The supplements are only available via prescription in the UK
A readily available medication in many countries, melatonin supplements are often assumed to be risk-free given the body’s natural production of melatonin to regulate sleep patterns. However, scientists have recently flagged a significant potential concern.
Researchers from the American Heart Association have revealed findings from their latest study suggesting that prolonged use of melatonin supplements could adversely affect overall health. Specifically, they found that individuals who had taken melatonin for at least 12 months were more likely to be diagnosed with heart failure, require hospital admission for the condition, or die from any cause.
The researchers highlighted the safety concerns raised by these results, while also noting that they couldn’t definitively link the supplements as the direct cause of these cardiac effects. The team called for further research to determine the true safety of melatonin for cardiovascular health.
Ekenedilichukwu Nnadi, M.D., lead author of the study and chief resident in internal medicine at SUNY Downstate/Kings County Primary Care in Brooklyn, New York, said: “Melatonin supplements may not be as harmless as commonly assumed. If our study is confirmed, this could affect how doctors counsel patients about sleep aids. Melatonin supplements are widely thought of as a safe and ‘natural’ option to support better sleep, so it was striking to see such consistent and significant increases in serious health outcomes, even after balancing for many other risk factors.”
The researcher added: “Also, while the association we found raises safety concerns about the widely used supplement, our study cannot prove a direct cause-and-effect relationship. This means more research is needed to test melatonin’s safety for the heart.”
The researchers analysed five years of medical records for adults with chronic insomnia who had been documented as using melatonin for over a year. These individuals were then compared with similar people in the database who also suffered from insomnia but had never been recorded as taking melatonin. Those on alternative sleep medications or with previous heart failure diagnoses were excluded from the study.
The primary analysis showed that adults using melatonin to treat their insomnia for 12 months or longer had approximately 90 per cent greater likelihood of heart failure over five years compared to non-users, reports the Mirror.
People who had at least two melatonin prescriptions filled at least 90 days apart faced an 82 per cent elevated risk of the cardiac condition. A subsequent analysis also found that individuals taking melatonin were nearly 3.5 times more likely to require hospitalisation for heart failure compared to those not taking the supplement.
They were also nearly twice as likely to die from any cause during the five-year period than the non-melatonin group.
In the UK, melatonin is only available on prescription, whereas in countries like America, it’s sold over-the-counter. This posed a limitation for the study as people taking the supplement without a prescription could have been categorised in the non-melatonin group due to it not being recorded on their health record.
The researchers also didn’t have information concerning the severity of insomnia or the existence of other mental health conditions.
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