one-year treatment with melatonin increased bone mineral density at femoral neck in a dose-dependent manner, while high dose melatonin increased vBMD in the spine. - GreenMedInfo Summary

Melatonin is known for its regulation of circadian rhythm. Recently, studies have shown that melatonin may have a positive effect on the skeleton. By increasing age, the melatonin levels decrease, which may lead to a further imbalanced bone remodeling. We aimed to investigate whether treatment with melatonin could improve bone mass and integrity in humans. In a double-blind RCT, we randomized 81 post-menopausal osteopenic women to one-year daily treatment with melatonin 1mg (N=20), or 3mg (N=20), or placebo (N=41). At baseline and after one-year treatment, we measured BMD by DXA, quantitative computed tomography (QCT), and high resolution peripheral QCT (HR-pQCT), and determined calcitropic hormones and bone markers. Mean age of the study subjects was 63 (range 56-73) years. Compared to placebo, femoral neck BMD increased by 1.4% in response to melatonin (p<0.05) in a dose-dependent manner (p<0.01), as BMD increased by 0.5% in the 1mg/d group (p=0.55) and by 2.3% (p<0.01) in the 3mg/d group. In the melatonin group, trabecular thickness in tibia increased by 2.2% (p=0.04), and vBMD in the spine by 3.6% (p=0.04) in the 3mg/d. Treatment did not significantly affect BMD at other sites or levels of bone turnover markers, however, 24h urinary calcium was decreased in response to melatonin by 12.2% (p=0.02). In conclusion, one-year treatment with melatonin increased BMD at femoral neck in a dose-dependent manner, while high dose melatonin increased vBMD in the spine. Further studies are needed to assess the mechanisms of action and whether the positive effect of night-time melatonin will protect against fractures. This article is protected by copyright. All rights reserved.