This pigment-producing molecule displays almost unfathomable properties in other species
Could the melanin found in our bodies and in foods like mushrooms help mitigate the increasing amounts of radiation we are exposed to daily?
Over the past decade, one of the most interesting concepts I have come across while browsing the biomedical literature is the possibility that the biological role of melanin in the human body may extend far beyond the simple protection against UV rays.
In fact, a recent and highly controversial paper proposes that melanin is responsible for the production of the majority of the body’s energy, effectively challenging the view of cellular bioenergetics centered on ATP and glucose that has dominated the biology over the past half century.
Research is now emerging indicating that melanin may function in a manner analogous to energy harvesting pigments such as chlorophyll. While the proposed ability of melanin to convert sunlight into metabolic energy has startling implications (one of which is the taxonomic reclassification of our species from heterotrophic to photoheterotrophic), what may have even more dramatic implications is the prospect that melanin can actually both protect us against ionizing radiation and turn some of it into metabolically useful energy.
Radioisotopes are increasingly accumulating in the environment, the food chain and our bodies, due to nuclear weapons testing, routine releases from the nuclear industry, hydraulic fracturing, electrical industries coal and, more recently, global fallout from the Chernobyl and Fukushima meltdowns. Add to that the inevitable onslaught of radiation exposures from medical use, cellphone communications and WiFi technology, and air travel, and you can virtually guarantee that your body burden of radiation exposure is significant and poses a health risk.
For these reasons, reducing radiotoxicity and/or improving detoxification mechanisms should be a universal concern.
The mysterious properties of melanin
Melanin is, indeed, one of the most interesting biomolecules yet identified. The first known organic semiconductor, it is capable of absorbing a wide range of the electromagnetic spectrum (which is why it appears black), including converting and dissipating potentially harmful ultraviolet radiation into heat. It performs a wide range of physiological roles, including scavenging of free radicals, chelation of toxic substances, protection of DNA, to name a few. It is also believed to have been one of the essential ingredients for life on this planet. Beyond its potential to convert sunlight into metabolic energy, it can also convert ionizing gamma radiation into useful energy. Outside of the realm of comic book heroes, who would have ever thought such a thing was possible?
The first time I found this possibility in the scientific literature was a 2001 Russian report of the discovery of a species of melanin-rich fungus colonizing and apparently thriving in the walls of the still-hot fusion reactor site. of Chernobyl. In 2004, the same observation was made for the surrounding soils of the Chernobyl site. We also know that, based on a 2008 report, pyomelanin-producing bacteria were found in thriving colonies in uranium-contaminated soil. There’s also a 1961 study that found, surprisingly, melanin-rich fungi from the soils of a Nevada nuclear test site survived radiation exposure doses of up to 6400 Grays (about 2000 times a lethal dose for humans). Clearly, something about melanin in these species not only enables them to survive radiation exposures that are normally lethal to most life forms, but actually attracts them to them. Could fungi actually use melanin to “feast” on the free lunch of anthropogenic radioactivity?
Remarkably, in 2007, a study published in PLoS titled “Ionizing Radiation Alters Electronic Properties of Melanin and Enhances Growth of Melanized Fungi,” found that fungal cells exhibited increased growth compared to non-melanized cells after exposure to ionizing radiation. In other words, the mushrooms grew better after being exposed to radiation. Irradiated melanin from these fungi also altered its electronic properties, which the authors say raised “intriguing questions about the potential role of melanin in energy capture and utilization.”
To learn more about this groundbreaking study, see a 2007 report in the MIT Technology Review titled, Eating Radiation: A New Form of Energy?
Can melanin give us superpowers?
The question arises, could consuming melanin from mushrooms protect people higher up the food chain (like humans) from radiation exposure?
This question appears to have been answered in the affirmative by a 2012 study published in the journal Toxicology and Applied Pharmacology, titled “Melanin, a promised radioprotector: Mechanisms of actions in a mice model,” which found that when melanin isolated from Gliocephalotrichum simplex fungus was administered at a dose of 50 mg/kg body weight to BALB/c mice before exposure to 6-7 Grays of gamma radiation, it increased their 30-day survival by 100%. The study also noted that melanin up to a dose of 100 mg/kg (ip) did not cause adverse health effects in mice.
In the conclusion of the study, the authors stated, “The observed attenuating effects of melanin in the present study are gaining importance, particularly in nuclear emergencies, but need to be validated in humans by more detailed experiments. Prior to these confirmations and based on ongoing investigations, it can be concluded that during such emergencies, melanin-rich diets may be beneficial in overcoming radiation toxicity in humans.
Another study published in 2012 in Cancer Biotherapy & Radiopharmaceuticals entitled “Compton Scattering by Internal Shields Based on Melanin-Containing Mushrooms Provides Protection of Gastrointestinal Tract from Ionizing Radiation”, confirmed that the remarkable radioprotective properties of melanized mushrooms were in fact specific to the melanin and due to other well-known therapeutic compounds in fungi.
As succinctly summarized on the Small Things Considered website: “The authors fed mice a fungus used in East Asian cuisine called Judas’ ear, tree, or jelly ear (Auricularia auricula-judae) a hour before giving them a powerful dose of 9 Gy with the beta emitter Cesium137. For perspective, anything over ~0.1 Gy is considered a dangerously high dose for humans. All control mice died within 13 days while about 90% of those fed mushrooms survived. Mice fed white mushroom (ceps) died almost as quickly as controls, but those fed white mushrooms supplemented with melanin also survived.
So how does melanin perform this trick?
A clue was provided by a 2011 study published in Bioelectrochemistry titled “Gamma radiation interacts with melanin to alter its redox potential and results in production of electric current”, where ionizing radiation was found to alter the redox potential of melanin.
Unlike most other biomolecules, which experience a destructive form of oxidative damage as a result of radiation exposure, melanin remained structurally and functionally intact, appearing capable of producing direct electrical current. This current, theoretically, could be used to produce chemical/metabolic energy in living systems. This would explain the increased growth rate, even under low nutrient conditions, in certain types of gamma-irradiated fungi.
So, you might be wondering, what is a good source of supplemental melanin for those interested in its radioprotective and radiotrophic (“radiation absorption”) properties? I believe the chaga (Inonotus obliquus) is one of the most promising candidates. Not only is it one of the nutritionally dense mushrooms, containing an immense amount of melanin, but it was known by the Siberians as the “gift of God” and the “mushroom of immortality”, by the Japanese as “the diamond of the forest”. and by the Chinese as the “King of Plants”. There is also an increasingly compelling body of scientific information demonstrating its health benefits in conditions as serious as cancer.
It should be noted that there is a profound toxicological difference between the type of radiation exposure that comes from the outside in, for example being irradiated at a distance by radioactive material outside of us, and from the inside outwards, for example the absorption of low-dose radioisotopes. The latter can be orders of magnitude more dangerous, as radioisotopes like uranium-238, cesium-137 and plutonium-239 can be absorbed into tissues and remain there for a lifetime, wreaking havoc with each instant.
Due to a phenomenon known as the photoelectric effect, low-dose radionuclides like uranium-238, which are technically weak emitters of alpha radiation, can be tens of thousands of times more damaging to our DNA than current radiological risk assessment models do not provide for this.
We mention this in order to properly qualify the above information, as it could be very misleading to those who interpret it to mean that one can simply supplement with an edible melanin product to reduce and even benefit from radiation exposure. Nothing can effectively reduce the radiotoxicity of incorporated radionuclides beyond their elimination from the body.
That said, apple pectin was used successfully after Chernobyl to significantly reduce the body burden of absorbed radionuclides in thousands of Russian children. Moreover, once we grasp the genocidal implications of the widespread contamination of the biosphere with the routine and accidental releases of radiotoxics that maintain their toxicity for thousands, and in some cases, millions of years (e.g., plutonium -239 has a half-life of 24,100 years and Uranium-238 has a half-life of 4.4 billion years), we realize that the solution (if there is one) is to eliminate gradually and trying to mitigate the global fallout from the activities of the nuclear industry over the 75 years.