UNMC study shows vitamin D protects bones in mice exposed to agricultural dust; may have implications for agricultural workers

You've probably heard it a thousand times - drink your milk. In the future, you may also hear - take your vitamin D.

A small study led by the University of Nebraska Medical Center found evidence that may contribute to the growing knowledge of benefits of vitamin D.

Researchers found that mice exposed to hog barn dust over three weeks had a statistically significant reduction of bone loss - 5 to 20 percent. But they had no bone loss if they received a high dose supplementation of vitamin D.

It's well known that agriculture workers have high rates of airway inflammatory diseases including asthma-like disorders and chronic bronchitis and high rates of musculoskeletal diseases, including bone fractures.

One of the study goals was to see if high dose supplementation of vitamin D would help protect against the adverse outcomes due to inhaling dusts in the agricultural environment. Though they did find a slight effect on reducing inflammation in the lungs of mice, they found a statistically significant effect on protecting the bones.

"We found if we gave vitamin D, the mice didn't get bone loss," said Jill Poole, M.D., associate professor in the UNMC Department of Internal Medicine and principal investigator of the study published in the scientific journal, Immunology Research. "There was some benefit of reducing inflammation in their lungs, but it completely protected their bones. This is important because emerging data in humans suggests that generalized chronic lung inflammation is a risk factor for osteoporosis and fractures."

Dr. Poole said she was surprised to see that lung inflammation can cause such profound bone changes.

"In the study we controlled for diet in the mice," she said. "We know vitamin D helps bones, but it also appears to help bones in the presence of inflammation, and it had a direct effect on the bones.

"Vitamin D changes molecules that respond to the dust, and through this response, we think vitamin D may be helpful in lessening bone loss brought on by agricultural dust. My goal is to find therapies that farmers can use to reduce the consequences of agricultural dust exposure and improve their health. Musculoskeletal problems are huge."

Dr. Poole's message to those who work in agricultural dust environments is wear a protective respiratory equipment.

Although the study is limited because it involved mice and didn't measure exposure over a long period of time, Dr. Poole suggests taking vitamin D.

"As a bone protective strategy, people particularly with underlying respiratory disorders and symptoms, might want to consider taking over-the-counter supplemental vitamin D3 - 2,000 to 4,000 IUs daily as long as they don't have any other health problems," she said. "If they do have health problems, they should first talk to their doctor before taking the vitamin."

Dr. Poole said the mouse model in the study is the first animal model linking inhalant agriculture organic dusts to causing systemic bone deterioration.

Studies in humans are warranted to determine vitamin D levels in agricultural workers, and if vitamin D supplementation could improve health outcomes, she said.

Collaborators included a multidisciplinary team of UNMC and VA Nebraska-Western Iowa Health Care System researchers. Researchers included: Anand Dusad, M.D., Michael Duryee; Lynell Klassen, M.D., Ted Mikuls, M.D., Deb Romberger, M.D., Elizabeth Staab, Geoffrey Thiele, Ph.D., Todd Wyatt, Ph.D., Dong Wang, Ph.D., William West, M.D., and Stephen Reynolds, Ph.D., Colorado State University in Fort Collins.