Melatonin and Cancer

Melatonin and Cancer

Spring 2016, Living Well Magazine

Melatonin has a twofold importance for cancer, in that it has both a direct influence on the course of cancer, and is also is affected by the same risk factors that exist for cancer.

Melatonin is a hormone produced by the pineal gland, and is responsible for regulating our body clock, also known as ‘circadian rhythms’. Melatonin production levels vary according to the time of day, with the highest concentrations being at night. Sleep patterns are immediately influential on melatonin levels. Sleep disruption is also directly linked to cancer risk.

Melatonin has been shown to improve survival and performance status in patients with advanced cancer, and is a powerful antioxidant and immunomodulator with anti-tumour, anti-cytokine, anti-insomnia and anti-body mass loss effects. It also reduces radiation and chemotherapeutic induced toxicity, making it an indispensable part of a cancer treatment protocol.

While high levels of melatonin supplementation need careful monitoring by a qualified health professional, naturally enhancing the body’s production of melatonin is relatively easy.

Meditation practices can support melatonin production, as can prudent sunlight exposure and subdued lighting after sunset. Calorie restriction and exercise is also supportive of melatonin production. From a dietary perspective many foods rich in calcium, magnesium, B6, and niacinamide are also useful, as are tryptophan-rich foods as found in many seeds, nuts and soy products.

It is advisable to also avoid the things that inhibit melatonin production where possible, such as caffeine, beta +/- alpha blockers, sedatives, alcohol and tobacco. Night shift workers can be particularly susceptible to reduced melatonin. Jetlag can also have an effect.  Electro-magnetic radiation, which causes oxidative stress, will also inhibit melatonin production. Just as calorie restriction and exercise can support melatonin production, excessive calories and inactivity can have the opposite effect.

Correlation between the onset of tumours and alterations in blood melatonin levels have been investigated and in ten trials on tumours, melatonin reduced the risk of death at one year, without any adverse effects. This result was achieved consistently across different doses and for different types of cancers. Although the mechanism by which this occurs is still under investigation, it is considered that melatonin inhibits the release and activity of growth factors associated with tumours and down regulates the gene expression. Melatonin provides an exciting, accessible and cost-effective treatment with significant potential.

Melatonin is proven to reduce cancer risk and enhance quality of life by diminishing cancer-induced body clock disruption. As research has shown the substantial reduction in risk of death, low adverse events reported, and low costs related to this intervention suggest great potential for melatonin in treating cancer and many other chronic diseases.


Biological effects of melatonin: Am J Hospice & Palliative Care. 2005;22(4):295-309.

Melatonin reduced the risk of death: Mills E, Wu P, Seely D, Guyatt G. Melatonin in the treatment of cancer: a systematic review of randomized controlled trials and meta-analysis. J Pineal Res. 2005;39(4):360-6.

Things that affect melatonin (e.g. nurses on shift-work) may also be risk factors for cancer (e.g. breast) Franzese E, Nigri G. Night work as a possible risk factor for breast cancer in nurses. Correlation between the onset of tumours and alterations in blood melatonin levels. Prof Inferm. 2007;60(2):89-93.

General: Reiter R. in ‘Melatonin’, Bantam Books -1995