| Americans consume five loaves of
white bread for every loaf of whole wheat. And that's not desirable, say
ARS nutritionists Kay Behall and Judy
Hallfrisch at the Beltsville (Maryland) Human Nutrition Research Center.
White bread is low in fiber. Switching to whole wheat bread is an easy way
for most people to increase fiber intake because two-thirds of the U.S.
population consumes bread or rolls on any given day.
Populations that eat high-fiber diets reportedly have less heart disease,
hypertension, colon cancer, diabetes, and obesity. According to the latest USDA
food consumption survey, American women average a little more than half the
recommended 25 grams of fiber daily, while American men average not quite
three-fourths.
So Behall and Hallfrisch evaluated some health effects of an experimental
bread made with an ultra-fine-ground whole wheat flour. The flour was developed
by ConAgra to make whole-grain products palatable to more people. "Bread
baked with this flour has a taste and texture very similar to white
bread," says Hallfrisch. "And it has six times more fiber."
"We wanted to see if the smaller particle size of the flour would
change glucose tolerance," says Behall, explaining that this test
indicates a person's potential for diabetes. They also wanted to know if
particle size alters how much carbohydrate is fermented in the colon instead of
being digested in the small intestine. Fermented carbohydrates may reduce the
risk of colon cancer, some research suggests, but they can also produce gas.
Twenty-six men and women participated in the study, consuming a glucose
drink, white bread, regular whole wheat bread, and the experimental bread at
four different times.
Behall says the experimental bread improved blood glucose and insulin levels
about the same as regular whole wheat bread. Levels stayed lower compared to
when the volunteers ate white bread or the sugary drink. The researchers
concluded that particle size of the whole-grain flours does not seem to affect
glucose tolerance.
And neither particle size nor fiber content affected the amount of
carbohydrate fermented, says Hallfrisch. All three breads generated about the
same amount of breath hydrogen—a measure of fermentation. And none
produced more gastrointestinal distress than the others.
The ultra-fine-ground whole wheat flour has been used in some commercial
breads, waffles, and other products made by ConAgra and PET, Inc., now part of
Pillsbury, for about 4 years, according to Glen Weaver. He is director of
technical services in ConAgra's flour milling division at Omaha, Nebraska. But
the market is limited because the flour is made from white wheat rather than
the more plentiful red wheat. Weaver is working to gear up U.S. production of
white wheat so ConAgra can market the flour more widely.
A recent policy change by the Food and Drug Administration gives ConAgra
more incentive. Last year, the agency began allowing health claims on the
labels of products containing at least 51 percent whole-grain flours.—By
Judy McBride, Agricultural
Research Service Information Staff.
This research is part of Human Nutrition, an ARS National Program (#107)
described on the World Wide Web at
http://www.nps.ars.usda.gov/programs/appvs.htm.
Kay M. Behall and
Judith G. Hallfrisch are with
the USDA-ARS Diet and Human
Performance Laboratory, Beltsville Human Nutrition Research Center, Bldg.
308, 10300 Baltimore Ave., Beltsville, MD 20705-2350; phone (301) 504-9014, fax
(301) 504-9098.
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