Saturday, August 1, 2009

Vitamin D Deficits Engender More Pain in Women?

Previous investigations have shown an association of deficient vitamin D levels and chronic musculoskeletal pain syndromes [see reports]. In a recently published report, researchers in the UK [Atherton et al. 2009] examined the association between vitamin D status (measured as 25(OH)D [25-hydroxyvitamin-D]) and chronic widespread pain (CWP) in a nationwide population sample of 45-year-old white adults (n=6,824). CWP, which was consistent with American College of Rheumatology criteria as being a component of fibromyalgia, was present in 11.1% of the men and 12.5% of women.

Overall, women with CWP had mean 25(OH)D concentrations of roughly 19 ng/mL, compared with 21 ng/mL in women without CWP. In men, comparable concentrations were 21 ng/mL and 21.4 ng/mL, respectively. The prevalence of CWP varied by 25(OH)D concentration in women but not in men, and this was not accounted for by differences in lifestyle, social factors, anxiety, depression, or diet. In women with CWP, 41% had 25(OH)D levels less than 30 ng/mL, and the lowest prevalence of CWP, 18%, was in women with 25(OH)D ranging from 30 to 40 or more ng/mL, which is normally an adequate vitamin D concentration. Despite these trends, the authors conclude that their study does not support vitamin D status as a key determinant of CWP; albeit, there is some evidence for an association in women.

Clinical Commentary: This study actually provides little clarification of the association between vitamin D deficiency and pain. Average vitamin D concentrations in all subjects — men and women, with and without CWP — were similar and fell below the usually accepted optimal range of 30 to 50 ng/mL. It is presently unknown why some persons are more adversely affected by deficient vitamin D levels than others. Of interest in this study, nearly 1 in 5 women with CWP had vitamin D concentrations within the optimal range, which suggests that they may have needed vitamin D levels above what is usually considered an “adequate” threshold.

Another interesting outcome was an association of CWP with a body mass index (BMI) curve that was U-shaped; that is, there was a higher CWP prevalence in both underweight and obese subjects, and these two groups also had the lowest 25(OH)D concentrations. These relationships would be worthy of further investigation.

The researchers did not assess parathyroid hormone (PTH) levels, which, if elevated, would have been a diagnostic marker of painful osteomalacia associated with inadequate vitamin D (no matter what level the actual 25[OH]D concentration was at). Finally, it is disappointing that the researchers apparently did not provide vitamin D supplementation for subjects with CWP, at the least those with suboptimal 25(OH)D levels, to observe any pain relief.

Reference: Atherton K, Berry DJ, Parsons T. Vitamin D and chronic widespread pain in a white middle-aged British population: evidence from a cross-sectional population survey. Ann Rheum Dis. 2009;68:817-822.
Also see: Pain Treatment Topics has comprehensive research papers on this topic of vitamin D for chronic pain syndromes [
click here].