A number of studies have shown that melatonin can reduce mortality from a variety of viral infections. Lab studies using mice and other animals demonstrated that melatonin has a protective effect against encephalomyocarditis virus, Semliki Forest virus, Aleutian disease, murine leukemia retrovirus, and West Nile virus.

Some concerns were raised that melatonin may not be an ideal choice for use against the H5N1 avian flu virus, as there are a few reports that it raises levels of inflammatory cytokines, including interleukin-1beta (IL-1), tumor necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma). In the mice studies, the action of IL-1 appears to be the critical factor; when IL-1 was blocked, melatonin gave no additional protection against viruses, but blocking TNF or IFN did not increase or decrease the effectiveness of melatonin. PMID:14962057 (cache)

While there are some reports that melatonin raises TNF, there are more studies that found that it lowered TNF. A study on mice infected with Venezualan Equine Encephalitis virus found that TNF levels in the brain were decreased, not increased. PMID:12716016 (cache) Incubating immune cells with increasing levels of melatonin led to lower and lower levels of TNF in the immune cells, with a maximum of 98% reduction in TNF. PMID:16179544 (cache) Melatonin and its oxidation product AFMK both reduced the release of TNF in neuterophils and peripheral blood cells; AFMK had a stronger effect than melatonin itself. PMID:15465605 (cache)

Melatonin alone has no effect on the inflammatory RANTES compound, but in combination with TNF, melatonin increases RANTES. It was suggested that the elevation of RANTES could play a role in the worsening of asthma. PMID:15537425 (cache) It has been suggested that the increase in IL-1 levels from melatonin may make a supplement undesirable for those with rheumatoid arthritis.

In a study carried out on humans in 2004, it was found that in the early stages of sleep when melatonin was rising, TNF and other inflammatory Th1 cytokines went up slightly (but less than predicted). Unexpectedly, the later half of the night was associated with the Th2 immune response, and an increase in cytokines that are antagonistic to TNF. PMID:15157951 (cache)


Disclaimer Topics Page Copyright