Soluble fiber has been credited with lowering blood
cholesterol. It may also help people with diabetes by lowering the amount of insulin
necessary to process blood sugar after a meal. When taken with plenty of water before
meals, a soluble fiber supplement binds with water in the stomach and forms a gummy
mass—and that’s what makes us feel full.
Insoluble fiber is the champion of the
gastrointestinal tract. It’s a good natural laxative because it holds onto water and
moves waste quickly through the intestines, says David Beck, M.D., chairman of colon and
rectal surgery at the Ochsner Clinic in New Orleans. It also adds bulk and softens stools.
In general, soluble fibers are found in higher
concentrations in fruits, oats, barley, and beans. When shopping for soluble fiber supplements, you can choose from psyllium, gums, mucilages, glucomannan, or pectins, says
Dr. Beck. Insoluble fibers are more abundant in vegetables, wheat, and cereals;
supplements include wheat bran and flaxseed.
Although it’s helpful to classify fiber as either soluble or insoluble, we need both kinds
in our diets. And fibers don’t always fit neatly into categories. Psyllium,
for example, which is a soluble fiber, promotes bowel movements, a benefit usually
associated with insoluble
fiber. And rice bran, an insoluble fiber, lowers blood cholesterol, which is a trait
of some soluble fibers.
- Some studies have shown a link between high-fiber
diets and a decreased risk of colon cancer, says Dr. Beck. Since
fiber increases the bulk of the stool, it may dilute cancer-causing substances there. It
also moves waste faster through the digestive tract, leaving less time for potentially
harmful or even cancerous substances in your stool to have contact with the lining of the
bowel, he says.
Fiber,
particularly insoluble fiber, is also thought to help prevent hemorrhoids and
diverticulosis, a condition in which small sacs develop in weak areas of the intestinal
wall. It does so by softening stools and speeding up the movement of waste through the
intestinal tract. Fiber may also
help ease the symptoms of irritable bowel syndrome, a condition characterized by
alternating constipation and diarrhea, gas, and cramps.
While much research has focused on the link between fiber and
gastrointestinal health, studies also show that dietary fiber may protect against breast
cancer, according to David P. Rose, M.D., Ph.D., D.Sc., chief of the division of nutrition
and endocrinology for the American Health Foundation in Valhalla, New York. High intakes
of fiber have been shown to reduce estrogen levels in the blood, he says. That’s
important because high levels of estrogen are associated with increased breast cancer
risk.
Fiber may reduce
estrogen by binding with it in the intestine before carrying it out of the body in the
stool. Fiber may also help prevent the reabsorption of estrogen in the blood.
| Supplement forms: Psyllium,
gums, mucilages, glucomannan, pectins, methylcellulose, calcium
polycarbophil, flaxseed, and brans. May help: Colon cancer, breast cancer, heart disease, diverticulosis,
hemorrhoids, constipation, diabetes, overweight, Parkinson’s disease, irritable bowel
syndrome, indigestion,
high
blood pressure, and high cholesterol.
Special
instructions: Do not take with food; always drink at
least eight ounces of water for each tablespoon of fiber that you take.
Who’s at risk
for deficiency: Many
Americans; average consumption is only 10 to 15 grams a day.
Good food sources: All plant foods. The best sources include
wheat-bran cereals, beans, dried figs, peas, raspberries, bulgur, oatmeal, pears, sweet
potatoes, oranges, apples, and barley.
Cautions and
possible side effects: Do not take if you have trouble
swallowing. Talk to your doctor before taking any fiber supplement, especially if you have diverticulitis,
ulcerative colitis, Crohn’s disease, bowel obstruction, or any other serious
gastrointestinal disorder or if you are taking any medications. May cause bloating or
constipation. |
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- Help for the Heart
|
- Studies have shown that people who get the most fiber in their
diets are less likely to have heart disease. In a Finnish study of
nearly 22,000 male smokers ages 50 to 69, men who ate the most fiber, averaging 35 grams
daily, suffered one-third fewer heart attacks than those who ate the least fiber. To look
at it another way, each 10 grams of fiber added to the diet decreased the risk of death
from heart disease by 17 percent.
In a study of 44,000 male health professionals,
those who ate more than 25 grams of fiber a day had a 36 percent lower risk of developing
heart disease than those who ate less than 15 grams daily.
Soluble fiber gets a big chunk of credit for helping
the heart because it’s repeatedly been shown to lower blood cholesterol levels. It
does so in several ways, says Tom Wolever, M.D., Ph.D., professor of nutritional sciences
and medicine at the University of Toronto. When we fill up on fiber, there is less room
for high-fat, high-cholesterol foods. In fact, a growing number of studies show that a
diet rich in soluble fiber will lower blood cholesterol levels by 6 to 8 percent, he says.
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Product Recommendations |
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- Health experts generally recommend that you get your fiber from food,
not supplements, because food contains nutrients that
supplements don’t.
"I don’t often prescribe fiber
supplements, because I want people to change to a whole-foods diet," says William D.
Nelson, N.D., a naturopathic doctor at the Docere Naturopathic Centre in Colorado Springs.
Patients who switch from processed and fast foods to whole foods, including whole grains,
fresh vegetables, fruits, and beans, usually don’t need supplemental fiber, he says.
Sometimes, though, we can’t or won’t get
all the fiber we need. That’s when supplements can help, says Dr. Beck. "Most of
us are very busy. Fiber supplements allow us to worry less about what we’re
eating."
Whether you’re adding more fiber-rich foods to
your diet or taking fiber
supplements, you need to increase your intake gradually. Since fiber isn’t absorbed,
it can ferment in the intestine, causing gas, bloating, cramps, and diarrhea.
Always drink at least eight ounces of water with a fiber
supplement, advises Dr. Beck. Fiber acts like a sponge, and if you don’t drink plenty
of fluids, it can swell and block part of the gastrointestinal tract. It can also block
the esophagus, so experts recommend avoiding fiber supplements if you have trouble swallowing.
Too much fiber can block the absorption of minerals
such as iron, calcium, and zinc. It could also cause calcium losses.
If you supplement, try to get your fiber from a
variety of sources in addition to a high-fiber diet. Look for products like psyllium, apple and grapefruit pectin, guar gum, methylcellulose, and calcium
polycarbophil. At your local health food store, you may also find wheat and oat bran
tablets and multifiber tablets with ingredients like beet and carrot fibers.
Psyllium is a popular and inexpensive fiber supplement
with a laxative as well as a cholesterol-lowering effect, says Dr. Nelson. This supplement
is available in pill, capsule, or powder form. All forms are equally effective, but fiber capsules
and tablets are more expensive than powders.
If you’re taking a tablet or capsule, you have
to take as many as 10 to get the same amount of fiber you’d find in a tablespoon of psyllium seed powder, says Jennifer Brett, N.D., a naturopathic doctor at the Wilton
Naturopathic Center in Stratford, Connecticut. With so many pills to take, people tend to
abandon them more quickly than they do powder supplements.
Psyllium causes gas and bloating in some people. If that happens to
you, try flaxseed, which is easiest to take in capsules or in powdered form.
In addition to fiber, flaxseed contains lignans, compounds that may have anti-cancer,
antibacterial, antifungal, and antiviral effects, says Dr. Nelson.
