Researchers from the University of Auckland
examined the relationship between vitamin D
and lung function using participants from
the United States National Health and
Nutrition Examination Survey (NHANES III)
carried out during 1988 to 1994.
The study included 14,091 people aged >= 20
years, who were interviewed at mobile
examination centers, had spirometry
performed, and had serum 25-hydroxyvitamin D
measured.
Vitamin D measurements were divided into
five groups (quintiles), ranging from more
than 85.7 mL to less than 40.4 mL.
After adjusting for gender, age, ethnicity,
body mass index, and smoking status, the
differences between the lowest quintile of
vitamin D and the next quintile were 79 mL
for FEV1 and 71 mL for FVC.
In comparison, the differences between the
highest and lowest quintiles of vitamin D
were 126 mL for FEV1 and 172 mL for FVC.
With further adjustment for physical
activity, intake of vitamin D supplements
and milk, and antioxidant level, the
difference between the highest and lowest
quintiles of vitamin D also was significant
at 106 mL for FEV1 and 142 mL for FVC.
"The difference in lung function between the
highest and lowest quintiles of vitamin D is
substantial and greater than the difference
between former and nonsmokers," said Dr.
Black.
"Although there is a definite relationship
between lung function and vitamin D, it is
unclear if increases in vitamin D through
supplements or dietary intake will actually
improve lung function in patients with
chronic respiratory diseases."
Overall, male gender, younger age, white
ethnicity, nonsmoking status, and regular,
vigorous physical activity were associated
with the highest lung function. Vitamin D
was higher in men than women, was inversely
related to BMI, and declined with age.
Vitamin D also was lower in non-Hispanic
blacks and Mexican-Americans, compared with
non-Hispanic whites, and it was lower in
participants smoking more than 20 cigarettes
a day compared with nonsmokers.
"Vitamin D would be a relatively simple,
low-cost intervention that would likely have
high compliance to prevent or slow loss of
lung function in susceptible subgroups.
"However,
further studies examining the relationship
between vitamin D and lung function are
warranted to identify who may benefit from
such an intervention," said author of the
study's corresponding editorial Rosalind
Wright, MD, MPH, Channing Laboratory,
Department of Medicine, Brigham and Women's
Hospital, Harvard Medical School, Boston,
MA.
"Chronic lung conditions compromise quality
of life for millions of people in the United
States and around the world," said W.
Michael Alberts, MD, FCCP, President of the
American College of Chest Physicians. "By
understanding the effect that vitamins have
on lung function, we may be able to identify
new and more effective treatments for these
debilitating diseases."
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