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A new Center for Nutrition Policy and Promotion has been established under
Ellen Haas, USDA Under Secretary for Food, Nutrition and Consumer Service
(FNCS) with Dr. Eileen Kennedy serving as executive director.
To help staff this center, the Agricultural Research Service has transferred
to FNCS its family economics and nutrition education research groups. The
center will serve as the focal point in USDA for coordinating nutrition policy
issues, including publication of the Dietary Guidelines for Americans and the
Food Guide Pyramid, as well as nutrition promotion activities.
ARS retains the programs responsible for compiling the nutrient databases of
foods and for conducting nationwide food consumption suveys. These two units
have been incorporated into ARS' Beltsville Human Nutrition Research Center.
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Grandmother-age women may soon be flocking to the gym to strengthen thigh
and torso muscles and thus prevent osteoporosis and related fractures. A
year-long study of women aged 50 to 70 shows that strength training can
preserve bone density and prevent losses in muscle strength, balance and
physical activity. Such losses lead to falls--the greatest risk factor for
fractures in the elderly.
Twenty of the 39 volunteers strengthened muscles in the abdomen, the upper
and lower back, the front and back of thighs and the buttocks on pneumatic
equipment for just 40 minutes twice a week. The resistance was set at 80
percent of the maximum load each could handle at a given session. Meanwhile, a
control group of 19 women continued their normal lifestyle.
At the end of the year, the trained group had gained 1 percent more bone
density at the hip and spine compared to a 2.5 percent loss in the control
group. They also increased strength in the trained muscles ranging from about
35 to 76 percent above the control group. Their balance improved 14 percent.
And their spontaneous physical activity--excluding the training
sessions--increased by an average 27 percent calories, whereas it decreased in
the control group by nearly as much. The researchers are now testing the
effectiveness of comparable exercises they developed that can be done at home
with simple, low-cost leg weights and dumbbells.
For more information, contact Miriam E. Nelson, (617) 556-3094, Jean
Mayer USDA Human Nutrition Research Center on Aging at Tufts, Boston, MA.
Contrary to common belief, a high-intensity strength training program can be
an effective way for older people to maintain their weight while eating more.
And it can reduce body fat, according to a study of 12 men and women in their
late fifties, sixties and seventies. The volunteers lived at the USDA center
during the 3-month study so researchers could account for all of the calories
they consumed as well as measure how many calories they burned. Three times a
week, the volunteers exercised muscles in the upper leg, upper torso and arms
at 80 percent of the maximum weight each could lift at a given session.
After 12 weeks, they were eating an average 15 percent more calories just to
maintain their starting weight, while losing an average 4 pounds of body fat.
One-third of those extra calories were burned during the resistance exercises
themselves. Another one-third were needed to fuel an increase in the people's
resting metabolic rate--the energy needed to keep the leaner body functioning
while at rest. The research demonstrates the benefits of resistance training in
helping older people balance calories burned with calories consumed while
losing body fat and maintaining strength for daily activities.
For more information, contact Wayne W. Campbell, (814) 865-3453, now at
the Noll Physiological Research Center, Pennsylvania State University,
University Park, PA.
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Slashing the number of calories rats consume throughout life is proving to
avert age-related loss of brain function. It's well known that life-long
calorie restriction--the laboratory equivalent of the ancient practice of
fasting--dramatically prolongs life in laboratory animals. In this study, the
brain cells of inactive old rats responded to specific chemical signals like
those of young rats when they were served only 63 percent of the calories they
would normally have eaten.
The receptors for these chemicals, called muscarinic receptors, generally
decline in mid-life. This leads to a loss of memory and some motor functions
dependent on these receptors. But in the calorie-restricted rats, these
receptors functioned 25 percent better than in a control group that got all the
food they wanted. The finding is in line with studies by others showing that
calorie restriction throughout life spares dopamine receptors, which control
movement and decline dramatically with aging.
For more information, contact James A. Joseph, (617) 556-3178, Jean Mayer
USDA Human Nutrition Research Center on Aging at Tufts, Boston, MA.
On the other hand, slashing the calorie intake of middle-aged rats, did not
prolong life, dampening the hope that people might develop fewer cancers and
other diseases of aging by limiting calorie intake after age 50. That finding
is in sharp contrast to hundreds of studies done over several decades that
restricted animals' calorie intake from youth. Rats lived 30 to 40 percent
longer when their calorie intake was two-thirds or less of what they would
normally eat. Nutrition researchers theorize that lifelong calorie restriction
cuts the number of tumors--the primary cause of death in test rats--by lowering
the rate of cell growth. Also, fewer calories may reduce kidney disease.
In the new study, however, male rats ate as much as they wanted for their
first 18 months-- equivalent to the first 50 years for a man. Then they got 33
percent less food for the rest of their lives, with little or no effect on life
span. Apparently certain disease processes have already begun by this age, too
late to be helped by calorie cutting.
For more information, contact Ruth D. Lipman, (617) 556-3204, Jean Mayer
USDA Human Nutrition Research Center on Aging at Tufts, Boston, MA.
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As people age, they lose the automatic ability to regulate appetite and so
maintain a constant weight, according to a study of both young and older men.
The findings help to explain why people tend to gain weight and double body fat
during middle age--which is a major national health problem--then progressively
lose weight and lean body mass after age 65. This contributes to malnutrition
so common in the oldest.
In the study, 9 older men kept on the extra pounds gained during 3 weeks of
eating about 1,000 calories more than their normal intake each day. Ten young
men, however, automatically ate less and dropped back to their normal weight
over the following 6 weeks. In fact, much of the weight loss occurred during
the first 10 days after overeating, even though all volunteers were instructed
to eat normally and not try to lose weight.
Older men don't bounce back from undereating, either. After 3 weeks of
eating about 800 calories less than usual, they didn't automatically increase
their intake. But the young men gained back more than they lost in the 6-week
follow-up despite the request to eat normally. The findings are the first
direct evidence of an age-related loss of appetite control.
For more information, contact Susan Roberts, (617) 556-3237, Jean Mayer
USDA Human Nutrition Research Center on Aging at Tufts, Boston, MA.
Slim and trim adult rats that were put on a yo-yo diet had 3 to 4 percent
more body fat than control animals kept on a steady calorie intake. These
findings suggest that weight cycling-- gaining, losing, and regaining--could
tip the scale in favor of fat accumulation in the body, at least for a while.
Animals and people appear to adapt to a reduction in calories by storing more
fat in times of plenty to prepare for the next deficit. A 3- to 4-percent
increase in fat is not much for people of normal weight. But, it can be quite
significant for obese people who often have much larger weight swings than the
study rats.
Because rats normally keep growing throughout life if allowed to eat all
they want, the researchers limited growth of the test animals prior to the
study so it would more nearly approximate that of adult humans. Then they put
one group of rats through three weight cycles in which they gained 10 percent
above starting weight, lost 10 percent below, then returned to starting weight.
The other group remained on the growth restricting diet. Both groups had the
same energy intake and expenditure at the end of each cycle.
For more information, contact Paul W. Moe, (301) 504-8988 Beltsville
Human Nutrition Research Center, Beltsville, MD.
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Copper deficiency in test animals causes symptoms that resemble those of
human diabetes and aging, and new findings shed light on why. They support the
hypothesis that copper deficiency increases the spontaneous attachment of
glucose molecules to proteins, known as protein glycation. Left unchecked, the
dangling glucose molecules attach to a second site on the protein, producing
"cross links". This prevents proteins from functioning because they
can't change shape to fit into specific receptor sites like puzzle pieces fit
into in only one spot. Protein glycation is known to increase in all people as
they age and to cause tissue damage in diabetics.
To test the hypothesis that copper deficiency promotes the process, an ARS
researcher administered daily doses of the drug aminoguanidine to half of a
group of copper-deficient rats. The drug does not block the initial attachment
of glucose but prevents the formation of cross links. At the end of the study,
treated rats had less of the anemia and heart damage characteristic of copper
deficiency, whereas untreated rats died prematurely from these conditions.
For more information, contact Jack T. Saari, (701) 795-8499, Grand Forks
Human Nutrition Research Center, Grand Forks, ND.
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Very low-birth-weight infants taking mother's milk through a tube in their
stomachs gain weight faster when given only the portion of the milk produced 2
to 3 minutes after the flow begins. That's according to a study of 15 preemies
ranging from a little more than 1 pound to nearly 5 pounds at birth.
This hindmilk, as it is called, is richer in fat than the initial flow and
offers a concentrated source of calories. As a result, the preemies gained an
average 1/4 ounce more each day than when fed regular breastmilk. That weight
is closer to what they would have gained had they still been in the uterus.
Very low-birth-weight infants often have difficulty gaining weight on
breastmilk and are switched to formula. But they lose the substances in
breastmilk that appear to protect them against potentially life-threatening
infections. So researchers are looking for ways to approximate fetal
development with mother's milk.
For more information, contact Richard J. Schanler, (713) 798- 7000,
Childrens Nutrition Research Center, Houston, TX, or Christina J. Valentine,
(713) 770- 1380, Baylor College of Medicine, Houston, TX.
Several large feedings rather than a continuous feeding may promote more
natural maturation of the intestinal tracts of very premature infants and
full-term babies who need to be fed through a tube for extended periods. A
preliminary study of piglets found that the group that got four "milk
meals" through a tube into the stomach had significantly more intestinal
growth and greater amounts of some digestive enzymes than those fed
continuously.
Piglets were tested because their digestive system closely resembles that of
humans. Researchers were looking for ways to encourage the intestinal tract to
develop as naturally as possible in situations like tube feeding. Normally, the
small intestine undergoes dramatic growth and development of its digestive
capability after birth, particularly in preterm infants. And the enzyme that
digests the primary milk sugar, lactose, increases the most during the last
trimester of pregnancy.
Researchers are now testing these 2 feeding regimens in 80 low-birth-weight
infants and, at the same time, determining the optimal time to begin feeding--3
to 4 days after birth versus 7 to 10 days.
For more information, contact Robert Shulman, (713) 798-7145, Children's
Nutrition Research Center, Houston, TX.
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Do supplements of fat-soluble vitamins compete with one another in the
intestinal tract for absorption, as some reports suggest? No, according to
studies using ferrets as a model. In fact, reasearchers found that a dose of
vitamin E equivalent to the Recommended Dietary Allowance (RDA) for humans
actually enhanced beta carotene uptake fourfold. Raising the vitamin E dose to
20 times the RDA increased beta carotene uptake fourteenfold to nineteenfold.
Vitamin E also increased the conversion of beta carotene into vitamin A in line
with the amount of vitamin E taken.
A dose of beta carotene, on the other hand, didn't enchance vitamin E
uptake. But it didn't block it either. If people respond as the ferrets did,
vitamin E supplements may be used to improve beta carotene and vitamin A status
when ingested together. Both nutrients are important antioxidants. Vitamin E
supplements have been associated with a lower rate of heart disease. And a high
beta carotene intake has been linked to reduced risk of several cancers.
For more information, contact Xiang-Dong Wang, (617) 556-3130, Jean Mayer
USDA Human Nutrition Research Center on Aging at Tufts, Boston, MA.
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A microscopic organism that attacks disease-carrying mosquitoes is being
tested in Florida field studies. They’re the first outdoor tests in the
United States of a foreign microorganism to control Aedes aegypti
mosquitos, which spread yellow fever and dengue. These viral diseases are not
currently found in the United States but have the potential to spread here from
other parts of the world. A microsporidium, Edhazardia aedis, infects the
mosquitoes with tiny spores that eventually weaken or kill the insect. Female
mosquitoes that survive spread the microsporidium to the next generation
through their eggs.
In lab tests, E. aedis has had no long-term, adverse effects on
animals or beneficial insects such as honey bees. The mosquito has developed
resistance to insecticides. And the current control method of removing standing
water in which the pest breeds often isn’t practical. If the biocontrol
field tests are successful over the next few years, the microsporidium could be
developed commercially as a natural way to control A. aegypti
mosquitoes.
For more information, contact James J. Becnel, (904) 374-5961, Medical
and Veterinary Emtomology Research Lab, Gainesville, FL.
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ARS has enlisted Monarch Foundation for Medical Research in Cincinnati to
further simplify a computerized system for monitoring what people eat.
Nutritionists translate this data into nutrient intakes to determine what
nutrients need to be emphasized in educational and feeding programs. ARS
scientists developed the Nutrition Evaluation Scale System (NESSy) several
years ago. Today, volunteers in nutrition studies enter data into NESSy at home
on a notebook computer, which is linked to a food weighing scale to accurately
log the foods that are eaten.
Researchers now want to downsize NESSy to run on a smaller computer, perhaps
palm-sized, so volunteers can more conveniently take the program to work or
even to a restaurant. NESSy is cheaper, more accurate and more efficient than
the traditional approach to at-home food monitoring, in which volunteers are
supposed to keep a handwritten record or daily food diary. A simplified NESSy
eventually might be used in the national food consumption surveys.
For more information, contact, Mary J. Kretsch, (415) 556-6225, Western
Human Nutrition Research Center, San Francisco, CA.
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An ARS recipe using rice flour for making bread has been newly adapted to
home breadbaking machines. ARS scientists developed a recipe some 20 years ago
for people with celiac disease, a wheat allergy. Now the researchers have
revised the recipe to give the home baker a new choice among rice breads they
can make with the countertop appliance. The machine automatically mixes, kneads
and bakes the rice-flour dough, but must be assisted after the kneading cycle.
The recipe calls for methyl cellulose, a food processing ingredient. Methyl
cellulose traps bubbles given off by yeast, making the dough rise and giving
the bread its light texture. The recipe also requires short- or medium-grain
white or brown rice, sold at health food stores and Asian grocery markets. Home
bakers can modify the flavor by substituting honey or brown sugar for table
sugar, or by adding small amounts of spices, fruits or nuts. The recipe was
developed by Maura Bean at the ARS Western Regional Research Center in Albany,
Calif.
For copies of the recipe, write to Marcia Wood, USDA-ARS Information
Staff, 800 Buchanan Street, Room 3014, Albany, CA.
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Black Emerald, a new seedless grape, is ready to harvest in mid-May when no
other top-quality, U.S.-grown, black seedless grape is on the market. ARS
researchers made Black Emerald available to growers this spring after 7 years
of tests. In the next 3 to 5 years, growers may plant enough vines to market
the grapes nationally. Black Emerald's sweet, juicy grapes are about the size
of a dime. The flesh is translucent and firm--almost crisp. Growers funded part
of the research through the California Table Grape Commission.
For more information, contact David W. Ramming or Ronald Tarailo, (209)
453-3160, Horticultural Crops Research Laboratory, Fresno, CA.
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Insect pathogens are the latest weapons against the citrus leafminer, a new
pest eating its way through Florida's citrus groves. Leafminers, which appeared
in May 1993, have spread rapidly throughout Florida and have become a threat to
citrus groves and nurseries. Among the environmentally friendly pathogens
deployed against the leafminer: Paecilomyces fungi, Bacillus
thuringiensis bacteria, a nuclear polyhedrosis virus and Steinernema
carpocapsae nematodes. The pathogens being used won't attack any beneficial
insects and will harm only their target pest.
For more information, contact Jeffrey P. Shapiro or William J. Schroeder,
(407) 897-7300, U.S. Horticultural Research Laboratory, Orlando, FL.
A little too much of the female moth's perfume is part of a three-pronged
approach for controlling diamondback moths and other crop pests without using
chemicals. Diamondback moths are the most destructive insect pests of broccoli,
cauliflower, cabbage and other cruciferous vegetables worldwide. Normally, male
moths welcome the female's sex scent, called a pheromone. That chemical scent
helps the males find females ready to mate.
To interrupt reproduction, ARS scientists are flooding crop fields in
Florida with the synthetic female pheromone. Males become confused, unable to
pick up a female's scent. In field tests, only 36 percent of female moths had
mated in scent-laden fields, compared to 86 percent in conventional fields.
That meant pesticide sprayings were reduced from 15 to 3 on the fields where
pheromones were used. Other control tactics include parasitic wasps that attack
moth larvae, and Bt insecticide that kills surviving larvae without damaging
the beneficial wasps.
For more information, contact Everett Mitchell, (904) 374-5710, Insect
Attractants, Behavior and Basic Biology Research Lab, Gainesville, FL.
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