Research Roundup 12 - Melatonin and Cancer
Melatonin is a hormone. It is secreted by a small structure in the brain, called the pineal gland. One of its main functions is to maintain the body’s normal 24-hour rhythm, known as the circadian rhythm. Production of melatonin is related to light. When it is light, less melatonin is produced. When it is dark, more melatonin is produced. Too much artificial light at night causes a decrease in melatonin in the body. So does too little light during the day. Jet lag can also affect melatonin levels, until the body adjusts to the new light cycles. Increasing melatonin at night helps people and animals sleep. When the melatonin cycle or level is disrupted, sleep disturbances can occur.
Many organs have an internal circadian rhythm which is affected by light/dark cycles and by melatonin levels. Interference with light/dark cycles, especially from artificial light at night, has been linked with prostate cancer, breast cancer, and skin cancer. In humans, up to 79% of the differences in number of cases of prostate cancer have been linked to differences in the amount of artificial light seen at night. In the skin, when the rhythm is interfered with, it is less able to deal with stresses on skin cells (from things like sunburn or internal inflammation). This made it more difficult to repair DNA. Abnormal DNA can change any cell into a cancer cell. Occurrence of breast cancer is also higher when there is increased artificial light at night, or decreased melatonin.
Proper use of melatonin has been shown to help with some cancer treatments. (Proper use usually means giving melatonin once a day, in the evening, at doses that are not too high. For people, the proper dose is about 300 mg or less, once a day. For animals it would be proportionately less. Some studies have used it throughout the day also, along with conventional chemotherapy, but there have not been comparisons of those studies with night-only administration of melatonin. ) It has shown promise for non-small cell lung cancer in humans, and for glioblastoma (a type of brain tumor).
Interleukin-2 is a natural substance which helps boost the actions of the immune system. This helps in the treatment of some types of cancer. When it is given with melatonin, there is a bigger effect on tumors and a better survival rate. Doxorubicin is a chemotherapy drug which can work better when melatonin is added as part of the treatment. The effects of Tamoxifen in breast cancer are increased when used with melatonin.
Melatonin can also help decrease side effects of some types of chemotherapy. It protects mice ovaries against the bad effects of Cisplatin, and protects white blood cells against the toxic effects of gossypol.
NSAIDs, beta blockers, and benzodiazapenes are drugs which lower the level of melatonin in the body. If you pet is taking any of these drugs, melatonin supplementation could be helpful. Melatonin given with NSAIDs can help improve their painkilling effect.
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