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Food & Nutrition Research Briefs, October 2008
The effect of snacking on teenagers' dietary intakes of recommended
nutrients and MyPyramid food groups has been examined, and the findings are
both positive and negative. After analyzing the eating habits of more than
4,000 teenagers surveyed nationwide, Agricultural Research Service (ARS)
scientists found that 90 percent reported eating one or more snacks in a day.
Overall, snacking was found to enhance the intake of some MyPyramid food
groups, but it also contributed to the intake of excess discretionary calories
as added sugars and fats. Among the highest snackersthose who consumed
four or more snacks in a dayboth boys and girls ate more than twice as
much fruit as their non-snacking peers. Even so, almost three-quarters of those
eating relatively high amounts of fruit failed to meet their MyPyramid
recommendation to consume 1.5 to 2.5 cups of fruit daily, depending on age,
gender and activity level.
Details
Scientific contact:
Rhonda
S. Sebastian, (301) 504-0343, ARS
Beltsville
Human Nutrition Research Center, Beltsville, Md.
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Teen snacking increases the chances of meeting
some MyPyramid recommendations, but also the chances of eating more added
sugars and fats. Get a customized food guide at MyPyramid.gov. Illustration
courtesy of Microsoft Office clipart.
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New research found that the risk of hip fractures
isn't reduced by taking calcium supplements. Graphic courtesy of Microsoft
clipart.
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People, especially the elderly, may reach for calcium supplements in hopes
of protecting themselves against bone fractures in case of a fall. But a recent
analysis of several studies found no reduction in risk of hip fracture with
calcium supplementation. Among the studies that met the researchers' screening
criteria, seven included a total of 170,991 women with nearly 3,000 hip
fractures. Five of the studies included a total of 68,606 men with 214 hip
fractures. Pooled results from those studies suggest that calcium intake is not
appreciably associated with hip fracture risk in women or men. That means that
the researchers did not find that a higher calcium intake reduced the incidence
of hip fractures. The analysis was supported in part by the Agricultural
Research Service (ARS).
Details
Scientific contact:
Bess
Dawson-Hughes, (617) 556-3066,
Jean
Mayer USDA Human Nutrition Research Center on Aging, Boston, Mass.
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The preparation of a potato can have a big impact on its mineral content,
Agricultural Research Service (ARS) scientists have reported. Cubing potatoes
can reduce boiling time, but it also reduces mineral content by as much as 75
percent. This could be a good cooking strategy for potato fans hoping to reduce
potassium intake, such as dialysis patients. But individuals who want to get
the highest nutritional bang for their buck would be better off boiling their
potatoes whole. The effects of leaching the potatoesletting them soak in
water overnightwere also examined. Results showed that leaching had no
significant impact on potassium reduction, in contrast with conventional
wisdom.
Details
Scientific contact:
Shelley
Jansky, (608) 262-8324, ARS
Vegetable
Crops Research Unit, Madison, Wis.
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New research has found that cubing potatoes before
boiling them can reduce the mineral content by as much as 75 percent. Photo
courtesy of USDA.
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Strawberries.
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Agricultural Research Service (ARS) scientists have assessed the human
body's capacity for absorbing certain antioxidant compounds in strawberries,
and have found that the absorption of one key beneficial plant chemical was not
"maxed out" as volunteers ate more of this popular fruit. Foods high
in antioxidants may be excellent sources of healthful compounds, and
researchers are striving to learn more about their ability to be absorbed and
utilized within the human body. The study showed that the human body is capable
of assimilating more anthocyanin pigments as intakes increase.
Details
Scientific contact:
Janet
Dura-Novotny, (301) 504-8263, Food Components and Health Laboratory, ARS
Beltsville
Human Nutrition Research Center, Beltsville, Md.
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Knowing the preferences of foodborne pathogens such as Escherichia coli
O157:H7 is essential to a successful counterattack on these microbes.
That's why Agricultural Research Service (ARS) microbiologist Maria T. Brandl
and University of California-Berkeley colleague Ronald G. Amundson are
scrutinizing the little-understood ability of E. coli O157:H7 and
Salmonella enterica to contaminate romaine lettuce. In experiments, the
scientists exposed romaine lettuce leaves to E. coli O157:H7. They found
that, after 24 hours, populations of the microbe were 10 times higher on young
leaves than on middle ones. One explanation: The young leaves are a richer
nutritional "hunting ground" for E. coli. They exude about
three times more nitrogen and about 1.5 times more carbon than do the middle
leaves.
Details
Scientific contact:
Maria
Brandl, (510) 559-5885, Produce Safety and Microbiology Research Unit,
ARS
Western Regional Research Center, Albany, Calif.
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ARS researchers have found that younger romaine
leaves may be nutritionally richer for E. coli bacteria, a finding that
could lead to new ways to protect romaine and other leafy greens from harmful
organisms.
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Peanuts.
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Fat-free peanut flour, whole peanuts and peanut oil all may have
cardio-protective properties, results from a new animal study by Agricultural
Research Service (ARS) scientists suggest. For the study, male hamsters were
randomly divided into four groups. Each group of nearly 20 hamsters was fed one
of four different diets, all of which were high-fat and high-cholesterol. For
three of the four test diets, equivalent amounts of food components were
substituted with fat-free peanut flour, peanut oil or peanuts without skins.
The fourth diet contained no peanut product. Compared to hamsters in the group
that ate no peanut products, those in each of the three groups that did eat
peanut products were found to have significantly lower total cholesterol and
LDL "bad" cholesterol. Also positive, HDL "good"
cholesterol levels held steady.
Details
Scientific contact:
Timothy
H. Sanders, (919) 515-6312, ARS
Market
Quality and Handling Research Unit, Raleigh, N.C.
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Agricultural Research Service (ARS) scientists have developed a hide-washing
tool that has significantly improved the safety of U.S. beef while saving the
beef industry millions of dollars each year. An estimated 50 percent of U.S.
feedlot-raised beef cattle undergo the washing treatment, which has reduced the
national incidence of pathogenic Escherichia coli in ground beef samples
by about 43 percent.
Details
Scientific contact:
Terrance
M. Arthur, (402) 762-4227, Meat Safety and Quality Research Unit, ARS
Roman
L. Hruska U.S. Meat Animal Research Center, Clay Center, Neb.
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A chemical hide wash is one of the best ways for
meat processors to reduce the risk of E. coli contamination.
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ARS researchers are looking at varying abilities
of bacteria strains to grow on vegetables such as this broccoli sprout, where
green fluorescence indicates the presence of Listeria monocytogenes
three days after innoculation in the lab.
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An Agricultural Research Service (ARS) researcher is working to pinpoint
genes responsible for the widely varying ability of eight different Listeria
strains to successfully colonize the hair-thin strands, called root hairs,
of alfalfa sprouts. She's also interested in studying, and disabling, genes
that help some Listeria colonies resist being washed off leaves of
produce such as cabbage by water.
Details
Scientific contact:
Lisa A.
Gorski, (510) 559-6046, Produce Safety and Microbiology Research Unit,
ARS
Western Regional Research Center, Albany, Calif.
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An experimental treatment from Agricultural Research Service (ARS)
scientists that is based on cold plasma could one day help protect some fresh
produce from potentially dangerous microbes such as Salmonella, Listeria
and Escherichia coli O157:H7. Cold plasma is generated when some
form of concentrated energyin this case, electricityis introduced
into a gas until free electrons are torn from the gas' atoms. This
plasma-forming process is related to the technology used to create plasma for
computer chips. But in addition to increasing conductivity, the process of
turning gas into plasma has an antimicrobial effect. The ARS researchers aren't
the first to harness this technology for food safety purposes, but their method
of production has the potential for increased efficiency and lower costs when
applied at a larger scale.
Details
Scientific contact:
Brendan
A. Niemira, (215) 836-3784, Microbial Food Safety Research Unit,
ARS
Eastern Regional Research Center, Wyndmoor, Penn.
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An experimental treatment that relies on cold
plasma, which is created by introducing electricity into a gas until free
electrons are liberated, may one day keep fresh produce like apples and almonds
safe from potentially harmful bacteria such as Salmonella, Listeria and
E. coli. Photo courtesy of Paul Pierlott.
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New variety Gulfcrimson is an early summertime
peach. Photo courtesy of Tom Beckman, USDA/ARS.
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A new peach variety that requires less winter chilling will give growers in
the southeastern lower coastal plain an edgeand consumers a more reliable
supplyof early summertime peaches.
The new variety, called Gulfcrimson, was developed by the Agricultural
Research Service (ARS) in cooperation with the University of Georgia and the
University of Florida. Gulfcrimson only requires 400 hours of chilling to
flower and set fruit. By comparison, a commonly grown variety called June Gold
requires 650 hours of chilling. However, in years of insufficient winter
chilling, June Gold can't reliably set fruit, resulting in reduced crops for
growers.
Details
Scientific contact:
Thomas
G. Beckman, (478) 956-6436, ARS
Southeast
Fruit and Tree Nut Research Lab, Byron, Ga.
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