Bran, one of the richest sources of dietary fiber, is the indigestible outer
husk of wheat, rice, oats, and other cereal grains. At one time most bran
was discarded when grains were milled. Then in the 1960s Dr. Dennis P.
Burkitt, a British medical officer in Africa, published several scientific
reports in which he theorized that bran and other types of fiber could
prevent heart attacks, diverticulitis and other intestinal disorders, and
cancers of the breast, colon, prostate, and uterus. He developed this theory
after observing that these diseases are rare among rural Africans, who
consume large amounts of whole grains. Prompted by a number of best-selling
books, bran became the fad food of the 1970s, and raw miller's bran was
added to everything from bread to such unlikely dishes as meat loaf and
Since then, much of the enthusiasm for using raw bran has dissipated as
researchers have learned more about its health benefits and possible
hazards. We also know now that various types of bran have different
properties and functions. Wheat bran, for example, is mostly insoluble
fiber; although it absorbs large mounts of water, it makes its way through
the intestinal tract intact. When used in moderation, insoluble fiber helps
prevent constipation by producing a soft, bulky stool that moves quickly and
easily through the coon. excessive amounts, however, should not be taken as
they can cause bloating and intestinal gas.
Does Bran Prevent Colon Cancer ?
Dr. Burkitt had theorized that bran prevented colon cancer by reducing the
amount of time required for the stool to travel through the bowel. But
studies to document this protective effect have produced mixed results. An
Australian study found that women taking large amounts of wheat bran
actually had a slightly increased incidence of colon cancer. In contrast, a
4-year study involving 58 high-risk adults with precancerous colon polyps
found that those taking wheat bran achieved a reduction in the size and
number of these growths.
Two 2003 medical studies – one on Americans and one on Europeans – showed
that high intake of dietary fiber is associated with lower risk of
colorectal cancer. In the American study, investigators compared the daily
fiber intake of more than 3,500 people who had precancerous colon polyps to
the fiber intake of about 34,000 people who did not have these growths. They
found that the people who ate the most fiber, about 35 g daily, had a 27
percent lower risk of precancerous growths than those who ate the least,
about 12 g per day. The association was strongest for fibers from grains,
cereals, and fruits. In the European study, researchers examined the link in
more than 500,000 people in 10 countries. Those who ate the most fiber,
about 35 g daily, had about a 40 percent lower risk of colorectal cancer
compared to those who ate the least, about 15 g a day. An editorial
accompanying publication of the studies concludes, "Eating a diet rich in
plant foods, in the form of fruits, vegetables, and whole-grain cereals
probably remains the best option for reducing the risk of colon cancer and
for general health protection.
It also appears that including wheat bran in a high-fiber diet can help
prevent diverticulitis, an intestinal disorder in which small pockets
bulging from the colon wall become impacted and inflamed. And because it
helps prevent constipation, bran may also be beneficial for persons
suffering from hemorrhoids.
Diabetics may benefit from oat
bran. Oat bran is high in soluble fiber, which is sticky and combines with
water to form a thick gel. Some researchers have reported that this type of
fiber reduces blood cholesterol levels. It also appears to improve glucose
metabolism in diabetics. This benefit, in turn, reduces their need for
insulin and other diabetes medications.
More recently, there have been
reports that rice bran also reduces cholesterol levels. Researchers are not
sure, however, whether this benefit comes from the insoluble fiber found in
the bran or from the highly unsaturated oil in the rice germ – which is not
separated from the grain husks during the milling process.
All types of bran, as well as
other high-fiber foods, play an important role in weight control by
promoting a feeling of fullness without overeating. This may provide an
explanation for the lowered incidence of some obesity-related cancers and
heart attacks among populations whose diets are high in fiber.
When the benefits of bran were
first announced, many people started adding three, four, or even more
tablespoons of raw miller's bran to their daily diet. It soon became
apparent that this practice could cause bloating and discomfort and also
aggravate irritable bowel syndrome. In addition, the phytic acid in raw bran
inhibits the body's absorption of calcium, iron, zinc, magnesium, and other
important minerals. During bread baking, enzymes in yeast destroy much of
the phytic acid. The heat present during processing also destroys most
phytic acid in high-bran cereals. Thus, these processed products are safer
than raw miller's bran.
There have been several reports
of severe bowel obstruction in people who consumed large amounts of bran,
especially if they don't drink enough water. Many nutritionists now advise
people to eat whole-grain wheat bread, cereals, and other products that
contain bran. Have oatmeal and cereals made with whole oats; substitute
brown rice for the white. These foods are more palatable than raw bran,
which tastes like sawdust, and are more beneficial.