As we have reported often, studies suggest vitamin D has anti-inflammatory as well as immunomodulatory effects, implying a probable role in autoimmune disorders. Among the autoimmune diseases associated with vitamin D deficiency, the link has been particularly strong for Systemic lupus erythematosus (SLE). Dr Daniel Birmingham and colleagues found that large seasonal declines in vitamin D status may trigger SLE flare ups in non-African Americans (non-AAs).
Birmingham DJ, Hebert LA, Song H, Noonan WT, Rovin BH, Nagaraja HN, Yu CY. Evidence that abnormally large seasonal declines in vitamin D status may trigger SLE flare in non-African Americans. Lupus. Jan 2012.
The authors collected data from the Ohio SLE Study (OSS), a prospective study of 106 recurrently active SLE patients. To assess changes in vitamin D levels, 25(OH)D assays were performed for serum samples collected 4 and 2 months prior to flare and at the time of flare (-4, -2, 0), the authors call this 4 month period a “flare interval.” The authors tested 82 flare intervals from 46 patients.
The authors stratified the data by race and whether the flare occurred during a low daylight month (LDM – October through March) or high daylight month (HDM – April through September). They found:
Birmingham and colleagues also compared flare intervals and no-flare intervals in equivalent non-AA participants during corresponding LDM months. They found:
The authors conclude:
“…The present work is consistent with the hypothesis that during LDM, a larger than usual decline in vitamin D status is a mechanism of SLE flare. The mechanism may involve a reduction in the roles played by vitamin D in modulating both the immune response and the inflammatory response.”
They state to further support their hypothesis future research requires a randomized controlled trial, controlling for skin color and seasonality. One such trial is currently under way. In the meantime, the Vitamin D Council believes that current research suggests it’s better to be sufficient than deficient.