Older people who want to lift their spirits and get more quality sleep might consider joining the local gym. In a 10-week study, 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, while the other 16--the control group--attended a 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 of the 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. Quality of sleep improved in more than one-third of the exercisers. The control group reported no improvement. Elders are at high risk for depression because of the loss of health, function, loved ones, earning capacity and social worth. Progressive resistance training significantly improved the volunteers' strength, vitality, morale and ability to maintain social activities compared with the control group. 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.
Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts, Boston, MA
Maria A. Fiatarone, (617) 556-3075, fiatarone_ex@hnrc.tufts.edu

Equations used to estimate calories burned by adolescent females 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 eight and 17 years old. BMR accounts for 50 to 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 measurements, nine of the 10 equations evaluated significantly overestimated BMR in the black girls, and half overestimated BMR in the white girls. 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 researchers say ethnicity should be considered in future measurements of basal metabolic rate (BMR) and in refining equations used to estimate it.
Children's Nutrition Research Center, Houston, TX
William W. Wong,(713) 798-7168, wwong@bcm.tmc.edu

A couple drops of blood are all that's needed to accurately assess a person's natural ability to fight off infections or suppress 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 infection-fighting T-cells to multiply in whole blood--a familiar environment--rather than among foreign proteins now used to culture the T-cells. 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. Also, 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.
Beltsville Human Nutrition Research Center, Beltsville, MD
Tim R. Kramer, (301) 504-8396, kramer@307.usda.gov

Diets high in antioxidant foods appear to protect the brain against oxidative damage, if rat studies are any indication. Oxidative damage is thought to be the culprit behind age-related disfunctions such as loss of memory or motor coordination. In the studies, 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. Earlier, these foods scored highest among commonly eaten fruits and vegetables in a "test-tube assay" of total antioxidant capacity. The next step was to assess their protective power in animals. In the first test, 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. 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 responses of brain function controlling memory, movement and growth of nerve cells. Decline in all three functions due to oxygen exposure was significantly-- often dramatically--reduced by strawberry extract as well as by vitamin E. The scientists repeated the study using blueberry and spinach extracts. Preliminary data indicates that blueberry extract provides even more protection to rats' brains. Blueberries had the highest antioxidant capacity of the fruits and vegetables tested. If this finding holds up, it supports the usefulness of the chemical assay--known as ORAC--for identifying health-promoting foods.
Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts, Boston, MA
James A. Joseph, (617) 556-3178, joseph_ne@hnrc.tufts.edu

Girls and boys absorb two important bone-building minerals-- calcium and magnesium--from snap beans as easily as they absorb them from milk, according to recent findings. That's good news to researchers at the ARS center in Houston. They are 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. They also looked at magnesium absorption from snap beans and spinach. 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 from broccoli was about 5 percent higher. One cup of broccoli provides about one quarter as much calcium as a cup of milk. But the calcium in spinach was poorly absorbed because of a high content of absorption-blocking compounds known as oxylates. The youths absorbed magnesium from snap beans, spinach and milk at about the same rate. Snap beans provide nearly as much magnesium as milk, but spinach provides nearly five times more. In a related test, the researchers 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 discovery: The commercial snap bean variety "Hystyle" was among those with the highest calcium levels. In addition, the researchers found that younger, skinnier snap beans had significantly more calcium than older, fatter pods.
Children's Nutrition Research Center, Houston, TX
Steven Abrams/Michael Grusak, (713) 798-7000, sabrams@bcm.tmc.edu, mgrusak@bcm.tmc.edu

Older people whose heart rate soars and energy dives during aerobic exercise may want to take a closer look at their magnesium intake. A group of post-menopausal women experienced a significant drop in their work efficiency during a recent study in which 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. 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, suggesting that a significant number get well below that level. The study was the first to look at the effect of a low magnesium intake on the physiological function of people over age 55. It 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. But it's easy to get ample magnesium in a low-fat diet, the scientist said. Eat more vegetables, especially dark leafy greens, more whole wheat and other whole grain breads, cereals and pastas and more dried beans.
Grand Forks Human Nutrition Research Center, Grand Forks, ND
Henry C. Lukaski, (701) 795-8353, hlukaski@gfhnrc.ars.usda.gov

Last Updated: April 25, 1997
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