Older people who want to lift their spirits and get more quality sleep
might consider joining the local gym. Regular resistance training significantly
reduced depression and improved sleep in mildly to moderately depressed people
in their 60's, 70's and 80's.
Half of the 32 volunteers exercised leg, hip and upper torso muscles on
pneumatic resistance equipment for 45 minutes three times each week. The other
16--the control group--attended a group health education meeting. Resistance on
the exercise equipment was set at 80 percent of the maximum load each volunteer
could complete in a single repetition on that day.
At the end the 10-week study, 14 of the 16 exercisers no longer met
criteria for depression. Their depression scores improved two to three times
above the control group, the researchers reported in the Journal of
Gerontology (vol. 52A (1): M27-35). Quality of sleep improved in more than
one-third of the exercisers compared to none of the control group, they
reported in Sleep (vol. 20 (2): 051-055).
Elders are at high risk for depression. Researchers with ARS and Harvard
Medical School wanted an alternative or an adjunct to anti-depressants because
they can cause side effects, interact adversely with other medications and
increase the risk for falls or delirium. Moreover, they don't counteract
frailty or improve mobility and function.
Progressive resistance training, on the other hand, improved the
volunteers' strength, vitality, morale and ability to maintain social
activities compared to the control group. It also reduced physical pain and
emotional stress that would otherwise interfere with normal activities. This is
the first controlled study to show that exercise is an effective antidote for
depression and poor sleep in older men and women. And it's the first study to
show that resistance training can improve sleep in any age group.
For more information, contact
Maria A. Fiatarone, (617)
556-3075, Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts,
Boston, MA
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Cutting calories may inadvertently slow dieters' reaction times. And
that effect may continue for weeks after the diet ends, ARS researchers and
their British colleagues found. Reaction time lengthened by 11 percent in a
group of 14 women volunteers who went on a strict reducing diet. It continued
to slow for 3 weeks after the diet ended. The scientists measured reaction
times during the 21-week study by determining how long it took the women to hit
the space bar on a computer keyboard after a white star appeared on the screen.
Now, the scientists want to find out whether the slowdown lowers dieters'
alertness--and thus increases their risk of accidents--or whether the even
longer term diets might increase such risks. The overweight but otherwise
healthy volunteers, age 25 to 42, ate only half of the number of calories
needed to maintain their beginning weight during 15 weeks of the study. They
lost an average of 27 pounds. Their increase in reaction time confirms an
earlier finding by the British investigators, who are with the British
Biotechnology Sciences Research Council.
Further study could lead to new understanding of how the body uses calories
and nutrients for thought and action. Such information could be used by
healthcare professionals to improve diet and exercise regimens for overweight
Americans.
For more information, contact Mary J. Kretsch, (415) 556-6225,
Western Human Nutrition Research Center, San Francisco, CA
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People with high blood pressure would benefit from redesigning their
diet in addition to avoiding salt. That's the message from the multi-center
DASH study recently reported in the New England Journal of Medicine
(vol. 336 (16): 1117-1124). Adding several servings of fruits and vegetables
and a few low-fat dairy foods to a reduced-fat diet significantly lowered blood
pressure in African-American and Caucasian men and women.
ARS dieticians helped design the menus used to feed nearly 460 volunteers
at four centers around the country. They also prepared all meals for The Johns
Hopkins University in Baltimore. One third of the volunteers got a
"typical" U.S. diet--low in fruits, vegetables and dairy products,
with 37 percent of calories from fat. This group served as controls. Another
third ate the same amount of fat but with eight to 10 servings of fruits and
vegetables daily. The third group got a low-fat diet with the extra fruits and
vegetables plus three servings of dairy products. This combination diet had 27
percent of calories as fat with only 6 percent saturated fat.
After eight weeks on this combination diet, systolic pressure dropped an
average 11.4 points and diastolic pressure was down 5.5 points in the
volunteers with high blood pressure. That's about what can be achieved with a
single medication. The average drop for all participants, including those with
normal blood pressure, was also significant--5.5 and 3 points, respectively.
The combination menu was designed to increase intakes of fiber and three
minerals important for blood pressure regulation--potassium, magnesium and
calcium. Bananas, dried fruits and melon pieces, for instance, supplied extra
potassium, which totaled 4,700 milligrams daily. Spinach, dried fruits,
broccoli and scallions helped raise the magnesium intake to 500 mg. daily. And
low-fat dairy products brought calcium intake up to 1,200 mg. Fiber intake was
30 grams daily. Salt was held at 3,000 mg. for all diets. Menus for all three
diets are posted on the Web at http://dash.bwh.harvard.edu.
For more information, contact Priscilla D. Steele, (210) 402-0030,
retired from the Beltsville Human Nutrition Research Center, Beltsville, MD; or
Lawrence J. Appel, Johns Hopkins
University School of Medicine, Baltimore, MD
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Diets high in antioxidant foods appear to protect the brain against
oxidative damage, if rat studies by ARS and University of Denver scientists are
any indication. Oxidative damage is thought to lead to age-related disfunctions
such as loss of memory or motor coordin ation. But rats that ate extracts of
strawberries, blueberries or spinach as part of their daily diet fared far
better on brain cell function tests than the animals getting chow alone. The
fruit and vegetable extracts offered at least as much protection as vitamin E
against oxidative damage induced by exposure to a high-oxygen atmosphere.
Earlier, these foods scored highest among commonly eaten fruits and
vegetables in a test-tube-type assay of total antioxidant capacity. The next
step was to assess their protective power in animals. So the scientists added
either strawberry extract, vitamin E or nothing to the rats' normal diet for
eight weeks. Then they put the animals in chambers under 100 percent oxygen for
two days. They later repeated the study using blueberry and spinach extracts.
High oxygen exposure alters brain function in young rats in a manner
similar to the aging process. In both cases, brain cells are less sensitive to
neurotransmitters, such as dopamine or norepinephrine, that prompt them to send
or stop sending information.
The scientists measured the rats' response to three different types of
brain function controlling memory, movement and growth of nerve cells. In all
three cases, decline in these functions due to oxygen exposure was
significantly--often dramatically--reduced by strawberry extract as well as by
vitamin E. Preliminary data indicate that blueberry extract provides even more
protection to rats' brains. If this finding holds up, it supports the
usefulness of the chemical assay--known as ORAC--for identifying
health-promoting foods because blueberries had the highest antioxidant capacity
of the fruits and vegetables tested.
For more information, contact James A. Joseph, (617) 556-3178,
Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts, Boston,
MA
Back to Contents
Older people whose heart rate soars and energy dives during aerobic
exercise may want to take a closer look at their magnesium intake. That's the
message from the first study to look at the effect of low magnesium intakes on
the physiological function of people over age 55. A group of post-menopausal
women experienced a significant drop in their work efficiency when their
magnesium intake was reduced to a little more than half of the Recommended
Dietary Allowance for three months. That occurred even though blood magnesium
levels showed no sign of deficiency.
During the study, the low-magnesium diet affected the women's physiological
function in three ways as they cycled on an ergometer. First, they spent 10 to
15 percent more energy, as indicated by a rise in oxygen consumption, compared
to when they were getting ample magnesium. Second, their heart rate increased
about 10 beats a minute. And third, the amount of magnesium stored in their
muscle tissue dropped measurably.
According to the latest USDA nationwide food consumption survey, fewer than
one-third of people over age 50 consume the recommended amount of magnesium
through their diet. But it's easy to get enough magnesium to prevent these
symptoms in a low-fat diet. Eat more vegetables, especially dark leafy greens,
more whole wheat and other whole grain breads, cereals and pastas and more
dried beans.
For more information, contact
Henry C. Lukaski, (701)
795-8353, Grand Forks Human Nutrition Research Center, Grand Forks, ND
Back to Contents
The equations used to estimate the number of calories adolescent females
burn while resting are inaccurate for African Americans. That's what
researchers found when they carefully measured the basal metabolic rate (BMR)
of 76 white females and 42 black females between 8 and 17 years old. The
finding is important because BMR accounts for between 50 and 70 percent of the
calories we burn daily. Clinicians routinely use BMR to estimate the energy
needs of patients. Government agencies use it to recommend calorie intakes.
The researchers had suspected that the current equations do not reflect the
energy needs of children and adolescents, particularly non-white youths,
because they were derived from measurements done mostly on white adults. What's
more, most of the measurements were done during the first half of the century
when equipment and methods were less sophisticated.
Based on the new measurments, nine of the 10 equations they evaluated
significantly overestimated BMR in the black girls, and half overestimated BMR
in the white girls. The ethnic differences became obvious when the two groups
were matched for age, weight and sexual maturity. In six of the 10 equations,
the overestimation was significantly greater for the black girls--averaging 77
calories daily--than for the white girls--averaging 25 calories daily.
The black girls were heavier, had a higher body mass index than the white
girls of the same age and were more sexually mature--a factor that increases
overestimation, the scientists found. They reported their findings in the
Journal of Applied Physiology (vol. 81(6): 2407-2414). Their conclusion:
Ethnicity should be included in future measurements of basal metabolic rate and
in refining equations used to estimate it.
For more information, contact William
W. Wong, (713) 798-7168, Children's Nutrition Research Center, Houston,
TX
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Girls and boys absorb two important bone-building minerals--calcium
and magnesium--from snap beans as easily as they absorb them from milk. What's
more, there's good potential for increasing the calcium in snap beans through
breeding. That's good news to ARS-funded researchers looking for good sources
of calcium to replace the 24-35 percent drop in milk consumption among children
and teenagers since the late 1970's. Snap beans are a popular vegetable among
this age group.
The researchers measured the rate of calcium absorption from milk and
compared it with snap beans, broccoli and spinach in 12 girls and boys ages 9
to 14. Although it takes about five cups of cooked snap beans to equal the
calcium in one cup of milk, the rate of absorption was the same from both
sources. The absorption rate was about 5 percent higher from broccoli, which
provides about one quarter as much calcium as an equal amount of milk. But the
calcium in spinach was poorly absorbed because of a high content of
absorption-blocking compounds known as oxylates.
In tests of magnesium absorption from snap beans and spinach, the youths
absorbed the mineral from these two vegetables and milk at about the same rate.
Snap beans provide nearly as much magnesium as milk, but spinach provides
nearly five times more.
The researchers also collaborated with University of Wisconsin plant
breeders to assess 64 unique types of snap beans, looking for differences in
calcium content. They found wide differences, indicating that calcium content
has a strong genetic basis. This means breeders can develop snap bean varieties
with extra calcium. One commercial variety--'Hystyle'--was among those with the
highest calcium levels. The researchers also found that younger, skinnier snap
beans of any variety had significantly more calcium than older, fatter pods. So
look for the "string bean."
For more information, contact Steven Abrams (absorption) or
Michael Grusak (breeding), (713)
798-7000, Children's Nutrition Research Center, Houston, TX
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A couple drops of blood are all that's needed to accurately assess a
person's natural ability to fight off infections or supress cancer, thanks to a
new technique developed by an ARS immunologist. It could lead to routine
screening of infants and children, the elderly and others whose immune
competence may be suspect.
The technique more closely mimics what happens inside the body because it
tests the ability of a chemical stimulant or antigen to prompt T cells to
multiply in whole blood--a familiar milieu--rather than among foreign proteins
now used to culture these lymphocytes. It requires only 0.4 milliliters or less
of blood. That's one twenty-fifth of the amount now drawn, making the technique
ideal for infants and small children and for people from cultures opposed to
giving blood.
Another plus: It's estimated to cost 35 to 40 percent less in equipment and
supplies than the current technique. At the same time, it more than triples the
number of samples that technicians can handle in one day. And the technicians
need far less training to produce accurate readings because there's no need to
separate cells from blood plasma or count them under a microscope.
Since 1991, the technique's accuracy has been validated in studies of
Chinese populations, screenings of Ranger trainees for the U.S. Army, nutrition
studies at ARS centers and in a recent study of normal and HIV-infected
infants.
For more information, contact Tim
R. Kramer, (301) 504-8396, Beltsville Human Nutrition Research Center,
Beltsville, MD
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A new gooseberry variety named Jahn's Prairie could give most of today's
Americans a chance to enjoy this plump, tart, native fruit. Gooseberries are
high in vitamin C and are popular in pies and preserves in England. But many
wild gooseberry plants in the United States were destroyed decades ago because
they can harbor a disease that threatened the pine industry. Jahn's Prairie,
which resists the white pine blister rust, was selected from the wild in
Alberta, Canada, by ARS researchers. Last year, ARS jointly released the
variety with Agriculture and Agri-Food Canada.
The variety could spark new life into a developing commercial gooseberry
industry in the United States. The industry was largely abandoned here in the
1940's when a federal law called for eliminating gooseberries and their
cousins, currants, because of the rust. The law was repealed in 1966 but some
states still prohibit growing the fruits. Gooseberries grow well in the Pacific
Northwest, the Midwest, the East and in Canada. The new variety also resists
powdery mildew, a fungal disease of the leaves, stems and berries.
For more information, contact Kim
E. Hummer, (541) 750-8712, National Clonal Germplasm Repository, Corvallis,
OR
Back to Contents
A faster, more accurate test to detect Brucella melitensis bacterium
in unpasteurized goat's milk and cheese can help prevent undulant fever in
humans. Most foodborne cases of undulant fever come from unpasteurized goat's
milk and cheese from Mexico. The disease can cause chills, fever, fatigue and
an aching similar to arthritis. A biotechnology technique called polymerase
chain reaction (PCR) cuts the test's identification time in food samples from
weeks to a single day. Quick identification is critical so contaminated foods
can be removed from grocery stores. About two-thirds of all U.S. cases of
undulant fever are attributed to infection with B. melitensis.
For more information, contact Betsy
J. Bricker, (515) 239-8310, National Animal Disease Center, Ames, IA
Back to Contents
Pea fiber has solved the problem of producing a high-energy beef snack to
sustain military troops during times of great physical stress, such as combat
or field maneuvers. While a low-fat diet is normally recommended, the ideal
snack for high-demand physical activity would contain 40 percent fat for plenty
of energy, plus 30 percent carbohydrates, 25 percent protein and 5 percent
moisture. However, the high temperatures needed to make this product also melt
away the fat.
ARS scientists found that by adding pea fiber--the stuff that gives pea
soup its body--meat retains almost all of the fat during heating without
affecting flavor.
This fat-holding capability of pea fiber could prove useful in low-fat
foods. That's because fat degrades over time, and any loss of fat in low-fat
foods could mean loss of flavor.
For more information, contact Brad Berry, (301) 504-8994, Meat
Science Research Laboratory, Beltsville, MD
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Irradiation could become more practical as a quarantine treatment to
prevent fruit flies from spreading via shipments of grapefruit and other
produce. Studies suggest that it may be possible to reduce by half or more the
very low levels of gamma ray energy now used to interrupt insects' development.
If confirmed by further research, irradiation could be done more quickly and on
fruits that can be damaged by the gamma ray doses now used. Lowering the dose
would make irradiation more feasible as an alternative to fumigation by methyl
bromide, scheduled to be phased out by 2001.
For two years, Hawaiian papayas and other tropical fruits have been
approved for shipping to the Chicago area. Exposure to 250 Grays (Gy) of gamma
rays ensures that no oriental or Mediterranean fruit flies hidden inside the
fruit will survive to adulthood. But the irradiation amount needed to obtain
this exposure level could damage orange, mango, grape, avocado and other fruits
in a commercial shipment. ARS tests with a few thousand grapefruit indicate 50
Gy may be adequate to halt Mexican fruit flies hiding inside the fruit.
For more information, contact Guy
J. Hallman or Donald B. Thomas,
(210) 565-2647, Subtropical Agricultural Research Laboratory, Weslaco, TX
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