In the first study of its kind, results of a University of Nebraska Medical Center research study suggest that vitamin D may be important for humans exposed to agricultural organic dust. In the study, researchers found a significant decrease in lung inflammation in mice exposed to hog barn dust that received high doses of vitamin D.

"We found that the relatively high vitamin D treatment group had significantly decreased lung inflammation. The mice still got inflammation but didn't get it as bad," said Jill Poole, M.D., associate professor in the UNMC Department of Internal Medicine and principal investigator of the study.

Past studies in the U.S. have shown relationships with vitamin D and various airway inflammatory diseases such as asthma and chronic obstructive pulmonary disease (COPD).

"We know that vitamin D changes the expression of key molecules that respond to the dust, and through this response, we think vitamin D may be helpful in lessening disease brought on by agricultural dust," Dr. Poole said.

Workers on today's farms are exposed to a variety of high levels of agricultural organic dust - dust that comes from feed, bedding and livestock, which includes mold, pollen, bacteria, pesticides, and chemicals. Exposure can lead to inflammation in the lungs and a risk of developing COPD.

Over time, exposure to organic dust can result in serious respiratory illnesses, such as organic dust toxic syndrome (ODTS) and Farmer's lung.

Dr. Poole said initial exposure in humans to organic dust induces an intense airway inflammatory response that wanes over time, but repetitive exposure causes an increased risk of lung function decline, persistent inflammation and progressive respiratory impairment.

Researchers used unique mouse models that were exposed to hog barn dust. One group received a high vitamin D diet and the other a low vitamin D diet.

Though there are a lot of things researchers still need to figure out, based on the initial findings in mice, Dr. Poole hopes that those with or without lung disease exposed to agricultural dust consider taking vitamin D. She also recommends they ask primary care providers to check vitamin D levels to find out if they are deficient.

"Since vitamin D is inexpensive, readily available and safe, if you don't take more than 4,000 IUs daily, there's no downside," she said. "We're learning more and more about vitamin D and its benefits for a variety of health issues.

"I think there should be awareness in the farming community about the potential benefit of vitamin D. How important it is for sure we don't know yet. But it may help the immune system."

The study, published in the Journal of Biochemical and Molecular Toxicology, was funded by the National Institute of Health Institute of Environmental Health Sciences and the National Institute for Occupational Safety and Health (NIOSH) Agricultural Safety and Health Center at the UNMC College of Public Health.

Dr. Poole said limitations of the study were it involved mice, not humans, and the study didn't measure exposure over a long period of time. She said more studies in humans are warranted to determine vitamin D levels in farmers and if vitamin D supplementation could improve health outcomes.

Other UNMC researchers in the study included: lead author, Gregory Golden, M.D., Todd Wyatt, Ph.D., Deb Romberger, M.D., Daniel Reiff, Michael McCaskill, Ph.D., Christopher Bauer, and Angela Gleason.