Melatonin Strengthens Old Bones in the Human Body

Melatonin is a hormone found naturally in the body that is also used as a medicine to alter one's internal clock, primarily for adjusting sleep-wake cycles. Researchers led by Faleh Tamimi of McGill University found another use for melatonin.

In experiments with laboratory rats, the researchers sought to discover if melatonin would regulate the circadian rhythms of elderly rats, which would then reduce the activity of the osteoclasts, thus slowing the process of bone breakdown. Circadian rhythms are physical, mental and behavioral changes that follow a 24-hour cycle and respond to light and darkness in the environment. Osteoclasts are the cells that degrade bone to initiate normal bone remodeling (among other duties).

In the experiments, researchers at the University of Madrid (cooperating members of the study who were housing the rats) administered melatonin supplements that were diluted in water. The rats were 22 months old, which are equivalent to 60-year-old humans. The control group did not receive any melatonin.

Following the ten-week experiment, the researchers removed the rats' femurs to observe their bone density and strength. After a series of tests, they determined the rats that received the melatonin doses witnessed a significant increase in both bone volume and density and it took much more force to break their bones than the rats who were not given melatonin.

Despite these findings, the researchers are not yet ready to say the same for humans, although signs point to that eventually being the case.

"Until there is more research as well as clinical trials to determine how exactly the melatonin is working, we can't recommend that people with osteoporosis go ahead and simply take melatonin supplements," said Tamimi, in this McGill University news release. "I am applying for funding to pursue the research and we hope to have answers soon."

The study, "Melatonin dietary supplement as an anti-aging therapy for age-related bone loss," was published in the journal Rejuvenation Research.