I have become a big fan of LED light therapy with monthly salon sessions and top ups at home with my Baby Quasar ($402 in the TIA shop). My husband is more than a little bemused by these rituals and a few months ago, he asked my how LED works to rejuvenate the skin. It's a good question and, until recently, it was poorly understood. Scientists could see the results, but couldn't explain them. Apologies for the long post, but it turns out that LED is complex and controversial.

Granted that even NASA said good things about LED: “Low-energy photon irradiation by light in the far-red to near-IR spectral range with low-energy (LLLT) lasers or LED arrays has been found to modulate various biological processes in cell culture and animal models. This phenomenon of photobiomodulation has been applied clinically in the treatment of soft tissue injuries and the acceleration of wound healing."

But even NASA was a bit vague about the whys and hows. Around 2003, it was being described as similar to photosynthesis. A Harvard paper summed it up in 2006: "The use of low levels of visible or near infrared light for reducing pain, inflammation and edema, promoting healin of wounds, deeper tissues and nerves, and preventing tissue damage has been known for almost forty years since the invention of lasers. Originally thought to be a peculiar property of laser light (soft or cold lasers), the subject has now broadened to include photobiomodulation and photobiostimulation using non-coherent light. Despite many reports of positive findings from experiments conducted in vitro, in animal models and in randomized controlled clinical trials, LLLT remains controversial."

The controversy was due to the mechanism of how LED or low level light therapy (LLL) works being a bit of mystery. Although researchers, such as these in Denmark, established that it does boost collagen. The second issue - contributing to the mystery - is that experiments would vary things like wavelength, pulse density and goodness knows what making it difficult to see replicated conclusions.

Then came along some research that suggests that it has to do with water. Researchers in Germany concluded that "by targeting water layers on elastin, facial wrinkle levels could be significantly reduced by irradiation of the skin with visible light, which was found to interact with interfacial water layers on model substrates."

So there we have it. But not so fast. I was pulling all this information together when, the other day, I received an email from Angela with a link to an article that said that researchers found that LED did a good job on wrinkles but also the exposure to intense LED light generated high levels of reactive oxygen species, as byproducts that can potentially damage cells. Eeek!

To combat that effect, the article went on to say the researchers combined the LED with a potent antioxidant in green tea extract called epigallocatechin gallate. And all was well again. Hmm. What was going on? And, as Angela, reasonably asked, would our Baby Quasar's be destroying our cells?

The researchers turned out to be none other than the Germans who came up with the water theory mentioned above. I went back to look at their research paper and couldn't find a single mention of reactive oxygen species being generated or epigallocatechin gallate. Nor could I find any other research papers of theirs that did - only the article (which didn't have any links back to the research). Perhaps the article was planted by the green tea council.

Most of the science seems to agree that light therapy increases production of ATP (the energy engine of cells) and the modulation of reactive oxygen species and that, according to that Harvard paper mentioned above, "these effects in turn lead to increased cell proliferation and migration (particularly by fibroblasts), modulation in levels of cytokines, growth factors and inflammatory mediators, and increased tissue oxygenation."

Then I found some research that focused specifically "on the role of reactive oxygen species in the cellular and tissue effects of low level light therapy (LLLT)." It said that ROS scavengers, antioxidants and ROS quenchers block many LLLT processes. However, it concluded that  "it may be the case that LLLT can be pro-oxidant in the short-term, but anti-oxidant in the long-term."

This chimes with a Chinese study that suggests there may be something to the green tea theory. It says that ROS can be activated by LED but this is significantly diminished by applying vitamin C or superoxide dismutase.

My take on all of this is that the benefits of LED are well-documented and wide-ranging. However, the light can also signal scavengers in the short-term, but that these are ultimately overthrown by the antioxidant activity that the light stimulates. On the other hand, using a topical antioxidant seems to speed up that process. So I am definitely going to continue enjoying the benefits of my Baby Q, but will be sure to slather on my favorite serum first.