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A comprehensive guide to the
amounts of flavonoids in some 224 different foods is now available on the World
Wide Web. This authoritative new database is the work of ARS scientists from
the Beltsville (Md.) Human Nutrition Research Center, working with colleagues
at the ARS Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts
University, Boston, Mass., and industry experts.
As more data become available,
other food items will be added.
Flavonoids, plant compounds that
are thought to have healthful properties, include anthocyanidins in blueberries
and cherries; catechins in tea, red wine, and apples; and quercetin in onions
In addition to antioxidative
effects, certain flavonoids may have antimicrobial, anticarcinogenic, and
cardioprotective properties, as well.
Researchers who are evaluating
associations between flavonoid intake and reduced risk of certain diseases
should find the new database especially useful. To access it, go to:
http://www.nal.usda.gov/fnic/foodcomp.
Under the red "Food Composition Products" label, click "Flavonoids."
For more information, contact
Joanne M. Holden, (301) 504-0630;
USDA-ARS Beltsville Human Nutrition
Research Center, Beltsville, MD
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Ongoing laboratory studies by ARS
scientists may add to the list of compounds in foods that help reduce the risk
of a disorder known as insulin resistance. About 16 million Americans are
insulin-resistant, meaning that they can't properly use insulin to get
energy-rich glucose from their blood into cells that need it.
Insulin resistance often leads to
type 2 diabetes, the most common form of diabetes in the United
States.
Scientists at the ARS Western
Regional Research Center, Albany, Calif., have developed insulin-resistant
laboratory hamsters and are now using the animals in novel studies. Insulin
resistance occurred in the lab animals within only a few weeks after the
researchers put the hamsters on a high-fat regimen, similar in proportion to
the amount of fat that most Americans eat every day.
The experiments should identify
food compounds that protect the animals from becoming insulin-resistant. Use of
laboratory animals that are insulin-resistant isn't new. But the California
researchers are likely the first to develop this condition in hamsters by
increasing the amount of fat that the animals consumed.
For more information, contact
Qiming Shao, (510) 559-5669; USDA-ARS
Western Regional Research Center, Albany,
CA
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A 40-foot-long mobile research lab
is now bringing nutrition studies to people and communities that previously
might not have been included in these investigations.
The customized van enables
scientists based at the ARS Grand Forks (N.D.) Human Nutrition Research Center
to reach youngsters, the elderly, and other individuals who generally
aren’t able to easily travel to research facilities.
The scientists designed and
equipped their on-the-go lab with everything that they require to evaluate
volunteers' eating habits, nutritional status, general physical and mental
health, and other factors key to the investigations.
For instance, the researchers have
already taken their mobile lab to three of North Dakota’s four Native
American reservations to collect needed data. The scientists will use study
results to develop recommendations to improve nutrition in these
communities.
For more information, contact
James G. Penland, (701) 795-8471;
USDA-ARS Grand Forks Human Nutrition
Research Center, Grand Forks, ND
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Mannitol--the pleasant-tasting,
powdery coating on chewing gum, hard candy, and pills--might soon be made with
the help of a hard-working microbe.
Most of today's mannitol is
manufactured using a relatively inefficient process. However, scientists at the
ARS National Center for Agricultural Utilization Research in Peoria, Ill., now
have shown that a strain of beneficial Lactobacillus intermedius can
produce mannitol from sugar such as high-fructose corn syrup. It can do that
more efficiently than current commercial processes.
USDA has patented the microbe and
the technology for using it and now is working with a company to commercialize
the research.
Mannitol has fewer calories than
sugar and is used as a low-calorie sweetener.
For more information, contact
Badal C. Saha, (309) 681-6276;
USDA-ARS National Center for Agricultural
Utilization Research, Peoria, IL
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People who eat animal-derived foods
such as meat, poultry, or dairy products are likely to lose more calcium from
their bones than people who eat less of these items, one theory in nutrition
research suggests.
But scientists at the ARS Western
Human Nutrition Research Center at Davis, Calif., and their university
colleagues have findings that run counter to that idea.
The scientists analyzed the eating
patterns and key bone-health indicators of 48 healthy, nonsmoking women, aged
18 to 40, who volunteered for a 10-month study. Twenty-two of the volunteers
were vegans, who don't eat animal products, and 26 of the women were omnivores,
who do.
Contrary to what previous research
had suggested, the rate at which calcium was removed from bones of the
volunteers--for other uses by their bodies--was the same for omnivore women as
for the vegan women.
A second unexpected finding: the
vegan volunteers formed new bone at a significantly faster rate than the
omnivore volunteers. That happened even though the vegans were eating less
calcium than the omnivores. Both the vegans and the omnivores took in about the
same amount of other bone-building nutrients, such as magnesium.
The study is part of ongoing
research at the Davis nutrition center to identify nutrition-based ways to
reduce the risk of osteoporosis. This disease causes dense, healthy bones to
become weak, thin, porous, and more likely to fracture. An estimated 10 million
Americans have osteoporosis. Another 28 million are at risk.
For more information, contact
Marta D. Van Loan, (530) 752-4160;
USDA-ARS Western Human Nutrition Research
Center, Davis, CA
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Vitamin K may be essential to one
aspect of bone health for women, but not necessarily for men. Scientists funded
by ARS looked at vitamin K intake from food and at bone mineral density
measures from the hip and spine of male and female participants in the
1996-2000 Framingham Heart Study. Low mineral density at the hip and
spine--indicative of porous bone--may increase risk of fractures.
The investigators found that the
Framingham women who had the lowest vitamin K intake also had, on average,
significantly lower bone mineral density. That was in comparison to the female
volunteers who had the highest intakes of this nutrient. The vitamin K intake
of men participating in the study did not seem to be related to their bone
mineral density at the same two skeletal points (February 2003 American
Journal of Clinical Nutrition, vol. 77, pp. 512-516).
Scientists at the ARS Jean Mayer
USDA Human Nutrition Research Center on Aging at Tufts University, Boston,
Mass., did the analysis on data from 2,591 Framingham volunteers aged 29 to 86.
Further studies may help explain
why low vitamin K intake and low bone mineral density correlated in women but
not in men. This disparity is especially puzzling because of earlier work which
linked low vitamin K intake to increased risk of hip and spine fractures in
both sexes.
Good sources of vitamin K include
green leafy vegetables and vegetable-based oils and spreads.
For more information, contact
Sarah L. Booth, (617) 556-3231; ARS
Jean Mayer USDA Human Nutrition Research
Center on Aging at Tufts University, Boston, MA
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Radio waves show new promise as a
powerful way to zap bacteria in fruit juice. Using RFEF, or radio frequency
electric fields, as a pasteurization technique isn't a new idea. However, ARS
scientists at the Eastern Regional Research Center, Wyndmoor, Pa., may be the
first to successfully inactivate a bacterium in fruit juice using radio waves
and moderate heat.
For their experiments, the
scientists introduced--into apple juice--a harmless form of Escherichia
coli known as E. coli K12. This microbe mimics the behavior of its
pathogenic foodborne cousin, E. coli O157:H7. They reduced the E.
coli K12 by 99.9 percent by exposing the juice to radio frequencies and
moderate heat of about 122 degrees F. The researchers expect that, with further
development, the treatment will meet the required 99.999 percent kill rate that
today's heat pasteurization provides.
Processors of fruit juices,
vegetable juices, and liquid egg products could benefit from a pasteurization
treatment that doesn't change product flavor or nutritional value.
For more information, contact
David J. Geveke, (215) 233-6507;
USDA-ARS Eastern Regional Research
Center, Wyndmoor, PA
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Vitamin A can help our immune
systems fight certain kinds of infections, like those caused by some food-borne
pathogens. But scientists have not yet determined why this essential nutrient
may be less helpful in combating other pathogens, such as those that cause some
types of pneumonia.
ARS research aimed at helping solve
that puzzle may, in turn, yield better ways to capitalize on the ability of
vitamin A-rich foods to boost the immune system.
At the ARS Western Human Nutrition
Research Center, Davis, Calif., scientists are delineating vitamin A's
influence on the types and amounts of beneficial cells and compounds that the
immune system produces in response to attack. In an early experiment, the
researchers supplied animal immune cells with a form of vitamin A called
9-cis retinoic acid, and exposed the cells to a simulated attack.
This work showed--for the first
time--that more of the immune cells quickly evolved into what are known as T-2
helper cells than into T-1 helper cells.
The difference is important because
T-2 helper cells apparently are more proficient in fighting some pathogens than
others. In humans, that difference could strongly affect how quickly the body
is able to overcome a particular pathogen.
The researchers used mouse immune
cells for these petri dish tests, but they now plan to repeat the tests with
laboratory mice--not just their cells. Studies with healthy adult volunteers
may follow.
Foods that provide vitamin A
include beef, chicken, turkey, sweet potatoes, spinach, and tomato products.
For more information, contact
Charles B. Stephensen, (530)
754-9266; USDA-ARS Western Human Nutrition
Research Center, Davis, CA
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Current recommendations for the
number of calories that healthy women need for everyday life are based, in
part, on research from the ARS Children's Nutrition Research Center at Baylor
College of Medicine, Houston, Texas.
In the March 2003 American
Journal of Clinical Nutrition (vol. 77, pp. 630-638), scientists describe
an investigation to fine-tune women's calorie requirements. The variability in
total energy expended by the 116 female volunteers underscored the need to
include at least four different levels of physical activity, ranging from
sedentary to very active. Previous national recommendations were set for only a
light-to-moderate activity level.
The researchers used a novel,
stable-isotope method to measure volunteers' total energy expenditure over a
2-week period.
The research is a key starting
point for more precisely determining the calorie needs of women during
pregnancy and throughout breast-feeding. That should help ensure healthy
weights for new moms and their infants.
For more information, contact
Nancy F. Butte, (713) 798-7179;
USDA-ARS Children's Nutrition Research
Center at Baylor College of Medicine, Houston, TX
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Watermelon rind, an old-time
favorite for pickling, contains an important natural compound called
citrulline. ARS scientists who were comparing the citrulline content of the
sweet, juicy flesh of commercially grown watermelon determined that the rind is
also a good source of this biochemical.
Citrulline is an amino acid that
the body makes from food.
One of citrulline's key roles is to
create another amino acid, arginine. Some people are deficient in arginine. A
watermelon-rind-based extract or dietary supplement might address this
deficiency.
Scientists at the ARS Natural
Products Utilization Research Unit, Oxford, Miss., and the ARS South Central
Agricultural Research Laboratory, Lane, Okla., conducted the citrulline
analyses.
For more information, contact
Agnes M. Rimando, (662)
915-1037; USDA-ARS
Natural
Products Utilization Research Unit, Oxford, MS, or
Penelope Perkins-Veazie, (580)
889-7395; USDA-ARS South Central Agricultural
Research Laboratory, Lane, OK
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Soybeans’ iron, in the form of
ferritin, may be more available for our bodies to use than was previously
thought. If that preliminary research result holds true in further studies, it
could increase soy’s value as an iron source, to the benefit of the 30
percent of the world's population that, is deficient in this essential
nutrient.
ARS scientists have investigated
the topic since 1994. More recently, agency researchers grew high-ferritin,
Tokyo variety soybeans with a naturally occurring, trackable form of ferritin
inside. They provided the soybeans for a new, 28-day nutrition study led by
investigators at Pennsylvania State University and the Children’s Hospital
Oakland (Calif.) Research Institute.
The 18 female volunteers, aged 19
to 23, who participated in the test were each slightly deficient in iron. The
women ate muffins made with flour from the Tokyo soybeans, had their iron
levels tested 14 days later, then repeated the procedure with soy broth.
The rate of iron absorption
averaged about 27 percent. That's in contrast to the 5 to 10 percent that the
scientists had expected, based on previous results from human volunteers
(January 2003 American Journal of Clinical Nutrition, vol. 77, pp.
180-184). Their analyses will reveal how much of the absorbed iron was in the
form of ferritin.
For more information, contact
Ross M. Welch, (607) 255-5434; USDA-ARS
U.S. Plant, Soil and
Nutrition Laboratory, Ithaca, NY
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A California-based study provides
new and important evidence that healthy men vary in their natural ability to
convert beta-carotene into vitamin A. Scientists at the ARS Western Human
Nutrition Research Center and the University of California at Davis conducted
the investigation with 11 male volunteers, aged 25 to 40.
The study was a follow-up to an
earlier ARS test that had shown surprising differences in the capacity of
female volunteers to use beta-carotene as a precursor of vitamin A, an
essential nutrient.
At prescribed intervals throughout
the 7-week study, the men were fed trackable forms of beta-carotene at
breakfast. In the American Journal of Clinical Nutrition (May 2002, vol.
75, pp. 900-907) the researchers report that the men's absorption of
beta-carotene ranged from 0 to 8 percent of the dose. In turn, conversion of
the beta-carotene to vitamin A ranged from undetectable to 75 percent of the
absorbed dose.
Conversion of beta-carotene to
vitamin A is likely a gene-linked trait. New discoveries about the interaction
of beta-carotene and our genes could lead to customized recommended daily
intakes.
For more information, contact
Betty J. Burri, (530) 752-4748;
USDA-ARS Western Human Nutrition Research
Center, Davis, CA
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