25-Hydroxyvitamin D concentration, vitamin D intake and joint symptoms in postmenopausal women

Introduction: Low 25-hydroxyvitamin D (25(OH) D) concentrations have been associated with radiologic worsening of osteoarthritis in some reports. However, the results are mixed and few studies have evaluated associations between 25(OH) D concentrations and both total vitamin D intake and clinical joint symptoms. Study design: Cross-sectional analyses of information from a subset of 1993 postmenopausal women obtained at baseline entry in the Women's Health Initiative Calcium plus Vitamin D clinical trial. Main Outcome Measures: 25(OH) D concentration, total vitamin D intake (diet plus supplements), presence and severity of joint pain and joint swelling. Results: The 25(OH) D levels were commonly low with 53% having deficient (<50 nmol/L) and only 17% having sufficient (>72 nmol/L) levels. Joint pain (reported by 74%) and joint swelling (reported by 34%) were also commonly reported. 25(OH) D concentrations were modestly correlated with total vitamin D intake (R = 0.29, p < 0.0001); however, considerable variability in 25(OH) D concentrations for a given vitamin D intake was seen. In adjusted linear regression models, lower serum 25(OH) D concentrations were associated with higher average joint pain score (P = 0.01 for trend) with differences most apparent in the lowest 25(OH) D levels sextile. Conclusions: Relatively low 25(OH) D levels and a high frequency of joint symptoms were common in this population of postmenopausal women. Total vitamin D intake was only modestly associated with 25(OH) D. Low serum 25(OH) D concentrations were associated with higher joint pain scores. These findings can inform the design of future intervention trials.