Monday, 28 March 2016

This Substance in Edible Fungi May Have Surprising Benefits

Surprise! Research has found that some edible fungi may have significant protective effects against radiation, specifically those that contain melanin, yes, the same pigment responsible for skin colour in humans. In a time when radiation exposure from a number of sources, including air travel, nuclear power and former testing grounds seems unavoidable, and we're constantly being told that North Korea/Fukushima/something will destroy us all, news of any radioprotective substance is good news.
An early report of this possibility came from Russia in 2001, on the discovery of a melanin-rich species of fungi seeming to thrive within the walls of the Chernobyl meltdown reactor site. Three years later, the same observation was made for the surrounding soils. In 1961, another study found that melanin-rich fungi were growing in a Nevada nuclear test site, surviving doses of up to 6,400 Grays (Gy)! That is around 2,000 times the lethal dose for humans. Amazingly, a study published in PLoS from 2007 revealed that melanised fungal cells showed increased growth relative to non-melanised cells after ionising radiation exposure. The electronic properties of the melanin also changed, raising questions about a role for melanin in energy use.

Close-up image of jelly ear mushroom, a rich source of melanin which has shown radioprotective effects.
Jelly-ear mushroom. Source: Stu's Images
If melanin could protect fungi from radiation, could consumption of mushrooms containing it protect humans and animals? Research published in 2012 found that melanin isolated from the fungus Gliocephalotrichum simplex and administered at a dose of 50mg/kg of body weight increased the 30-day survival of mice by 100%! Melanin up to a dose of 100mg/kg had no adverse effects. Additionally, a second 2012 study on another species of fungus, Auricularia auricula-judae (Jelly ear), suggests that these Radioprotective abilities may be mostly melanin-specific. This time, mice were fed jelly ear, a part of East Asian cuisine, an hour before receiving a 9 Gy dose of radiation from Cesium-137. In comparison, anything over 0.1 Gy is dangerous for humans. All control mice died within 13 days, but 80-90% of the mice that ate jelly ear survived. Those fed white porcini mushrooms died nearly as fast as the controls, but had similar survival rates to the mice fed jelly ear if the white mushrooms were supplemented with melanin.

How does melanin work? In one study, ionising radiation was found to alter the oxidation-reduction potential of melanin, not causing destruction, but instead keeping the melanin intact. The only difference was that melanin was then able to produce a continuous electric current, which may produce energy in living cells. This could explain the increased growth of some gamma irradiated fungi, even in low nutrient conditions. However, this does not mean that it is safe to have radioactive material inside the body. Apple pectin is one substance that can aid in removing radionuclides, with one study showing an over 62% reduction in radionuclides in treated children from the Chernobyl area. Another showed a 28-39% reduction after just 16 days, improving cardiovascular health in the children. However, if used alongside each other, both melanised mushrooms, such as Chaga mushrooms, and apple pectin, and possibly other radioprotective natural medicines, may be a highly effective treatment for radiation poisoning.

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