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| Credit: znn.india.com |
About 70 percent of Americans, and
up to a billion people worldwide, have insufficient levels of vitamin D. OSU's
Linus Pauling Institute recommends adults take 2,000 IU of supplemental vitamin
D daily. The current federal guidelines are 600 IU for most adults, and 800 for
those older than 70.
A
new study concludes that among older adults -- especially those who are frail*
-- low levels of vitamin D can mean a much greater risk of death.
Overall,
the randomized, nationally representative study found that people who were
frail had more than double the risk of death than those who were not frail.
Frail adults with low levels of vitamin D tripled their risk of death over
people who were not frail and who had higher levels of vitamin D.
"What
this really means is that it is important to assess vitamin D levels in older
adults, and especially among people who are frail," said lead author Ellen
Smit.
Smit
said past studies have separately associated frailty and low vitamin D with a
greater mortality risk, but this is the first to look at the combined effect.
"Older
adults need to be screened for vitamin D," said Smit, who is a nutritional
epidemiologist at Oregon State University (OSU) College of Public Health and Human
Sciences. Her research is focused on diet, metabolism, and physical activity in
relation to both chronic disease and HIV infection.
"As
you age, there is an increased risk of melanoma, but older adults should try
and get more activity in the sunshine," she said. "Our study suggests
that there is an opportunity for intervention with those who are in the
pre-frail group, but could live longer, more independent lives if they get
proper nutrition and exercise."
Because
of the cross-sectional nature of the survey, researchers could not determine if
low vitamin D contributed to frailty, or whether frail people became vitamin D
deficient because of health problems. However, Smit said the longitudinal
analysis on death showed it may not matter which came first.
"If
you have both, it may not really matter which came first because you are worse
off and at greater risk of dying than other older people who are frail and who
don't have low vitamin D," she said. "This is an important finding
because we already know there is a biological basis for this. Vitamin D impacts
muscle function and bones, so it makes sense that it plays a big role in
frailty."
This
study examined more than 4,300 adults older than 60 using data from the Third
National Health and Nutrition Examination Survey. Participants were divided
people into four groups. The low group had levels less than 50 nanograms per
milliliter; the highest group had vitamin D of 84 or higher. In general, those
who had lower vitamin D levels were more likely to be frail.
"We
want the older population to be able to live as independent for as long as
possible, and those who are frail have a number of health problems as they
age," Smit said. "A balanced diet including good sources of vitamin D
like milk and fish, and being physically active outdoors, will go a long way in
helping older adults to stay independent and healthy for longer."
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###
*Frailty
is when a person experiences a decrease in physical functioning characterized
by at least three of the following five criteria: muscle weakness, slow
walking, exhaustion, low physical activity, and unintentional weight loss.
People are considered "pre-frail" when they have one or two of the
five criteria.
The
above story is based on the July 26, 2012 news release by Oregon State University.
The
research has been published ahead of print June 13, 2012 in the European
Journal of Clinical Nutrition:
Smit
E, Crespo CJ, Michael Y, Ramirez-Marrero FA, Brodowicz GR, Bartlett S, Andersen
RE. The effect of vitamin D and frailty
on mortality among non-institutionalized US older adults. Eur J Clin Nutr., 2012; DOI:
10.1038/ejcn.2012.67
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