Contact: Sue McGreevey
Massachusetts General Hospital
Vitamin D deficiency may increase risk of colds, flu
Large-scale study supports potential role in boosting immune system, more research needed
D may be an important way to arm the immune system against disorders
like the common cold, report investigators from the University of
Colorado Denver (UC Denver) School of Medicine, Massachusetts General
Hospital (MGH) and Children's Hospital Boston.
In the largest and most nationally representative study of the
association between vitamin D and respiratory infections, people with
the lowest blood vitamin D levels reported having significantly more
recent colds or cases of the flu. The risks were even higher for those
with chronic respiratory disorders, such as asthma and emphysema. The
report appears in the February 23
Archives of Internal Medicine.
findings of our study support an important role for vitamin D in
prevention of common respiratory infections, such as colds and the
flu," says Adit Ginde, MD, MPH, UC Denver Division of Emergency
Medicine and lead author of the study. "Individuals with common lung
diseases, such as asthma or emphysema, may be particularly susceptible
to respiratory infections from vitamin D deficiency."
vitamin C has been used for the prevention of colds and other
respiratory disorders for decades, little scientific evidence supports
its effectiveness. In contrast, in recent years evidence has
accumulated that vitamin D – most commonly associated with the
development and maintenance of strong bones – may also play a key role
in the immune system. Circumstantial evidence has implicated the
wintertime deficiency of vitamin D, which the body produces in response
to sunlight, in the seasonal increase in colds and flu; and small
studies have suggested an association between low blood levels of
vitamin D and a higher risk of respiratory infections.
current study analyzed data from the Third National Health and
Nutrition Examination Survey (NHANES III), conducted by the National
Center for Health Statistics. Participants were interviewed in their
homes regarding their health and nutrition, and most participants also
received a physical examination that included collection of blood and
other samples for laboratory analysis. The research team analyzed blood
levels of 25-hydroxyvitamin D (25OHD) – the best measure of vitamin D
status – from almost 19,000 adult and adolescent NHANES III
participants, selected to be representative of the overall U.S.
Study participants with the lowest vitamin D blood
levels – less than 10 ng per milliliter of blood – were about 40
percent more likely to report having a recent respiratory infection
than were those with vitamin D levels of 30 or higher. The association
was present in all seasons and even stronger among participants with a
history of asthma or chronic obstructive pulmonary disease (COPD),
including emphysema. Asthma patients with the lowest vitamin D levels
were five times more likely to have had a recent respiratory infection;
while among COPD patients, respiratory infections were twice as common
among those with vitamin D deficiency.
infection in someone with otherwise healthy lungs usually causes a few
days of relatively mild symptoms," explains Carlos Camargo, MD, DrPH,
MGH Department of Emergency Medicine and senior author of the study.
"But respiratory infections in individuals with an underlying lung
disease can cause serious attacks of asthma or COPD that may require
urgent office visits, emergency department visits or hospitalizations.
So the impact of preventing infections in these patients could be very
The authors stress that the study's results need to
be confirmed in clinical trials before vitamin D can be recommended to
prevent colds and flu. "We are planning clinical trials to test the
effectiveness of vitamin D to boost immunity and fight respiratory
infection, with a focus on individuals with asthma and COPD, as well as
children and older adults – groups that are at higher risk for more
severe illness," Ginde says. "While it's too early to make any
definitive recommendations, many Americans also need more vitamin D for
its bone and general health benefits. Clinicians and laypeople should
stay tuned as this exciting area of research continues to expand."
is an assistant professor of Surgery at UC Denver School of Medicine,
and Camargo is an associate professor of Medicine at Harvard Medical
School. Jonathan Mansbach, MD, of Children's Hospital Boston is a
co-author of the
Archives of Internal Medicine report. The
study was supported by grants from the National Institutes of Health,
the National Heart, Lung and Blood Institute, and the MGH Center for
D-receptor Activation Research.
The University of Colorado Denver School of Medicine (http://www.uchsc.edu/som/)
faculty work to advance science and improve care as the physicians,
educators and scientists at University of Colorado Hospital, The
Children's Hospital, Denver Health, National Jewish Health, and the
Denver Veterans Affairs Medical Center. Degrees offered by the UC
Denver School of Medicine include doctor of medicine, doctor of
physical therapy, and masters of physician assistant studies. The
School is part of the University of Colorado Denver (http://www.uchsc.edu/), one of three campuses in the University of Colorado system.
Massachusetts General Hospital (http://www.massgeneral.org/),
established in 1811, is the original and largest teaching hospital of
Harvard Medical School. The MGH conducts the largest hospital-based
research program in the United States, with an annual research budget
of more than $500 million and major research centers in AIDS,
cardiovascular research, cancer, computational and integrative biology,
cutaneous biology, human genetics, medical imaging, neurodegenerative
disorders, regenerative medicine, systems biology, transplantation
biology and photomedicine.