Melatonin and Aspirin - two common, cheap drugs that together prevent cancer and protect the cardiovascular system

Melatonin, the new partner to aspirin?

Aspirin is the most common drug taken for cardioprotection, with the added benefit of anticancer properties. Yet, it causes gastric haemorrhage. An alternative, safer cardioprotective drug than aspirin is needed.

Melatonin, commonly taken to induce sleep or counter jet lag, has cerebroprotective and anticancer properties, with no reported side-effects. We hypothesise that melatonin has beneficial preventive properties for various organ diseases through mechanisms not shared by aspirin.

Melatonin is synthesised mainly in the pineal gland. Its secretion into the bloodstream is regulated by the environmental light–dark cycle via the suprachiasmatic nucleus. The initial event is that very sensitive ocular photoreceptors stimulate formation of melanopsin within the basal retinal ganglia, which, in turn, sends signals to the pineal gland, from which release of melatonin, synthesised from serotonin, is either stimulated or inhibited.

Melatonin acts by both inducing sleep and restoring the inherent sleep rhythm that is related to the rise and fall of blood melatonin concentrations. Melatonin treatment helps to restore these human circadian rhythms, resulting in better cognition and less daytime fatigue¹. Experimental and clinical data have implicated melatonin in reduction of ischaemic-reperfusion injury, as originally studied in isolated rodent hearts². If melatonin concentrations also affect the occurrence of human infarcts, then the day–night pattern of changes in melatonin blood concentrations² becomes relevant. In patients with ST-elevation myocardial infarction, the normal pattern is reversed, with less melatonin produced at night³.

In the brain, melatonin inhibits the potentially lethal opening of the mitochondrial permeability transition pore in isolated brain mitochondria, albeit at high concentrations⁴.

Finally, melatonin has antidiabetic⁵ and not well studied anticancer properties.

Overall, the organ and vascular protective qualities of melatonin at the cost of very few or no side-effects far exceed those of aspirin, which is much more widely used for cardioprotection than melatonin is. We declare no competing interests.

Lionel Opie, Sandrine Lecour lionel.opie@uct.ac.za Hatter Institute for Cardiovascular Research, Cape Town, Western Cape, ZA 7925, South Africa 

The Lancet, volume 385, February 28, 2015

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