Vitamin D status in anorexia nervosa: A meta-analysis

Objective In anorexia nervosa (AN), osteoporosis and osteopenia are common, which have been associated with low circulating levels of vitamin D (VitD) in other settings. We aimed to meta-analyze cross-sectional studies reporting on VitD parameters in patients with AN and healthy controls (HCs). Method Electronic PubMed search from database inception until December 31, 2013 and meta-analysis of cross-sectional studies comparing serum levels of 25-hydroxyvitamin D (25OH-D), 1,25-dihydroxyvitamin D (1,25OH-D) and dietary VitD between patients with AN and HCs, before or after VitD supplementation. We calculated random effects standardized mean differences (SMDs) ±95% confidence intervals (CIs) as effect size measures. Results Out of 1,739 initial hits, 15 studies with a total of 927 participants (AN-=-408 and HCs-=-519) were meta-analyzed. In the unsupplemented state, both serum 25OH-D (studies-=-4; n-=-168; SMD-=-0.43; 95%CI: -0.83 to -0.03; p-=-.03) and 1,25OH-D levels (studies-=-4; n-=-113; SMD-=-1.06; 95%CI: -1.47 to -0.66; p-<-.00001) were significantly lower in AN than HCs. In AN patients treated with cholecalciferol supplementation, serum 25OH-D levels were significantly higher than in HCs (studies-=-5; n-=-449; SMD-=-0.66; 95%CI: 0.01-1.31; p-=-.05). Paradoxically, despite lower 25OH-D and 1,25OH-D levels, AN patients reported similar intake of VitD compared to HCs (studies-=-6; n-=-314; SMD-=-0.33; 95%CI: -0.16, 0.81; p-=-.19). Discussion Although AN patients reported similar dietary VitD intake compared to HCs, AN patients had significantly lower 25OH-D and 1,25OH-D levels without supplementation. Conversely, supplementation with cholecalciferol fully normalized VitD serum levels. Future studies are needed to clarify the role of VitD supplementation in AN for improving bone health. © 2014 Wiley Periodicals, Inc.