-attracting properties that aid bowel regularity.

Some of the soluble fiber sources you may see in public news and a variety of

functional foods are:

o Pectins, a seed-like component common in berries, fruits, legumes

o Cellulose from brans and many vegetables

o Beta-glucans in whole oats and barley

o Plant waxes from many edible species

o Polyfructoses from inulin and oligofructans

o Gums and mucillages from tree exudates, fermentation of corn syrup

(xanthan gum), algae (agar, carageenan) and grain seeds (e.g., psyllium seed


Should fiber be new to your diet, add sources of fiber to your diet gradually

over a month. This will allow your intestinal system to adjust slowly until the

30 grams per day of fiber become your normal intake. Drink plenty of water. If

you have persistent discomfort from using fiber sources, speak with your doctor

or a nutritionist.

Fiber Fermentation and Prebiotic Nutrient Value

The process of intestinal fermentation involves action by natural bacteria,

sometimes called flora, residing in our large intestine (primarily the colon).

These bacteria require soluble fiber as fuel and as sources for fermentation to

produce valuable chemicals and health benefits.

Since the fiber serves as food for the bacteria already in the intestine, this

is called a “prebiotic” nutrient value, meaning that before the bacteria can

serve their main purpose in digestion–producing enzymes that digest food–they

must be fed with a substrate they prefer (i.e. fermentable fibers). The main

intestinal flora are bifidobacteria and lactobacilli that are essential for our


Berry pectins, inulin, psyllium and xanthan gum, all mentioned in the above

list, are sources of soluble fibers that provide this prebiotic function in the

normal fermentation process.

The Rubus berries such as the blackberry (Rubus nigra) and red raspberry (Rubus

idaeus) have the highest density of dietary fiber per gram than any other

published food source.

Fermentation is a metabolic process involving the use of one organic source to

create others, such as enzymes to digest food that then release new elements.

Among products of fermentation are gases (methane, carbon dioxide, hydrogen,

nitrogen) and short-chain fatty acids, which result as new molecules clipped

from the more complex digested fiber and food compounds.

Short-chain fatty acids such as butyric acid, acetic acid, propionic acid and

valeric acid make up about 90% of the total fatty acid yield from fermentation

in the human body. Collectively, these fatty acids have several beneficial

physiological effects in the large intestine worth repeating from above.

Fatty acids…

Enhance absorption of calcium, magnesium and iron (thus are important to bone

and blood health)

Contribute to lowering blood cholesterol and triglyceride levels

Promote colon health by raising acidity levels that improve nutrient

absorption and lower risk of colon cancer

Act as anti-inflammatory mediators

Stimulate immune protection through an array of intermediate effects within

the intestinal system, including cytokine production

Appear to inhibit appetite, leading to reduced calorie intake and weight gain.

Insoluble fiber sources from plants, such as cellulose, typically undergo no

fermentation so do not contribute new elements. Rather, they bind water

effectively, making them valuable in digestion as stool softening agents with

the essential benefit of promoting bowel regularity.


Including more fiber in your diet is a crucial step towards a healthier

lifestyle. From oatmeal to berries the combination of ways to creatively

include this nutrient are countless. Why wait?


Wong JM, de Souza R, Kendall CW, Emam A, Jenkins DJ. Colonic health:

fermentation and short chain fatty acids. J Clin Gastroenterol. 40:235-43, 2006.

Kendall CW, Emam A, Augustin LS, Jenkins DJ. Resistant starches and

health. J AOAC Int. 87:769-774, 2004.

Tungland BC, Meyer D. Nondigestible oligo- and polysaccharides

(dietary fiber): their physiology and role in human health and food., Compreh

Rev Food Sci Food Safety 1:73-92, 2002.


Source by Dr. Paul Gross

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