Low Vitamin D Levels Linked To Poor
Physical Performance In Older Adults
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
"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
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,"
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,"
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