|
Nearly 80 million Americans would no longer need to
take vitamin D supplements under new Institute of
Medicine guidelines, according to a study by Loyola
University Chicago Stritch School of Medicine
researchers.
The new guidelines advise that almost all people get
sufficient vitamin D when their blood levels are at
or above 20 nanograms per milliliter (ng/ml). Older
guidelines said people needed vitamin D levels above
30 ng/ml.
Holly Kramer, MD, MPH and colleagues examined data
from 15,099 non-institutionalized adults who
participated in the Third National Health and
Nutrition Examination Study (NHANES III). The sample
included 1,097 adults who had chronic kidney
disease, which has been linked to low vitamin D
levels.
The Institute of Medicine committee found that
vitamin D is essential to avoid poor bone health,
such as rickets. But there have been conflicting and
mixed results in studies on whether vitamin D can
also protect against cancer, heart disease,
autoimmune diseases and diabetes, the Institute of
Medicine committee found.
Moreover, excessive vitamin D can damage the kidneys
and heart, the committee reported.
In the survey population, 70.5 percent of adults
with healthy kidneys had vitamin D blood levels that
would be considered insufficient under the older
guidelines. But under the newer Institute of
Medicine guidelines, only 30.3 percent of these
adults had insufficient vitamin D levels.
Among adults with chronic kidney disease, 76.5
percent had insufficient vitamin D under the older
guidelines, while only 35.4 percent had insufficient
levels under the Institute of Medicine guidelines.
Because NHANES III is a representative sample,
researchers were able to extrapolate results to the
general population. Kramer and colleagues estimate
that a total of 78.7 million adults considered to
have insufficient vitamin D levels under the older
guidelines would now have sufficient levels under
the Institute of Medicine guidelines. "The new
guidelines have an impact on a large proportion of
the population," Kramer said.
The Institute of Medicine guidelines are based on
nearly 1,000 published studies and testimony from
scientists and other experts. (The Institute of
Medicine committee that wrote the new guidelines for
vitamin D and calcium includes Ramon Durazo-Arvizu,
PhD, a professor in Loyola's Department of
Preventive Medicine and Epidemiology).
However, the Institute of Medicine guidelines are
controversial. For example, the Endocrine Society
continues to endorse the older guidelines. Kramer
said that people who are confused about how much
vitamin D they need should consult with their
doctors.
Kramer is first author of the study, which was
funded by the National Institutes of Health. She is
an associate professor in Loyola's Department of
Preventive Medicine and Epidemiology and Department
of Medicine, Division of Nephrology and
Hypertension. Her co-authors are Durazo-Arvizu;
Guichan Cao, MS; Amy Luke, PhD; David Shoham, PhD;
and Richard Cooper, PhD of Loyola's Department of
Preventive Medicine and Epidemiology and Chris
Sempos, PhD of the National Institutes of Health's
Office of Dietary Supplements.
For more information
Results were published Oct. 24, 2012 in the journal
PLOS ONE
"Mortality Rates Across 25-Hydroxyvitamin D
(25[OH]D) Levels among Adults with and without
Estimated Glomerular Filtration Rate <60 ml/min/1.73
m2: The Third National Health and Nutrition
Examination Survey".
http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0047458
Loyola University Health System
MDN)
|
