January 31, 2011
Previously linked to the severity of
asthma and chronic obstructive pulmonary disease (COPD)
in humans, vitamin D deficiency has now been shown to alter lung
structure and function in young mice.
The new study, conducted by researchers
in Australia, offers the first concrete evidence linking vitamin D
deficiency with deficits in lung function and altered lung
The findings were published online ahead of the print edition of the
American Thoracic Society's American Journal of Respiratory and
Critical Care Medicine.
"The results of this study clearly
demonstrate that vitamin D deficiency alters lung growth,
resulting in lower lung volume and decrements in lung function,"
said Graeme Zosky, PhD, a research fellow at the Telethon
Institute for Child Health Research in Subiaco, Australia.
"This is the first direct
mechanistic evidence showing that vitamin D deficiency alters
lung development, which may explain the association between
obstructive lung disease and levels of vitamin D."
To conduct their study, the researchers
used a mouse model of vitamin D deficiency and evaluated lung
responses of two-week-old mice, comparing them to control mice
without vitamin D deficiency to determine what, if any, effects the
deficiency may have caused in the growth, structure or function of
Lung volume and lung function were evaluated using a
an instrument used to measure the amount of air in the lung, and via
forced oscillation, a technique used to measure the resistance to
air flow in the lungs.
Microscopic lung tissue samples were
also evaluated to assess changes in lung structure.
"The aim of this study was to
determine if vitamin D deficiency results in altered lung
function and/or structure as a potential explanation for the
association between vitamin D and chronic respiratory disease,"
said Dr. Zosky, who is also an adjunct senior lecturer at the
University of Western Australia's Centre for Child Health
"Specifically, we aimed to determine
if vitamin D deficiency has an influence on lung growth as
indicated by a decrease in lung volume. We also wanted to
determine if the deficiency alters the mechanical properties of
the lung tissue due to changes in the structure of the lung."
The researchers found that airway
resistance was significantly higher while lung volume was
significantly lower in vitamin D-deficient mice compared to control
mice. Examinations of specific tissue responses revealed model mice
had reduced lung function.
Lungs were also smaller in model mice,
which Dr. Zosky said could have been caused by the
deficiencies of the mother or of the offspring.
"Due to the nature of this study, we
were not able to determine whether the differences in lung size
and function we observed in the deficient offspring were the
result of their own deficient status or as a consequence of
developmental deficits that occurred in utero due to the
mother's deficiency," he said.
Dr. Zosky noted that although recent
studies suggest that vitamin D deficiency is associated with reduced
lung function, causal data confirming a relationship between vitamin
D and lung function have been lacking.
"For the first time, we have
demonstrated a direct role for vitamin D in causing decreased
lung function in the absence of known confounders such as
physical inactivity, confirming the assertion by epidemiological
studies that there is a relationship between vitamin D
deficiency and lung function," Dr. Zosky said.
"The differences we observed in lung
volume and lung mechanics, which were substantial and
physiologically relevant, raise serious concerns regarding the
increased prevalence of vitamin D deficiency in communities
around the world. The results also raise concerns about the
potential this deficiency may have on lung health, and in
particular, the potential impact deficiency may have on the
susceptibility to obstructive lung disease."
Dr. Zosky said the study results have
important implications for prevention of lung diseases in
populations where vitamin D deficiencies are common.
Future studies need to be conducted to
determine whether vitamin D deficiency-induced alterations in lung
growth increase the severity of obstructive lung disease and to
identify susceptible populations whose use of dietary vitamin D
supplementation could be used to improve lung health outcomes, he
A daily dose for treatment of deficiency would be 10,000 units
calciferol, the form of Vitamin D
found in supplements. A daily dose for prevention would be 400
units, the amount found in most overthecounter supplements. Do not
take high doses without consulting your doctor, as there is a risk
Vitamin D comes from UVB light on our skin but in winter very little
UVB radiation reaches the Earth's surface. No Vitamin D is made in
the skin of people living at latitudes above or below about 35
degrees between September and April.
It is very important, particularly for children and pregnant women,
to have good Vitamin D levels as it is needed for healthy growth.
Research last year suggested Vitamin D was also important for
protection against cancer. Those with Vitamin D levels of less than
ten will have quite marked symptoms of tiredness and bone pain,
particularly in the shins.
Very few foods contain Vitamin D. Liver, oily fish, egg yolk and
sun-dried mushrooms are pretty much
the only ones. Mushrooms contain
ergocalciferol, which is a
precursor to Vitamin D, and when they are exposed to sunlight they
make large quantities of it.
There is no doubt that the use of sunscreen and cosmetics with UV
block is associated with some of the Vitamin D deficiencies.