Veel ouderen krijgen te weinig vitamine D en daardoor een slechtere motoriek.*
Ouderen die niet voldoende vitamine D, in de voeding of van de zon, innemen hebben meer kans op verminderde spierkracht en motoriek. Dit blijkt uit een Italiaans-Amerikaanse studie onder duizend Italiaanse ouderen met een gemiddelde leeftijd van 75 jaar. Ongeveer 25% van de mensen ouder dan 60 jaar hebben een duidelijk vitamine D tekort. Omdat niet de oorzaak onderzocht is zou het ook kunnen zijn dat omdat veel ouderen minder mobiel zijn en daardoor minder in de zon komen, daardoor lagere vitamine D bloedwaarden hebben. De huid van ouderen kan al minder vitamine D aanmaken uit zonlicht. Uit steeds meer onderzoek wordt het duidelijk dat voldoende bloedwaarde vitamine D niet alleen meer belangrijk zijn voor goede botten doch ook tegen diabetes, verkoudheden, tbc en kanker. Het is daarom de vraag of de nu geldende aanbevelingen voor vitamine D niet veel te laag zijn.
Poor
Physical Performance In Older Adults Linked To Low Vitamin D Levels
Older
adults who don't get enough vitamin D - either from their diets or exposure to
the sun - may be at increased risk for poor physical performance and disability,
according to new research from Wake Forest University School of Medicine and
colleagues.
"With a growing older population, we need to identify better ways to reduce
the risk of disability," said lead author Denise Houston, Ph.D. "Our
study showed a significant relationship between low vitamin D levels in older
adults and poorer physical performance."
The results are reported in the Journal of Gerontology: Medical Sciences.
About one-fourth of people over age 60 have low vitamin D levels. Previous
research has shown that vitamin D not only plays a role in bone health, but
possibly also in protecting against diabetes, cancer, colds and tuberculosis.
"Recent findings showing the importance of vitamin D status on multiple
health outcomes underscore the need for more research on the effects of low
vitamin D levels in elderly populations," said Houston, an instructor in
internal medicine - gerontology.
Vitamin D is naturally produced when skin is exposed to the sun's ultraviolet
rays. Foods such as fortified milk, juice and cereals also contain vitamin D,
but it is difficult to get enough through diet alone, said Houston.
Older adults are particularly prone to low vitamin D levels because they may get
less exposure to sunlight and because their skin is less efficient in producing
vitamin D from sun exposure compared to younger adults. Older adults also may
not get enough vitamin D from dietary sources.
"There is a growing awareness that the prevalence of low vitamin D levels
is common among the elderly," said Houston.
For the current study, researchers analyzed data from the InCHIANTI study, which
evaluated factors contributing to the decline of mobility in late life. The
study involved 976 people who were 65 years and older from two towns in the
Chianti area of Italy. The mean age of participants was 74.8 years. Data were
collected from Sept. 1998 through March 2000.
Participants completed a short physical performance test of their walking speed,
ability to stand from a chair and ability to maintain their balance in
progressively more challenging positions. In addition, handgrip strength, a
predictor of future disability, was measured using a hand-held dynamometer.
The researchers found that physical performance and grip strength were about
five to 10 percent lower in those who had low levels of vitamin D. After looking
at other variables that could influence the results, such as body mass index,
physical activity, the season of the year, mental abilities, health conditions
and anemia, the results held true.
The study wasn't designed to evaluate whether low vitamin D levels actually
cause poor physical performance, but the results suggest the need for additional
research in this area, said Houston. She said vitamin D plays an important role
in muscle function, so it is plausible that low levels of the vitamin could
result in lower muscle strength and physical performance.
"But it's also possible that those with poor physical performance had less
exposure to sunlight resulting in low vitamin D levels," she said.
Current recommendations call for people from age 50 to 69 to get 400
international units (IUs) of vitamin D per day and for those over age 70 to get
600 IUs. Many researchers, however, suggest that higher amounts may be needed.
"Higher amounts of vitamin D may be needed for the preservation of muscle
strength and physical function as well as other conditions such as cancer
prevention," said Houston. "The current recommendations are based
primarily on vitamin D's effects on bone health."
###
The research is supported by the Italian Ministry of Health and in part by the
National Institute on Aging. Co-researchers were Gary Schwartz, Ph.D., and
Stephen Kritchevsky, Ph.D., both with Wake Forest, Matteo Cesari, M.D., Ph.D,
with the University of Florida, Luigi Ferrucci, M.D., Ph.D., with the National
Institute on Aging, Dario Maggio, M.D., and Antonio Cherubini, M.D., Ph.D, both
with the University of Perugia in Italy, Mary Ann Johnson, Ph.D., with the
University of Georgia, and Benedetta Bartali, R.D., with Cornell University.
Wake Forest University Baptist Medical Center is an academic health system
comprised of North Carolina Baptist Hospital and Wake Forest University Health
Sciences, which operates the university's School of Medicine. U.S. News &
World Report ranks Wake Forest University School of Medicine 18th in family
medicine, 20th in geriatrics, 25th in primary care and 41st in research among
the nation's medical schools. It ranks 35th in research funding by the National
Institutes of Health. Almost 150 members of the medical school faculty are
listed in Best Doctors in America.
(Mei 2007)