Preliminary findings suggest that drinking lots of non-diet sodas coupled
with eating few leafy greens, nuts and whole grains may compromise bone
building and maintenance, according to an ARS study. It's a dietary combination
quite common among U.S. youths. Drinking 57 ounces--close to 5 cans--of sugary
sodas each day for weeks at a stretch upset the calcium and phosphorus balances
of the 11 young men in the study. And the effect on these bone minerals was
greatest while the experimental diets were low in magnesium, the researchers
reported in the Proceedings of the North Dakota Academy of Science (vol
51, p 212).
Non-diet sodas are a major source of fructose in the U.S. diet. Leafy
greens, nuts and whole grains are rich in magnesium. But 38 percent of U.S.
males over age 19--and 39 percent of male teens--get less than 75 percent of
the recommended magnesium intake through foods, according to recent USDA
consumption data. Statistics for females are worse: 46 percent over age 19 and
60 percent of teens. Males drink more regular soft drinks, however, averaging
close to one 12-ounce can daily. Teenage males average about 20 ounces a day.
And some regularly consume as much as the study volunteers.
All that soda put the volunteers "in the red" for phosphorus. They
excreted more than they absorbed--both when they got adequate magnesium and
when they got half the Recommended Dietary Allowance (RDA). Besides being a
major bone mineral, phosphorus is central to cells' energy production system
and is integral to DNA and its sister RNA. The volunteers' calcium balance
remained positive but dropped, especially during the low-magnesium period.
For more information, contact
Forrest H. Nielsen or
David B. Milne, (701) 795-8353,
Grand Forks Human Nutrition Research
Center, Grand Forks, ND.
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Mild doses of synthetic female hormones, estrogen and progestin, may prevent
bone loss in young women who have stopped menstruating because of eating
disorders or excessive exercise, a study suggests. This condition, known as
hypothalmic amenorrhea, can be especially risky for teenage girls whose bones
are still developing because it increases the risk of osteoporosis later in
life.
In an attempt to reverse bone loss in these cases, researchers with Baylor
College of Medicine and ARS's Children's Nutrition Research Center, both in
Houston, collaborated on a year-long study of 24 young women, ages 14 to 28.
Under the guidance of the Baylor physician, the women were divided into three
treatments: a combination estrogen and progestin tablet for 21 of the 28 days
in the cycle; a progesterone formulation for the last 12 days of the cycle; or
a look-alike placebo. Their bone density was measured at the ARS center before,
during and after treatment.
After a year, the women taking the estrogen and progestin preparation had
significantly more bone mineral in their total skeletons and in the lower spine
compared to the other two groups. The researchers believe that the treatment
mimics the hormonal activity of the normal menstrual cycle and helps protect
the bones against mineral loss until other medical care can restore the
patients' general health--and natural menstrual cycle.
This research was published in the American Journal of Obstetrics and
Gynecology (vol. 176, pp. 1017-1025). Since the number of women studied was
very small, further study is needed. But if the results prove consistent,
physicians will have a new path to explore in treating bone loss for the five
to ten percent of American women and girls who suffer from eating disorders.
For more information, contact Albert
C. Hergenroeder, (713) 770-3658, Dept. Pediatrics, Baylor College of
Medicine; or Kenneth J. Ellis, (713)
798-7025, Children's Nutrition Research
Center, Houston,TX.
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ARS scientists are finding better ways to mine ancient herbs, like St.
John's wort and wormwood, for their curing compounds and for safer natural
pesticides. The agency recently established a Natural Products Utilization
Research Unit, based in Oxford, Mississippi. Among the research team's
successes are improved extraction techniques for annual wormwood to obtain
artemisinin, a potent malaria-fighting drug. The team also is improving
extraction techniques for St. John's wort. This plant yields mood-enhancing
compounds, according to studies published in medical journals.
The researchers find better extraction methods by studying plant physiology.
In the case of wormwood, the ARS team found that the tiny balloon-like glands
on the plant's leaves are filled with artemisinin. In nature, the glands serve
as built-in biopesticide applicators. The glands rupture during insect attacks,
oozing micro-doses of artemisinin and other compounds that repel the pests.
In studies with St. John's wort, the scientists are improving extraction
methods for hypericin, which many scientists believe is responsible for the
plant's benefits. The usual approach is to crush the plant, but ARS research
suggests this releases enzymes that can destroy the hypericin.
For more information, contact Stephen O.
Duke, (601) 232-1036, USDA-ARS Natural Products
Utilization Research Unit, Oxford, MS.
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An expectant mother's chances of delivering a healthy, normal-weight baby
may increase in the future, thanks to a promising new technique--bioimpedance
spectroscopy--for monitoring water- weight gain during pregnancy. Physicians
have known for more than four decades that moderate water accumulation during
pregnancy is a strong indicator of proper fetal growth.
Scientists with ARS, the University of California at Berkeley, and Xitron
Technologies, Inc., San Diego, Calif., showed that bioimpedance measurements
correlate significantly with infant birth weight. The researchers measured
water-weight gain of 10 women before pregnancy, at intervals throughout
pregnancy, and after delivery. The measurements are painless and take less than
two minutes to perform. They involve sending a harmless current between
electrodes positioned on the hand and foot, as described in the Journal of
Applied Physiology (vol. 78, pp. 1037-1042).
The ARS-led investigation is likely the first to show that bioimpedance
spectroscopy may offer a safe, accurate and inexpensive way for physicians to
detect subnormal water-weight gains in time to help their patients take
corrective action. Low-birth-weight babies--weighing less than 5.5 pounds at
birth--have an even greater risk of early health complications than premature
babies. An expectant mother who does not eat properly, exercises too
vigorously, takes diuretics or abuses drugs, for example, may deliver an
underweight infant.
For more information, contact Marta D. Van Loan, (415) 556-5729,
Western Human Nutrition
Research Center, Presidio of San Francisco, CA.
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Vitamin D status is better for elderly men and women in the general
population than for elderly hospital patients. But this first population-based
study of vitamin D suggests inadequacy is an important public health problem in
older Americans. Vitamin D is essential for healthy bones and teeth and helps
prevent osteoporosis.
Researchers with USDA's Human Nutrition Research Center on Aging at Tufts
and the Framingham, Mass., Heart Study conducted the study with 759 free-living
volunteers, age 67 to 95. About 15 percent of the women and 6 percent of the
men had low blood levels of 25- hydroxyvitamin D--the major circulating form of
vitamin D and the most sensitive measure of D status. About 4 percent of the
women and 2 percent of the men were deficient, the researchers reported in the
American Journal of Clinical Nutrition (vol. 66, pp. 929-936).
Milk is fortified with the vitamin as are some breakfast cereals. Fatty
fish, egg yolks, liver, cheese and butter are naturally rich sources. And
sunlight stimulates skin to manufacture the vitamin. The study data confirm the
importance of eating foods rich in vitamin D and exposing skin to sunlight.
Participants' blood levels of D rose in step with intakes, plateauing only
for men after daily intakes reached 400 International Units--twice the
Recommended Dietary Allowance. Two-thirds of the volunteers drank less than 8
ounces of milk daily, which would supply half the RDA. Vitamin D supplements
were a significant factor for the women's status and nearly so for the men's.
Only 25 percent of the women and 20 percent of the men took vitamin D
supplements. Vitamin D levels were highest in late summer--after months of
long, sunny days--and lowest in late winter. Low D status was inversely
associated with time outdoors. The study was funded by the National Institutes
of Health and ARS.
For more information, contact Paul
F. Jacques, (617) 556-3320, Jean Mayer
USDA Human Nutrition Research Center on Aging at Tufts, Boston, MA.
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Tender, affordable meats with less fat could come from technology that uses
shock waves to improve the texture of everything from lamb chops to steaks.
Underwater shock waves from a high-energy explosive charge tenderize meat with
pressures as high as 25,000 pounds per square inch. Known as hydrodyne, the
technology provides an alternative to fat as a source of tenderness. It can
improve tenderness of less tender meat by 50 to 70 percent, well exceeding the
previous goal of 40 percent improvement. Taste tests by ARS scientists showed
it made inexpensive cuts of meat taste like higher-priced ones.
Hydrodyne was invented by a mechanical engineer retired from the Department
of Energy. The technology is being evaluated by ARS scientists familiar with
the meat industry's needs. Together, they are fine-tuning hydrodyne to make it
industry ready. The next step will be training workers in its use.
A prototype at Tenderwave, Inc., in Buena Vista, Virginia, can tenderize 600
pounds of meat at once. A 7,000-pound steel tank filled with water is covered
with an 8-foot-diameter, 5,000-pound steel dome. Large primal cuts of meat,
encased in water- and pressure-resistant wrapping, are lowered into the tank.
Then an explosive charge is set off in the water about 2 feet from the meat.
The tank's dome holds in water that is forced upwards. The ARS scientists will
explore alternatives to explosives for discharge systems.
For more information, contact Morse Solomon, (301) 504-8463,
Meat Science
Research Laboratory, Beltsville, MD;
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Live colon cells isolated from stool samples may soon give physicians a
reliable, noninvasive early warning technique for colorectal cancer. This
disease causes about 14 percent of all cancer- related deaths in the U.S. It
begins as abnormal growths, or polyps, 3 to 5 years before a malignancy
appears. The current noninvasive screening method--which checks for blood in
fecal smears--is plagued with false positives and false negatives. And a true
positive reading means the tumor is fairly advanced.
Instead, a screening method based on subtle changes in the genes and surface
proteins of isolated colon cells could prove far more useful. An ARS chemist
developed the method for isolating live, intact colon cells from the stool. He
then collaborated with a gastroenterologist at Sinai Hospital of Baltimore to
look for markers in these cells. The researchers found that CD44--the tell-tale
marker reported on other types of cancer cells--also appears on the surface of
isolated colon cells. They have also detected mutated genes in these cells,
indicating malignancy. They discussed the potential of this screening technique
in an editorial in Gastroenterology (vol. 114, pp. 1333- 1334).
The editorial accompanies a report by Japanese researchers (pp. 1196-1205)
who isolated colon cells and found variants of the CD44 marker that might make
sensitive indicators of precancerous conditions. British researchers reported a
strong correlation between the amount of DNA in isolated colon cells and the
presence of tumors in Clinical Cancer Research (vol. 4, pp. 337-342) .
That's because rapidly dividing cells contain more DNA.
It's possible that, in five years, stool samples will routinely be analyzed
for an array of tell-tale markers and gene mutations. This technique is already
one of the first molecular biology assays to be evaluated in a clinical
setting, the researchers report.
For more information, contact Padmanabhan P. Nair, (301) 504-8145,
Beltsville Human Nutrition
Research Center, Beltsville, MD; or Sudhir K. Dutta, (410) 601-5392,
Sinai Hospital of
Baltimore, Baltimore, MD.
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New technology could help viruses, bacteria and other environmentally
friendly biopesticides compete with traditional chemical pesticides. ARS
scientists and cooperators in Mexico have produced improved formulations that
feature economy, reliability and user friendliness, according to their report
in the Journal of Economic Entomology (vol. 91, pp. 86-93).
Called microencapsulation, the technology involves mixing microbes with a
matrix-forming material, such as cornstarch that has been heated, or partially
gelatinized, to enable water absorption. When the mixture is added to water and
dried, the microbes become entrapped in tiny protective particles. Resuspended
in water, the particles can be applied to crops using conventional spray
equipment.
Until now it's been difficult to market encapsulated biopesticides because
there was no single formulation appropriate for different crops and
field-spraying equipment. The amount of ingredients such as sun protectants
added to boost a formulation's effectiveness depended on how much water was
needed for the mix. With the new technology, these ingredients--called
adjuvants--are mixed into formulations as they are manufactured. The adjuvants
are uniformly bonded with starch and the biopesticide, remaining stable
throughout conventional tank mixing and application.
For more information, contact Michael R. McGuire, (309) 681- 6595,
National Center for Agricultural
Utilization Research, Peoria, IL;
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An enzyme in horseradish could make it easier to produce anti-cancer drugs,
saving time and money. An ARS researcher devised a one-step method, using the
enzyme horseradish peroxidase, to make cancer drugs known as chlorins.
Currently, chlorins are made in a costly multi-step process.
All plants use a form of peroxidase to make cell walls, but the horseradish
version is extremely easy to extract. The researcher made chlorins by combining
the horseradish enzyme and a chemical cousin of chlorophyll. Plants use
chlorophyll to turn light energy into food. But scientists doing research
studies frequently turn to chlorophyll's cheap, easier-to-use synthetic cousin,
deuteroporphyrin IX. The method is published in the Archives of Biochemistry
and Biophysics (vol. 351, pp. 27-34).
Now, the University of Mississippi School of Pharmacy will test human cell
cultures to ensure chlorins made this way are still effective photodynamic
drugs. Photodynamic compounds kill tumors when exposed to red light from tiny
lasers. First, the drug is injected and carried through the body by blood
proteins. Because cancer cells grow 10 times faster than healthy cells, they
take in much more of the drug than healthy cells. After a few days, a physician
shines a red laser light on the tumor. Nearby healthy cells--transparent to the
red light--are unaffected. But the chlorin molecules in the tumor cells are
energized by red light and produce free radical oxygen molecules that destroy
them.
For more information, contact Franck E.
Dayan, (601) 232-1036, USDA-ARS Natural Products
Utilization Research Unit, Oxford, MS;
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NuSun, a healthful vegetable oil from new sunflower hybrids, is designed to
make foods taste better and stay fresh longer. The new oil is low in saturated
fat but high in the monounsaturated fat, oleic acid. Some studies indicate that
a moderately low-fat diet with a high oleic acid content lowers serum
cholesterol and the risk of coronary heart disease. With 60 to 75 percent oleic
acid, NuSun has several times more than traditional sunflower oil and less than
half as much of the polyunsaturated fat, linoleic acid.
However, linoleic acid content is still high enough for desired flavor in
fried foods. In sensory panel evaluations, tortilla chips fried in NuSun oil
stayed fresh tasting longer than chips fried in commercial sunflower oil. NuSun
holds up well in frying vats even without hydrogenation, a process normally
required to protect oils from flavor deterioration.
This year, growers planted 100,000 acres of NuSun hybrids. The new
sunflowers could spur a doubling of U.S. oilseed sunflower acreage from its
present 2.2 million acres by 2001.
For more information, contact
Jerry F. Miller, (701)
239-1321, Red River Valley
Agricultural Research Center, Fargo, ND; or
Kathleen A. Warner, (309) 681-
6555, National Center for Agricultural
Utilization Research, Peoria, IL.
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Want to know how much folate (folic acid) you're getting from foods, now
that millers and bakers are fortifying breads, flour, cornmeal, rice, pasta and
other enriched grain products with the vitamin? Just take the World Wide Web to
the home page of the Agricultural Research Service's Nutrient Data Laboratory:
http://www.nal.usda.gov/fnic/foodcomp. There, you'll find the latest
update of the main source of food composition data in the United States,
technically known as Nutrient Database for Standard Reference, Release 12, or
SR-12 for short.
The database has values for as many as 81 nutrients in 6,000 foods among 22
food groups. It's the only such database worldwide that's free. Some 8,000
visitors access the web site each month. Many arrive there via one of 400 web
sites around the world with links to the USDA nutrient database.
SR-12 includes newly revised folate values for enriched grain products and
foods in which they are ingredients. Also new are selenium values for many food
items. An essential nutrient in the body's antioxidant functions, selenium has
gained attention for its purported anti-cancer properties.
Beginning this year, the database is undergoing a major update. Laboratory
personnel and researchers with the National Institutes of Health and
agricultural commodity groups are collaborating on a 5-year program to ensure
nutrient data with unprecedented analytical quality for the 1,000 foods that
contribute most to the nation's nutrient intake. The program is expected to
cost $15 million.
For more information, contact Joanne M. Holden, (301) 734-8491,
Nutrient Data Laboratory,
Beltsville Human Nutrition
Research Center, Riverdale, MD.
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CONFERENCE
ANNOUNCEMENT |
What We Eat in America: Research and
Results |
Highlights of the 1994-96 nationwide Continuing
Survey of Food Intakes by Individuals and Diet and Health Knowledge Survey will
be presented at a 2-day conference, September 14-15, at the Double Tree Hotel,
Rockville, MD. The conference--free of charge--will include a session on use of
the CD-Rom for survey results and another on the USDA's food coding, nutrient
and Pyramid servings databases. Program and registration information are listed
on the Food Surveys Research Group web site:
http://www.barc.usda.gov/foodsurvey/home.htm. Or, contact Rhonda
Sebastian, (301) 734-8482, rsebastian@rbhnrc.usda.gov |
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