High-dose vitamin D supplementation and bone health

Dr Burt and colleagues concluded that treatment of healthy adults with high-dose vitamin D supplementation for 3 years did not have any beneficial effects on volumetric bone mineral density (BMD) and bone strength.1 Although these results appear similar to recent findings that disputed the effectiveness of vitamin D supplementation in the general population,2 we emphasize that these results should not be generalized. The baseline mean serum 25 hydroxyvitamin D (25[OH]D) concentrations in the 3 groups randomized to different doses of supplementation ranged from 76.7 to 81.3 nmol/L, considerably higher than currently accepted thresholds for diagnosing vitamin D deficiency (≤50 nmol/L) and insufficiency (≤75.0 nmol/L).3 Although participants with serum 25(OH)D concentrations less than 30 nmol/L were excluded from the study, it cannot be concluded that those with serum 25(OH)D values between 30 and 75 nmol/L would have responded more favorably to high-dose vitamin D supplementation in terms of volumetric bone density and bone strength. We believe that a further sub-analysis of these patients might be advisable.