Low Blood Levels of Vitamin D Linked to Increased Risk of Interstitial Lung Disease
An estimated 20,000 individuals are diagnosed with interstitial lung disease (IDL) each year, which is characterized by lung scarring and inflammation that leads to progressive, disabling and irreversible lung damage. After analyzing the medical information of more than 6,000 adults over a 10-year period, Johns Hopkins researchers discovered that low blood levels of vitamin D were associated with an increased risk of early signs of ILD.
Researchers analyzed a series of studies to discover new, potentially treatable, factors related to early signs of the disease. For instance, CT scans may reveal abnormalities that are present before symptoms develop, which, in turn, can help to support future preventive strategies. The results of the most recent data analysis, which were published in the Journal of Nutrition, suggest that low vitamin D might be one factor involved in developing interstitial lung disease.
"We knew that the activated vitamin D hormone has anti-inflammatory properties and helps regulate the immune system, which goes awry in ILD," says Erin Michos, M.D., M.H.S., associate professor of medicine at the Johns Hopkins University School of Medicine and associate director of preventive cardiology at the Johns Hopkins Ciccarone Center for the Prevention of Cardiovascular Disease. "There was also evidence in the literature that vitamin D plays a role in obstructive lung diseases such as asthma and COPD, and we now found that the association exists with this scarring form of lung disease too."
Researchers used data from the Multi-Ethnic Study of Atherosclerosis (MESA), which recruited more than 6,800 individuals throughout the U.S. Throughout the participants' initial clinical visit, the medical staff took blood samples and measured, among other things, vitamin D levels. Participants also underwent heart CT scans throughout the study, which provided both incidental and partial views of the lungs. After ten years, 2,668 participants were given full lung CT scans evaluated for the prevalence of scar tissue or other abnormalities.
Patients with vitamin D-deficiency were documented to have had a larger volume of bright spots in the lung suggestive of damaged lung tissue. After reviewing the data from the full lung scans, researchers discovered that those with deficient or intermediate vitamin D levels had a 50 to 60 higher rate of abnormalities on their full lung scans that suggested early signs of ILD. Further, these associations were still prevalent even after adjusting for additional cardiovascular and inflammatory risk factors, including high blood pressure and cholesterol, diabetes and levels of high-sensitivity C-reactive protein.
"Our study suggests that adequate levels of vitamin D may be important for lung health. We might now consider adding vitamin D deficiency to the list of factors involved in disease processes, along with the known ILD risk factors such as environmental toxins and smoking," says Michos. "However, more research is needed to determine whether optimizing blood vitamin D levels can prevent or slow progression of this lung disease."
