The study, “Effect of vitamin D on serum markers of bone turnover in SLE in a randomised controlled trial,” was published in the journal Lupus Science & Medicine.
Poor bone health is common among people living with SLE. Treatments (i.e., glucocorticoids) and features of the disease itself (i.e., ongoing inflammation and kidney damage) can have a negative impact on bones.
One strategy that has been proposed to help combat this is supplementation with vitamin D. This vitamin plays an important role in helping bones absorb calcium, and having too little of it is associated with poor bone health.
In the new study, researchers conducted a Phase 2 clinical trial (NCT00710021) to directly assess the effects of vitamin D supplementation on short-term bone health. To this end, 28 people with SLE were given the vitamin supplement, and 15 were given a placebo, for 12 weeks.
Participants were almost all female, their average age was 39 years, and the racial makeup of the group was mostly blacks and whites in about equal measure.
Because the researchers could not directly assess the health of bones (at least, not without invasive procedures), they instead measured the levels of propeptide of type 1 collagen (P1NP) and C-telopeptide (CTX). These are markers of bone formation and resorption, respectively.
The researchers expected that levels of both those markers would decrease following vitamin D supplementation; basically, this is because less bone resorption (essentially bone break down) is expected if more calcium is being absorbed by the bones.
However, there were no statistically significant differences between the placebo- and vitamin D-treated groups in either of these markers. This lack of association persisted after the researchers accounted for other factors, such as glucocorticoid use.
This result suggests that conventional medical wisdom about vitamin D supplementation in people with SLE may need to be re-evaluated. But the researchers recommended caution in interpreting the results; this is still a small, preliminary study and should be regarded as such.
“In this small randomized trial of vitamin D supplementation vs. placebo, we did not observe a difference in markers of bone turnover in the blood over 12 weeks,” Sara Tedeschi, MD, MPH, a professor at Harvard University and co-author of the study, said in a press release. “However, we were unable to study bone density or the risk of fractures due to the timeframe and study design. Also, all of the lupus participants in this study were required to have stable, relatively inactive lupus at the start of the study.”
“While we did not observe an effect of vitamin D on bone turnover markers in this small trial, it remains possible that vitamin D may impact bone turnover markers, bone density, and fracture risks in different subgroups of lupus patients — specifically young, pre-menopausal women with high lupus disease activity,” Tedeschi said.