That's based on lab tests done on cells, as well as a brief experiment with a small group of asthma patients.
Vitamin D might also help treat other diseases involving inflammation and the immune system, write the researchers. However, their study doesn't include any recommendations about taking vitamin D supplements.
The asthma experts who led the study included Catherine Hawrylowicz, PhD, of King's College London.
The study focused on asthma that doesn't respond to steroid treatments.
Steroids help many people manage their asthma. Most asthma patients take their steroids through inhaled medications.
Others must take steroid pills to control their asthma, especially during acute attacks. Some of those patients don't respond to steroids. That limits their treatment options.
Testing Vitamin D
The form of vitamin D used in this study was calcitriol, or vitamin D-3. It's the form of vitamin D that the body uses. It's also the type found in many vitamin supplements.
First, the researchers took blood samples from a small group of people with and without steroid-resistant asthma.
The scientists studied the patients' T-cells, which are made by the immune system. The T-cells of people with steroid-resistant asthma weren't up to par in producing a chemical called IL-10. That chemical helps tame immune responses tied to asthma and allergies.
Next, the scientists exposed the T-cells to vitamin D-3. When that happened, the T-cells were more sensitive to steroids and boosted production of IL-10.
No breathing tests or patient surveys were done to see if people breathed better or wheezed less.
"The hope is that this work will lead to new ways to treat people who don't respond to steroid treatment as it currently stands," Hawrylowicz says, in a news release.
"It could also help those people who are on heavy doses of steroids to reduce the amount of medication they are taking," she says.