New sweetpotatoes now being developed
by ARS scientists have less sugar and soak up less oil than traditional
varieties, making them perfect for great-tasting and nutritious chips
and french fries. Both preparations absorb less oil because they have
a higher percentage of dry matter. This means they're denser than traditional
varieties, so they're crispier and contain less fat. And they have plenty
of beta carotene and other nutrients.
For the past eight years, ARS scientists
and cooperators at Clemson University have used conventional breeding
to develop medium- to light-orange, yellow, or cream-colored sweetpotato
breeding lines for new uses. One scientist has been testing them in a
small-scale, chip-making kitchen in her ARS laboratory. She is looking
for a commercial cooperator to produce and test the fries on a larger
scale. If they catch on, consumers could benefit from the extra nutrients.
Unlike popular sweet, orange-fleshed U.S.
varieties, the new sweetpotatoes resemble those eaten in the tropics and
favored by U.S. consumers from Asia, Africa, the Caribbean and South America.
The sweetpotatoes grow and produce well in the South and require fewer
pesticides because they're resistant to key sweetpotato pests.
For more information, contact Janice
R. Bohac, (843) 556-0840, U.S.
Vegetable Laboratory, Charleston, SC
Recurring rumors that commercial peanut
butters contain trans fatswhich appear to increase risk of cardiovascular
diseasehave no basis in fact, a new study shows. The rumors no doubt
started because small amounts of hydrogenated vegetable oils are added
to commercial peanut buttersat 1 to 2 percent of total weightto
prevent the peanut oil from separating out. And the hydrogenation process
can generate the formation of trans fatty acids in oils.
To see if the rumors had any validity,
an ARS researcher prepared 11 brands of peanut butter, including major
store brands and "natural" brands, for analysis by a commercial
laboratory. He also sent paste freshly prepared from roasted peanuts for
comparison. The laboratory found no detectable trans fats in any of the
samples, with a detection limit of 0.01 percent of the sample weight,
the researcher reported in the Journal of Agricultural and Food Chemistry,
2001 (vol. 49, pp. 2349-2351).
That means that a 32-gram serving of any
of the 11 brands could contain from zero to a little over three-thousandths
(0.0032) of a gram of trans fats without being detected. While current
regulations don't require food labels to disclose trans fat levels, they
do require disclosure of saturated fat levels at or above five-tenths
(0.5) of a gram. For comparison, that's 156 times higher than this study's
detection limit for trans fats.
By contrast, peanut butter has plenty
of unsaturated fatty acids. The most abundant is oleic acid, the monounsaturated
fat believed to be good for the cardiovascular system. In this analysis,
oleic acid levels ranged from 19 percent of total weight in one private-label
brand to 27 percent in one "natural" type. Palmitic acid, the
most abundant saturated fatty acid, weighed in at about 5 percent among
For more information, contact Timothy
H. Sanders, (919) 515-6312, Market
Quality and Handling Research Unit, Raleigh, NC
A relatively benign influenza virus has
mutated into a nasty pathogen in laboratory mice that were raised on a
diet deficient in seleniuma potent antioxidant. And the mutations
persisted when the virus was transferred into mice fed ample selenium,
causing a much more severe case of flu than the original strain.
Seven years ago, a lesser known virusa
strain of coxsackiemutated from "Jekyll" to "Hyde"
in selenium-deficient mice. It happened again in mice deficient in vitamin
Eanother antioxidant. Now, the same researchers from the University
of North Carolina and the Agricultural Research Service, along with new
colleagues at the Nestle Research Center in Switzerland, have seen it
happen in human influenza virusa strain isolated in Bangkok in 1979.
The findings suggest that many RNA viruses may be susceptible to nutritionally
induced oxidative damage, the researchers reported in the FASEB Journal
Express, 2001 (DOI 01-0115) online at: http://www.fasebj.org.
The phenomenon has global implications.
While Americans generally get the recommended dietary levels of selenium,
there are pockets of selenium deficiency around the world that might be
generating harmful mutations in a number of viruses. Such mutations may
also occur in areas where diets are low or devoid of other antioxidants.
And viruses know no boundaries.
In the influenza virus, 29 bases in a
normally stable section of the viral genome had mutated in the selenium-deficient
mice. By contrast, there were no mutations in these same bases from selenium-adequate
mice. It shows that the host's nutrition can have considerable influence
on the virulence of viral pathogens. And that virulence persists in well-nourished
animals and, presumably, people.
The discovery points to the importance
of antioxidant protection against viral diseases. Selenium is a critical
part of a major antioxidant enzyme that humans and animals produce to
protect delicate cellular components against damage from oxygen free radicals.
The selenium level in the study's deficient diet was one-sixtieth that
of the adequate diet. Good sources of this essential element include Brazil
nuts, whole-grain products and meat.
For more information, contact Orville
A. Levander, (301) 504-8504, Nutrient
Requirements and Functions Laboratory, Beltsville, MD; or Melinda
A. Beck, (919) 966-6809, University of North Carolina, Departments
of Nutrition and Pediatrics, Chapel Hill, NC
Children in the mid-South are eating more
"heart healthy" these days. But that won't help unless they
learn to balance food consumption and physical activity. According to
new findings from the ongoing Bogalusa (Louisiana) Heart Study, kids are
losing ground in keeping extra pounds off.
Researchers at ARS' Children's Nutrition
Research Center in Houston and at Tulane University in New Orleans have
been monitoring the height, weight, eating habits and subsequent heart
disease risk of 10-year-old children in Bogalusa since 1973. While the
amount of total fat, saturated fat and cholesterol in their diets has
decreased, kids today are heavier by nearly 5 poundswith no change
in average heightand more of them are obese, researchers reported
in the American Journal of Epidemiology, 2001 (vol. 153, pp. 969-77).
Despite the rise in body weight, the number
of calories that 10-year-olds consume has held fairly steady over the
past 20 years, ranging from about 2,000 to 2,200 calories each day. However,
the source of those calories has changed significantly. In the 1990s,
children consumed more calories from carbohydrates like fruit, fruit juice,
beverages such as sodas, iced tea, coffee and koolaid, and snacks, but
fewer from animal fats, candy, eggs and desserts.
Still, over 70 percent of children nationally
consume more than the recommended amounts of total and saturated fat.
Suggested is no more than 30 percent of calories from fat, including no
more than 10 percent of total calories from saturated fat for all Americans
over age two.
Physical inactivity could contribute to
the higher weight. But researchers also suspect that the dietary assessment
tools used in the study might have missed small increases in daily caloric
intake that can add up to significant weight gain over time. All it takes
is an extra 48 calories a day to gain five pounds a year. Forty-eight
calories is about a one-half cup of soda or juice or seven potato chips.
For more information, contact Theresa
Nicklas, (713) 798-7000, Children's
Nutrition Research Center at Baylor College of Medicine, Houston,
Ticks that transmit Lyme disease have
been dropping like flies in parts of Maryland where deer snack on corn
in a device developed by ARS scientists in Kerrville, Texas. To reach
the corn, deer brush their heads and necks against paint rollers filled
with amitraza pesticide deadly to ticks but relatively harmless
to beneficial insects and wildlife and approved for livestock. This inventioncalled
the "four poster"offers a tick-control alternative to
spraying insecticides into the environment or reducing deer populations.
Each year, more than 10,000 human cases
of Lyme disease are reported in the United Statesmainly in suburban
areas with an overabundance of white-tailed deer. So, in 1997, the U.S.
Department of Agriculture implemented a five-year project to reduce ticks
in suburban areas of five Northeast states where the incidence of Lyme
disease was highest. The states include Connecticut, Rhode Island, New
York and New Jersey, as well as Maryland.
The project aims to reduce blacklegged tick nymphs by
90 percent after five years at each of the 1,280-acre treatment sites.
It's the tick's tiny, nymph stage that transmits the Lyme disease bacterium,
Borrelia burgdorferi, to most people.
In 2000, two years after the feeders were
deployed in Maryland, blacklegged tick nymphs had dropped 59 to 71 percent
at the three treatment sites. The ARS entomologist anticipates reductions
of at least 75 percent after two more years. While tick nymphs are most
dangerous to humans, the four-poster feeder targets female adultsbefore
they can lay the eggs that will hatch into larvae that develop into nymphs.
Generally, the larvae pick up the Lyme disease pathogen from feeding on
infected mice or other small animals.
For more information, contact J. Mathews
Pound, (830) 792-0342, U.S. Livestock Insects Research Laboratory, Kerrville,
TX; email@example.com, or John
F. Carroll, (301) 504-9017, Parasite
Biology, Epidemiology and Systematics Laboratory, Beltsville, MD
Native Americans have denser bones than
Caucasians, even though they don't eat many dairy foods. Scientists have
cited genetic differences as an explanation for low bone fracture rates
among the Navajos, the largest tribe of North American Indians. But environmental
and cultural differences also may play a role.
An ARS nutrition researcher is collaborating
with investigators at Utah State University to determine how overall mineral
intake is related to bone health and other conditions in Navajos living
on a reservation that lies in Utah, Arizona and New Mexico. They found
that the total intake of minerals important for strong bones is much closer
to recommended levels than the diet surveys suggest. And this may partially
explain low fracture rates.
The ARS researcher analyzed more than
100 water samples for mineral content and found that the average water
intake of two liters a day can provide up to 212 milligrams of calcium,
150 mg of magnesium and 8 mg of zinc, the researcher reported in Toxicology,
2000 (vol. 149, pp. 143-148). Navajos on this reservation get their water
from wells, springs and taps and store it in barrels.
The USU researcher analyzed juniper ash
and found it rich in calcium, magnesium and zincminerals that help
build strong bonesthe researcher reported in the Journal of the
American Dietetic Association, 1998 (vol. 98, pp. 187-192, 1998).
Navajos burn juniper branches, grind the ash into a powder and add it
to breads and traditional corn dishes. The extra minerals in their drinking
water and foods may partially explain their low fracture rates.
In older people, fractures of the hip,
spine and other bones result from osteoporosisor "porous bones"characterized
by a decrease in bone density. Nearly 10 million Americans suffer from
osteoporosis, according to the National Institutes of Health. It can be
prevented or delayed by taking several preventive measures, such as exercising,
not smoking, limiting alcohol intake and eating foods that are high in
calcium, magnesium and vitamin D.
For more information, contact Judith
G. Hallfrisch, (301) 504-9061, Diet
and Human Performance Laboratory, Beltsville, MD
New mothers who choose to breast-feed
help not only their babies: They could also be building healthier bones
for themselves, according to a two-year study. Earlier research that questioned
whether breast-feeding is the best option for women at risk for osteoporosis
prompted the new study, published in the Journal of Nutrition,
2000 (vol. 130, pp. 777-783).
It showed that, while lactation triggers
bone loss in areas prone to fractures later in lifesuch as the hip,
wrist, and spinethe lost bone was completely replaced with fresh,
new bone within two years of delivery. This bone-loss/recovery cycle,
known as remodeling, provides a breast-feeding mother's body a unique
opportunity to repair tiny flaws, or microfractures, when the replacement
bone is built. Microfractures are thought to contribute to osteoporosis
fractures later in life.
Researchers monitored the bone densities
of 76 new mothers over a period of two years after delivery. Half breast-fed
their infants; the others chose to formula-feed. Bone densities were measured
at regular intervals using a sensitive bone scan called DEXA.
In addition to regaining lost bone, mothers
who had breast-fed for nine months or less were found to have nearly three
percent more bone than right after delivery. Mothers who breast- fed longerbetween
10 and 24 monthswere also gaining more bone, but at a slower rate.
Had the study been longer, this group would probably have shown significant
bone gains as well, the researchers believe.
The study also shows that pregnancy itself
appears to trigger changes in bone structure. The researchers are investigating
these findings in a new study, which monitors pre-pregnancy and postpartum
bone densities to better understand how pregnancy affects maternal bone.
For more information, contact Judy
Hopkinson, (713) 798-7000, Children's
Nutrition Research Center at Baylor College of Medicine, Houston,
Premature infants might benefit from
receiving more of their nutrition by mouth. That's the implication of
a study on the effects of minimal oral feedings on the intestinal growth
of newborn piglets, whose gastrointestinal development and function are
similar to that of human infants.
While preemies must rely on intravenous
feedings to survive, they usually start receiving small amounts of oral
tube feedings within days of life to help stimulate intestinal growth
and development. The new findings suggests that the usual starting point
for these feedings10 to 15 percent of total nutritional needsmight
not be enough to stimulate growth.
The researchers monitored the effect
of varying levels of oral versus intravenous feedings on the piglets'
intestinal growth. They found that the intestinal tissues did not significantly
increase in size, protein content or weightall measures of growthuntil
the amount of total nutrients delivered orally reached 40 percent. Normal
development was achieved at a level of 60 percent, they reported in the
American Journal of Clinical Nutrition, 2000 (vol. 71, pp. 1603-
Because certain nutrients, such as amino
acids, play a key role in intestinal growth, the researchers are now evaluating
whether the mix and amounts of specific nutrients delivered orally also
affects intestinal growth and function. They believe their findings with
piglets could lead to clinical studies that test how increasing the amounts
of oral tube feedings might benefit the intestinal growth of premature
For more information, contact Douglas
G. Burrin, (713) 798-7000, Children's
Nutrition Research Center at Baylor College of Medicine, Houston,
ARS scientists believe they have found
one major source of the foodborne pathogen, Campylobacter: the
fertile chicken egg. Their research ultimately may help reduce or prevent
this bacterium from entering the marketplace.
Historically, possible sources of the
bacteria were thought to be the feed, wild birds, well water, bird fluff
and pads in the cages. Through inoculation studies, scientists showed
that Campylobacter can't survive long in dry conditions, eliminating
bird feathers and hatchery transport paper pads from the list of possible
sources. Other studies showed that feces on the surface of eggs were an
unlikely source of contamination. Thus, attention focused on transmission
of the bacteria in the egg itself.
To learn how each new generation of chicks
is infected with the bacterium, they traveled to Iceland, where poultry
is produced in a closed system. Breeder eggs are obtained from Sweden,
hatched in Iceland and quarantined at rearing farms. It is an integrated
approach with a high degree of control.
By sequencing genetic material called
DNA, a specific gene in Campylobacter was isolated and used as
a marker to identify identical organisms. Evidence shows that the same
Campylobacter isolate was detected in poultry production plants
about 20 miles apart. The only way the organism was able to travel from
one location to the other was in the moist confines of the egg.
For more information, contact Norman
Stern, (706) 546-3516, Poultry
Microbiological Safety Research Unit, Athens, GA