Endocrine Abstracts

Introduction: Melatonin is involved in many physiological processes, including the regulation of circadian rhythms, sleep, antioxidant effect, aging, tumor growth, reproduction and bone formation. The latter function is also regulated by the metabolism of vitamin D. Our goal during this study is to detect a possible increase in vitamin D levels under the effect of exogenous melatonin.

Participants and methods: Different anthropometric parameters were collected (weight, height, body mass index, percentage of fat). The experimental protocol is carried out in a randomized clinical trial between an overnight intake (around 9 p.m.) of melatonin and double-blind placebo, once in the middle of the follicular phase and once in the middle of the luteal phase. The dose is determined at around 9 a.m. the next day, using an immuno-electro-chemiluminescence method on the Cobas 6000 analyser from Roche.

Results: Ten healthy young women between the ages of 20 and 23 were included in our study after obtaining their consent. The mean age of the participants was 21.63 ± 0.94 years. The average height of our patients was 165.72 ± 3.38 m. the average weight of our patients was 59.45 ± 3.5 kg. Vitamin D levels were significantly higher after taking melatonin (mean 13.6 ± 7.9 ng/ml) than after taking placebo (mean 12.68 ± 5.7 ng/ml) during the follicular phase (P=0.001). Whereas, the increase in vitamin D with the intake of melatonin (mean of 15.8 ± 7.8 ng/ml) compared to the taking of placebo (mean of 14.6 ± 5.7 ng/ml) was not significant during the luteal phase (P=0.7). In addition, there was no significant variation in vitamin D levels between the luteal phase and the follicular phase when taking placebo (P= 0.07) and when taking melatonin (P= 0.25).

Conclusion: Melatonin can regulate the metabolism of vitamin D. indeed the vitamin D receptor can act as a nuclear receptor for melatonin. Further studies are essential to better explain the relationship between melatonin and vitamin D according to menstrual cycles.