A retrospective study published in Menopause examined how serum vitamin D concentration affects lumbar disc degeneration (LDD) and low back pain (LBP) in postmenopausal women. The researchers concluded that vitamin D deficiency was correlated with both LDD and LBP in this population.
Women were enrolled between July 2017 and December 2018. Electrochemiluminescence assays were used to measure serum concentrations of bone turnover markers, and the Pfirrmann grading system was implemented to determine disc degeneration. Patient surveys were used to gather additional relevant data. Severe vitamin D deficiency was defined as a serum 25(OH)D concentration <10 ng/mL, and normal vitamin D status was defined as a serum 25(OH)D concentration >30 ng/mL). A total of 232 women were enrolled in the study.
The mean age of the study population was 65.6±10.1 years; mean 25-hydroxyvitamin D (25[OH]D) concentrations were 19.38±9.21 ng/mL. Overall, 12.9% of participants had a severe vitamin D deficiency, and 12.5% had normal vitamin D status. Compared to the other groups, the severe vitamin D deficiency group had higher visual analog scale scores for LBP (P=0.002) and lower bone mineral density T scores (P=0.004). a significant relationship was observed between severe vitamin D deficiency and more severe LDD in the lumbosacral region (L4-S1, L1-S1; P<0.05), but this was not as pronounced in the upper lumbar region. Vitamin D concentration was inversely associated with disc degeneration severity (L2-L3, L4-S1, L1-S1; P<0.05). When adjusting for confounders, the following factors were correlated with higher incidence of moderate-to-severe pain: smoking, vitamin D deficiency, lack of vitamin D supplementation, high body mass index, and low bone mineral density T score.
“Vitamin D deficiency is associated with LDD and LBP in postmenopausal women. Specifically, a serum vitamin D concentration < 10 ng/mL is a marker of severe LDD and LBP. Smoking, severe vitamin D deficiency, lack of vitamin D supplementation, high body mass index, and osteoporosis are associated with a higher prevalence of moderate-to-severe pain,” the authors wrote in their conclusion.
Does Vitamin D Protect Against Fracture? Data Are Less Clear
A previous study found vitamin D supplements are not effective in preventing fractures or falls and did not significantly impact bone mineral density.
In this study, researchers reviewed 81 trials that included 53,537 participants. Pooled analyses showed no impact on total fracture or falls. Randomized controlled trials measuring high-dose versus low-dose vitamin D and doses >800 IU/day had similar outcomes. Over a five-year period, vitamin D intake had no significant impact on bone mineral density at any site.
Similarly, a study found that while vitamin D on its own may not play a significant role in fracture prevention, it was more effective when paired with calcium. The observational studies meta-analysis included 11 studies with 39,141 total participants, 6,278 fractures and 2,367 hip fractures. For every 10.0 ng/mL-increase in 25-hydroxyvitamin D (25[OH]D) concentration, the adjusted risk ratio (RR) for any fracture was 0.93 (95% confidence interval [CI], 0.89-0.96), while the adjusted RR for hip fracture was 0.80 (95% CI, 0.75-0.86). The meta-analysis of RCTs of vitamin D supplementation alone (daily or intermittent dose of 400-30,000 IU) included 11 trials encompassing 34,243 total participants, 2,843 fractures, and 740 hip fractures. In this analysis, no risk reduction was observed in any fracture (RR=1.06; 95% CI, 0.98-1.14) or hip fracture (RR=1.14; 95% CI, 0.98-1.32), but the authors noted that “these trials were constrained by infrequent intermittent dosing, low daily doses of vitamin D, or an inadequate number of participants.”
A different meta-analysis of RCTs included six trials encompassing 49,282 total participants, 5,449 fractures, and 730 hip fractures. These trials assessed combined vitamin D and calcium supplementation; in this analysis, the authors observed a 6% reduction in risk for any fracture (RR=0.94; 95% CI, 0.89-0.99) and 16% reduction in risk for hip fracture (RR=0.84; 95% CI, 0.72-0.97).