Hormonal differences that might help explain
why African-American girls grow faster and taller than Caucasian girls could
also be stacking the deck in favor of weight gain in adulthood. Researchers
found higher blood levels of a potent growth hormone--free IGF-1--in
African-American girls than in their Caucasian peers. The African-American
girls had correspondingly lower blood levels of two specific binding proteins
that tie up free IGF-1 in the bloodstream, making it inactive.
This raises the question of whether high
levels of free IGF-1 are accelerating growth in African-American girls and
whether these higher levels could be a factor in excessive weight gain if they
persist once growth is complete, the researchers speculated in the Journal
of Pediatrics, 1999 (vol. 135, pp. 296-300).
They designed the study to learn why
African-American girls are more sexually mature, taller and heavier--with more
muscle mass and body fat--than Caucasian girls. It involved 136 healthy
African-American and Caucasian girls of normal weight between the ages of 9 and
17. It's the first study to report ethnic differences involving IGF-1, short
for Insulin-like Growth Factor-1.
The findings suggest that insulin might be
involved in how much free IGF-1 is in circulation in the body. Insulin inhibits
production of one of the binding proteins that inactivate IGF-1. This
connection is significant because healthy, normal-weight African-American
children have higher blood insulin levels than Caucasians. High insulin is
thought to predispose people to adult-onset (Type 2) diabetes. Even if diabetes
doesn't develop, high insulin mightcontribute to high cholesterol, weight
problems and hypertension--all more prevalent among African Americans.
For more information, contact
William Wong, (713) 798-7168,
Children's Nutrition Research Center at
Baylor College of Medicine, Houston, TX
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A fun, fast-paced video game called
"Squire's Quest!" might entice kids to eat more fruits and
vegetables, according to the scientists who are creating and testing it with
1,600 children in Houston elementary schools. The video game is part of an
innovative nutrition-education program developed by research psychologists,
behavioral nutritionists, a health educator and a freelance writer. U.S.
children now eat only about two to three-and-one-half servings of fruit and
vegetables daily, instead of the five to nine servings recommended for optimal
physical and mental growth and development.
Each child playing the video game starts as a
squire and enters into training to become a knight. Knights help to protect an
imaginary kingdom called "Five-A-Lot" from invaders bent on
destroying its fruits and vegetables. As squires earn points toward various
levels of knighthood, they learn about fruits, 100-percent fruit juices, and
veggies.
The game is part of a series of ten 25-minute
classroom sessions in which kids make tasty virtual recipes using fruits and
veggies. Then they set personal goals for making those recipes at home and for
eating at least one more serving of a fruit or vegetable at a specific meal or
snack. The scientists expect to finish analyzing the results of their education
experiment by the end of summer 2000. An evaluation of their school-based
intervention, Gimme 5, appears in Health Education and Behavior, 2000
(vol. 27(1), pp. 96-111).
For more
information, contact Tom Baranowski,
(713) 798-6762, Children's Nutrition
Research Center at Baylor College of Medicine, Houston, TX
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Chances are you'll get more antioxidant
protection from eating fresh fruits and vegetables than from taking natural
product supplements claiming to be potent antioxidants. That's according to
analyses of 46 commercial preparations by the ORAC assay. ORAC--short for
oxygen radical absorbance capacity--measures the ability of a chemical or
biological sample to disarm oxygen free radicals, which can precipitate a
cascade of oxidative damage in body cells. Theory holds that such damage is
behind heart disease, cancer and other diseases of aging. So antioxidant
supplements are gaining popularity.
ARS researchers found the total antioxidant
capacity of 40 berry-based supplements ranged from 16 to 3985 ORAC units--a
249-fold difference. The supplements tested included bilberry, cranberry,
chokeberry and elderberry extracts. Six other antioxidant products having grape
seed or pine bark extracts or pycnogenol ranged from 16 to 8392 ORAC units--a
525-fold difference. The results remind consumers that there are no industry
standards for the antioxidant capacity of natural product supplements and thus
little assurance of a high quality product, the researchers reported in the
Journal of the American Nutraceutical Association, 1999 (vol. 2, no. 2,
pp. 46-56). An abstract of the article is on the Web at:
http://www.americanutra.com/jana-abstracts.html.
A single serving of fresh or freshly cooked
fruits or vegetables supplies an average of 300 to 400 ORAC units. Many fruits
and vegetables--such as berries, plums, oranges, leafy greens and
beets--provide much higher antioxidant levels. By contrast, 28 of the 40 berry
extracts tested and one of the six other products wouldn't provide 300 ORAC
units in a day's suggested intake.
For more information, contact
Ronald L. Prior, (617) 556-3311, or
Guohua Cao, (617) 556-3141,
Jean Mayer USDA Human Nutrition Research
Center on Aging at Tufts University, Boston, MA
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While searching for natural compounds to
control fungi in plants, ARS scientists may have stumbled onto new antibiotics
against Streptococcus and Staphylococcus bacteria. They
discovered a new family of antibiotic compounds--not related to
penicillin--with potent antimicrobial activity. Although these compounds have
not been tested against human pathogens, some of them may prove as good as or
better than commercial antibiotics and should interest the pharmaceutical
industry. The majority of Staphylococcus and Streptococcus
species are resistant to penicillin and other antibiotics.
Six of the compounds isolated exhibit some
degree of antibiotic activity against a broad spectrum of gram-negative and/or
gram-positive genera of concern to both agriculture and medicine. The chemical
makeup of the cell wall determines whether bacteria are classified as
gram-positive or gram-negative. Agrobacterium, Erwinia and
Pseudomonas are gram-negative genera, while Bacillus,
Micrococcus, Staphylococcus and Streptococcus are
gram-positive.
Three of the compounds strongly suppressed
Staphylococcus and Streptococcus species. One of the six
compounds was very effective against all seven bacterial species tested. Just
10 micrograms per milliliter totally suppressed growth of or killed species of
gram-positive bacteria in the Micrococcus, Streptococcus,
Staphylococcus and Bacillus genera.
For more information, contact
Benny Bruton, (580) 889-7395,
South Central Agricultural
Research Laboratory, Lane, OK
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Modifying a gene that causes plants to store
excess calcium might one day make fruits, vegetables and grains a better source
of this important nutrient. A researcher found that "turning on" a
gene that controls the production of a protein called Calcium Exchanger 1
(CAX1) can increase the calcium content of plant cells. Maximizing the
production of CAX1 increased the calcium content of root cells by more than 100
percent and that of leaf cells by nearly 30 percent, the researcher reported in
Plant Cell, 1999 (vol.11, pp. 2113-2122).
He believes that CAX1 gene acts as a calcium
regulator. When the calcium content of the cellular fluid gets too high, the
gene is turned on. This triggers production of the CAX1 protein, which moves
calcium out of the cellular fluid into a storage compartment. Once the calcium
level returns to normal, the gene is turned off. By keeping the CAX1 gene
turned on, the researcher created a condition where the calcium level of the
cellular fluid was constantly depleted. While the mechanism is yet unknown, the
end result was an increase in the cell's overall calcium content.
But the experiment had its downside. The CAX1
plants did not grow well in cold temperatures or in high levels of common soil
minerals like magnesium and potassium. The next step is to limit CAX1
expression to the edible portions of plants. If successful, this might increase
the calcium content of foods and enable the plant to maintain its ability to
adapt to environmental stresses.
For more information, contact
Kendal D. Hirschi, 713-798-7012,
Children's Nutrition Research Center at
Baylor College of Medicine, Houston, TX
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If you're between the ages of 18 and 44,
chances are you didn't get enough vitamin K today . . . or any other day,
according to a recent survey. Researchers with ARS and Proctor & Gamble
Company estimated vitamin K intake from a nationwide sample of 4,742 men, women
and children.
Their findings, reported in the Journal of
the American Dietetic Association, 1999 (vol. 99, pp.1072-1076): People
over age 65 consumed more phylloquinone--the most common form of vitamin
K--than 20- to 40-year olds. Only half the females age 13 and older--and less
than half the males--got the Recommended Dietary Allowance, based on food
intake diaries the survey volunteers kept for 14 days. The RDA is 65 micrograms
per day for adult females and 80 mcg/day for adult males.
Long known for its role in blood clotting,
vitamin K is gaining recognition for its importance to the integrity of bones.
It activates at least three proteins involved in bone health. Phylloquinone is
found in some oils, especially soybean oil, and in dark-green vegetables such
as spinach and broccoli. One serving of spinach or two servings of broccoli
provide four to five times the RDA.
In a study with Yale University School of
Medicine, the researchers found that people absorb vitamin K just as well from
broccoli as they do from oil. That's contrary to the notion that this
fat-soluble vitamin is better absorbed from oil or oil-based supplements than
from vegetables with their high water content. The study, reported in the
American Journal of Clinical Nutrition, 1999 (vol. 70, pp. 368-377),
also showed that 60- to 80-year-olds can increase their blood vitamin K levels
just as readily as 20- to 40-year-olds by increasing their vitamin K intake.
For more information, contact
Sarah L. Booth, (617) 556-3231,
Jean Mayer USDA Human Nutrition Research
Center on Aging at Tufts University, Boston, MA
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A person's nutritional status can affect
behavior and learning. But only a handful of psychologists are involved in
nutrition studies. So an ARS psychologist found a way to clone himself via the
Internet. He computerized a battery of tasks for testing the cognitive and
motor functions of study volunteers. He sends the tests to study leaders,
receives the raw data, scores and analyzes the data in his lab, and returns the
results--all electronically. So far, he has collaborated on nutrition studies
in China, Guatemala, New Zealand, San Francisco, and Brownsville, Texas.
In the China study, he and researchers at the
University of Texas Medical Branch in Galveston tested 1,400 school children
via computers. It was the first long-distance study of its kind. And it was
highly standardized, since the computer doesn't vary how it administers the
tasks. Results showed that poor, urban Chinese children improved in perception,
memory and reasoning skills after getting extra zinc or zinc plus other
essential vitamins and minerals.
Unlike the limited scope of most computerized
tests, the ARS battery can assess the gamut of psychological functions. An
overview of the battery appears in the American Journal of Clinical
Nutrition, 1998 (vol. 68S, pp. 470S-475S). The battery can be tailored to
fit any age, ethnic group or study protocol. Soon there will be a Windows
version, capable of incorporating video, sound and external devices such as an
electroencephalogram (EEG) for measuring volunteers' electrophysiological
responses.
For more information, contact
James Penland, 701-795-8471,
Grand Forks Human Nutrition Research
Center, Grand Forks, ND
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Tomatoes with much higher levels of lycopene
may be available in the future if ARS research pans out. Lycopene, which gives
tomatoes their bright red color, may help reduce the risk of some cancers,
according to epidemiological research at the Harvard Medical School and Harvard
School of Public Health.
While working with tomato tissue cultures, an
ARS biologist got more than she expected. Not only did the culture develop into
a tomato fruit, the fruit's green outer leaves, known as the calyx, also
ripened into fruitlike tissue. In this particular tomato variety, called VFNT
Cherry, low growing temperatures triggered ripening in nonfruit tissue. But the
process doesn't work outside tissue culture. Something else in the plant
prevents this transformation under normal growing conditions.
The fruit itself was very dark red with a
lycopene content 10 times the amount in most commercial tomatoes, the
researchers reported in the Journal of Agricultural and Food Chemistry,
1998, (vol 46, pp. 4577-4582). Now they are looking for the genes that are
activated to increase lycopene production so they can learn how to activate the
genes in commercial varieties.
For more information, contact
Betty Ishida, (510) 559-5726,
Western Regional Research Center, Albany,
CA
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Some green beans outdo others as
a source of bone-building calcium. The difference, according to researchers,
can depend on how much water flows through the plants. The scientists compared
calcium content in six bean varieties. The top performer, Hystyle, was also the
stingiest water user. Hystyle green beans have about double the calcium content
of a variety called Labrador. That's because Hystyle is better at conserving
water.
Water dilutes calcium moving
through a bean plant, reducing the amount reaching the pods. Tiny pores called
stomates open and close to control the speed at which water enters and leaves a
plant. This transpiration, as it is called, is genetically and environmentally
controlled. Overall transpiration in Hystyle was about half that of Labrador.
The lower transpiration meant higher calcium concentrations in Hystyle's xylem
stream. The xylem transports liquid and mineral nutrients from roots to shoots
somewhat as a person's arteries carry oxygen-rich blood.
While dairy products are
excellent calcium sources, beans and other veggies can also provide a
substantial portion of the recommended intake. And these foods could play a
bigger role for people who can't tolerate milk sugar.
For more information, contact
Michael A. Grusak, (713) 798-7044,
Children's Nutrition Research Center at
Baylor College of Medicine, Houston, TX
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First introduced in the United States four
years ago as a result of ARS patents, nontoxic biological coatings are
replacing synthetic chemicals for controlling rot-causing fungi on apples,
pears and citrus after harvest. ARS recently signed an agreement with Micro-Flo
Company of Memphis, Tennessee, to finish developing the next generation of
biofungicides for fruit packinghouses. Micro-Flo expects to have a product on
the market within two years.
Researchers combined two bioactive substances
with the yeast Candida saitoana. Innocuous to people, the yeast is a formidable
competitor against fungi that attack fresh fruits. The bioactive substances are
chitosan--a naturally occurring fiber found in some weight-loss products--and a
synthetic sugar used as a glucose substitute. Chitosan acts as a natural
fungicide and turns on defensive enzymes in the fruit itself. It also forms a
film on the fruit that holds in carbon dioxide, thus increasing shelf life. The
synthetic sugar, on the other hand, tricks the fungi into perceiving it as
food, but they can't use it.
Unlike the earlier biofungicides, the new
coating controls fungi that already had a toehold on the fruit. In several
years of tests in commercial packinghouses in California and Florida, the new
biofungicide proved as effective against rot-causing fungi as the two leading
synthetic fungicides. Under the new agreement, Micro-Flo and ARS scientists
will optimize its formulation and fine-tune its application.
For more information, contact
Charles L. Wilson, (304)
725-3451, ext. 330, Appalachian Fruit
Research Station, Kearneysville, WV
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A USDA water quality program is changing the
landscape of American agriculture. The program began in 1990 to reduce the
amount of pesticides reaching groundwater. It was expanded three years ago to
address broader environmental concerns, including harmful algal blooms. These
blooms have created a widening "dead zone" in the Gulf of Mexico,
where lack of oxygen kills shellfish. Pfiesteria and Red Tide algal blooms also
have been implicated in fish-kills along the East Coast.
Reducing nitrogen loadings into the
Mississippi River by 20 to 30 percent could increase oxygen levels in the Gulf
by 15 to 50 percent, according to a recent National Science and Technology
Council report. The USDA water quality program continues to show farmers how to
reduce nitrogen loadings from commercial fertilizer and animal manure.
The program originally involved large
Midwestern sites called Management Systems Evaluation Areas (MSEA). The 1996
merger with USDA's Agricultural Systems for Environmental Quality brought in
concerns about phosphorus, air quality, soil management and off-site impacts.
The merger also brought in Ohio's Lake Erie Basin, the Mississippi Delta
region, and the eastern coastal plain.
For more information, contact
Dale A. Bucks, (301) 504-7034,
ARS National Program
Leader for Water Quality and Management, Beltsville, MD
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