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But as most health-conscious people know, what’s going
on in the inside matters more.
And what’s going on in the inside—from our digestive health
to measures of whole body health—can often be equated to the amount
of fiber in our diets.
Fiber
Fiber is the elongated, threadlike structures in fruits,
vegetables, and grains that cannot be digested. It has long been recognized
as one of the best food ingredients for maintaining bowel regularity and
preventing constipation. And because it acts to normalize bowel movements,
it can also be used to treat and manage chronic diarrhea (Murray 1996).
Consuming fiber reduces transit time and results in a more thorough evacuation
of waste materials. It is thought to improve all aspects of colon function.
There are two types of fiber: water-soluble and insoluble.
Water-soluble fiber
Water-soluble fiber dissolves in water and is found in oat bran, legumes,
psyllium, nuts, beans, pectins, and various fruits and vegetables. It
forms a bulky gel in the intestine that regulates the flow of waste materials
through the digestive tract.
Water-soluble fiber may lower cholesterol by preventing the reabsorption
of bile acids. Bile acids are made from cholesterol, and after they aid
fat digestion, fiber binds with them and escorts them out of the body.
The liver then has to pull more cholesterol from the blood. In a meta-analysis
of 67 controlled trials, it was found that some water-soluble fibers lower
the total cholesterol and the bad cholesterol (LDL) without affecting
the good cholesterol (HDL) (Brown 1999). A similar double-blind study
found that psyllium lowered LDL cholesterol without affecting HDL cholesterol
(Anderson 1999).
Water-soluble fiber may also stabilize blood sugar by slowing down the
absorption of carbohydrates into the blood. Plus, it can lower blood sugar
levels. Researchers have found that increasing fiber intake results in
a decrease in the body’s need for insulin (Nuttall 1993). Psyllium
supplementation, in particular, has been shown to improve blood sugar
levels in diabetics (Anderson 2000).
Insoluble fiber
Insoluble fiber cannot be dissolved in water, meaning that our bodies
cannot digest it. This type of fiber includes the undissolvable parts
of plant walls and is found in greatest amounts in cereals, brans, and
vegetables. The primary function of insoluble fiber is to collect water
that increases stool bulk in the large intestine. This promotes bowel
movement, and as the bulk works through the intestine, it scours the intestinal
walls of waste matter, reducing the risk of colon-related problems.
Fiber in the diet
Most nutritionists recommend consuming 25 to 40 grams of fiber per day.
The average American consumes 10 to 15 grams. The average Canadian consumes
4.5 to 11 grams.
A variety of epidemiological (disease and population) studies have found
that in populations with high-fiber diets, the incidences of colon cancer,
appendicitis, and diverticulosis are very low. Industrialized countries,
which largely have diets high in fat and low in fiber, have high incidences
of these diseases.
Because fiber is low in calories, it can be added to your diet, providing
a greater feeling of satiety without significantly increasing your caloric
intake. In addition, fiber’s ability to stabilize blood sugar may
also curb the desire to snack. In other words, you may find yourself eating
less. This is beneficial in weight-loss programs.
Psyllium
Psyllium, a soluble fiber grown in India, has more than
eight times the bulking power of oat bran. In 1998, the U.S. Food and
Drug Administration approved the health claim that foods containing psyllium
may reduce the risk of coronary heart disease. This is due to its cholesterol-lowering
effect.
Manufacturers of foods containing psyllium may use the claim with certain
restrictions. When making the claim, they must state that it is in conjunction
with a diet low in saturated fat and cholesterol, that adequate amounts
of fluids must be consumed with the food, that there is a potential for
choking if fluids are not consumed with the food, and that people with
difficulty swallowing should avoid consumption of the food. As well, the
food must provide at least seven grams of soluble fiber per day.
A model claim would be: The soluble fiber from psyllium seed husk in this
product, as part of a diet low in saturated fat and cholesterol, may reduce
the risk of heart disease. A serving of this product supplies X grams
of the 7 grams of soluble fiber necessary to have this effect. Adding fiber to your diet
Once you understand what fiber is and what it does, the next step is changing
your diet to make sure you increase your fiber intake.
- Eat at least five servings of fruits and vegetables per day. Fruits
and vegetables that are high in fiber include apples, oranges, broccoli,
cauliflower, berries, pears, Brussels sprouts, lettuce, figs, prunes,
carrots, and potatoes.
- Switch from white bread to whole-grain breads and cereals. Switch from
white rice to brown rice.
- Eat dry bran cereals for breakfast. Be sure to check the label to
see how much fiber the cereals contain. Some have less fiber than you
would think.
- Add one-fourth cup of wheat bran to foods, such as cooked cereals, applesauce,
and meat loaf.
- Eat beans each week.
- Add a fiber supplement to your diet.
Remember, as you increase your fiber intake, increase the amount of water
you drink. To experience the benefits of fiber, adequate water is necessary.
Experience and research indicate that fiber is an indispensable part of
your diet. Including adequate fiber in your diet can help prevent many
of today’s prevalent health care concerns.
Resources
Anderson, J.W.; L.D. Allgood; J. Turner; et al. “Effects
of Psyllium on Glucose and Serum Lipid Response in Men with Type II Diabetes
and Hypercholesterolemia.” Am J Clin Nutr 70 (1999): 466-73.
Anderson, J.W.; M.H. Davidson; L. Blonde, et al. “Long-Term Cholesterol-Lowering
Effects of Psyllium as an Adjunct to Diet Therapy in the Treatment of
Hypercholesterolemia.” Am J Clin Nutr 71, no. 6 (2000): 1,433-8.
Brown, L.; B. Rosner; W.W. Willet; F.M. Sacks. “Cholesterol Lowering
Effects of Dietary Fiber: A Meta-Analysis.” Am J Clin Nutr
69 (1999): 30-42.
Nuttall, F.W. “Dietary Fiber in the Management of Diabetes.”
Diabetes 42 (1993): 503-8.
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