Is vitamin D deficiency to blame for lung disease?

As the summer advances, make sure you make the most of the sunny days and boost your vitamin D levels; this nutrient is tied to many important aspects of health. Recent research has now even found a link between low vitamin D levels and interstitial lung disease.

Interstitial lung disease (ILD) refers to a series of serious lung problems that affect the function of this respiratory organ.

These problems worsen easily, and they may cause irreversible damage that shortens a person's life expectancy.

That is why a team at Johns Hopkins Medicine in Baltimore, MD, has been exploring several modifiable risk factors for this condition.

The scientists hope that they would be able to identify viable preventive measures that could be implemented fairly easily.

The team was able to verify that people with low to intermediate blood levels of vitamin D were more severely exposed to ILD than peers with recommended levels of this crucial nutrient.

The results of this study were published yesterday in the Journal of Nutrition.

Low vitamin D tied to lung damage

Dr. Erin Michos — who's an associate professor of medicine at the Johns Hopkins University School of Medicine — and colleagues reviewed the medical data of 6,302 study participants initially recruited for the Multi-Ethnic Study of Atherosclerosis.

Most of these participants (53 percent) were women, and they were aged 62, on average. In the cohort, 38 percent of people were white, 28 percent were African-American, 22 percent were Hispanic, and the remaining 12 percent were of Chinese descent.

The participants were followed up over 10 years, and blood samples were collected at intervals. Dr. Michos and team looked out for a marker of vitamin D called 25-hydroxyvitamin D (25[OH]D).

Everyone who had under 20 nanograms per milliliter of 25(OH)D at baseline was considered to be vitamin D deficient — and the numbers added up to 2,051 people with such low levels.

Participants who had 20–30 nanograms per milliliter of the vitamin D biomarker were considered as having intermediate levels of the vitamin, and those with 30 nanograms per milliliter or more were deemed to have optimal vitamin D levels.

At baseline, as well as at various points during this study, all the participants were given CT scans of the heart — since the Multi-Ethnic Study of Atherosclerosis was primarily concerned with cardiovascular health — which also showed part of these individuals' lungs.

After 10 years from the time of registration, 2,668 participants were also given full lung CT scans that were analyzed for signs of lung damage or abnormalities.

The researchers found that those with low, or even intermediate, levels of vitamin D had a higher risk of showing early signs of ILD.

"We knew that the activated vitamin D hormone has anti-inflammatory properties and helps regulate the immune system, which goes awry in ILD," explains Dr. Michos.

"There was also evidence in the literature that vitamin D plays a role in obstructive lung diseases such as asthma and [chronic obstructive pulmonary disease]," she adds, "and we now found that the association exists with this scarring form of lung disease too."

'Vitamin D important for lung health'

The researchers noted that the lung CT scans of the participants who lacked appropriate levels of vitamin D showed a greater amount of spots indicative of damaged tissue, when compared with those of participants with optimal vitamin D levels.

These findings remained valid, even after the researchers adjusted their analysis to account for potential modifying factors, such as age, smoking habits, obesity, or lack of regular exercise.

Moreover, the vitamin D-deficient participants were also 50–60 percent more likely than participants with healthy blood levels of this nutrient to shown early signs of ILD.

"Our study suggests that adequate levels of vitamin D may be important for lung health."

Dr. Erin Michos

"We might now consider," she continues, "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."

Though Dr. Michos and colleagues explain that their study only indicates an association and cannot yet speak of a clear cause-and-effect relationship, they believe that additional research should dive deeper to confirm whether optimal vitamin D levels could protect people against the onset of lung disease, which is currently an incurable condition.

"[M]ore research is needed to determine whether optimizing blood vitamin D levels can prevent or slow progression of this lung disease," Dr. Michos notes.

Boosting vitamin D levels is an easy preventive measure, requiring only minor lifestyle adjustments, such as spending more time in natural sunlight and eating foods that are rich in this nutrient, such as fatty fish including salmon and mackerel.