Saturday, April 30, 2011
Research
MELATONIN: A POTENTIAL PROTECTOR FROM DNA DAMAGE CAUSED BY EXPOSURE TO IONIZING RADIATION
The Japanese people are facing a radiation exposure crisis that has drawn the world’s attention toward the health dangers of both acute and chronic radiation events. A general, safe, effective, readily available and low cost method of reducing tissue damage from exposure to radiation especially over a long period of time is highly desirable.
People can be exposed to radiation in various ways; externally via radiation generated from an external source or internally from ingesting or inhaling radioactive compounds. Some radioisotopes can be flushed from the body but many incorporate into the body’s tissue. (The latter cause prolonged exposure to ionizing radiation.) Damage can be acute where body tissues are killed or chronic where accurate DNA replication and therefore the production of new healthy cells are affected.
Some treatments used post-Chernobyl were ingestion of potassium iodide to protect the thyroid from radioactive iodine accumulation; chelation therapy to remove heavy metal radioisotopes from the body; sodium bicarbonate to treat uranium poisoning; and the use of the dye Prussian blue to help with radioactive Cesium-137 and thallium poisoning. However, all of the above treatments are specific for individual elemental radioisotopes rather than generally protecting against the variety of radioactive elements produced in a nuclear event (1)
Melatonin potentially meets these criteria. Many animal studies and human cell studies indicate that pretreatment with supplemental melatonin can reduce radiation damage up to 30% from an external exposure (2-13). Damage was measured as unrepaired breaks in DNA and the subsequent formation of micronuclei which result from the incorrect copying of DNA during the formation of new cells.
In this article Dr. Reiter states, “Its (melatonin’s) function in reducing damage from ionizing radiation in both animals and humans is well documented [6-13,15] and its protective actions exceed those of other commonly used radioprotectors. Melatonin has been shown to prevent the death of animals given what would normally be a lethal dose of ionizing radiation [5].” One of the referenced studies refers to a human in vivostudy where a single oral 30mg dose of melatonin was administered followed up to 2 hours later by the drawing of blood samples and consequent irradiation. The cultured blood samples showed a significant decrease in leukocyte damage between one and two hours after taking the melatonin (6).
Although human dosage is not established, the implication is that melatonin supplementation could be a general protector from on-going DNA damage caused by ingested or inhaled radioisotopes. One rat study successfully used a series of five injections of 15mg melatonin/kg body weight (14). Another used five injections of 2.5mg/kg pretreatment (15). As the efficacy of melatonin in humans is characterized, effective dosage should be established.
Abstracted by Susan Sweeny Johnson, PhD, Biochem., from a summary of the article, The disaster in Japan: utility of melatonin in providing protection against ionizing radiation. Reiter RJ, Tan DX, Korkmaz A, Manchester LC. J Pineal Res. 2011 Mar 21. doi: 10.1111/j.1600-079X.2011.00881.x.
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