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Light wave therapy - how does it actually work?
What is going on with that light wave therapy? The latest FDA approved LED devices include DPL therapy System for muscle relaxation, temporary relief of minor muscle and joint pain, aches and stiffness (including those caused by arthritis), as well as the NeuroStar TMS (Transcranial Magnetic Stimulation) Therapy system for helping those with standard-treatment-resistant depression.
Is there something that light wave therapy - also known as infrared LED therapy, pulsed infrared light therapy, cold laser or low-level laser therapy - cannot do? Is it for real?
When Endre Mester, back in 1968, pointed his ruby laser onto the laboratory mice, he expected these highly concentrated light waves to destroy, or at least weaken the implanted tumor cells. To his surprise, the light waves had no effect on tumor cells. But they did noticeably speed up healing of skin incisions made during cell implanting.
This unexpected turn of events marks the birth of the light wave therapy.
Nearly four decades and some 2000 studies later, therapeutic use of light waves has evolved into various forms of laser, LED (light-emitting diode) and SLD (super-luminous diode) treatments that stimulate growth, help wound healing, pain relief, and fight inflammation. The effect varies with the type of cell, light frequency/wavelength (the most beneficial being red and infrared light, from 630 to 900nm wavelength), intensity and radiation pattern (continuous vs. pulsed).
In general, the correct influx of light energy produces extended beneficial effect by
elevating the efficiency of cellular metabolism.
The benefit id greatest with cells whose metabolism is, for any of a number of possible reasons -toxic chemical overload, nutritional deficiencies/imbalances, injury, inflammation, various disease states - compromised. There are direct similarities between beneficial effects of light therapy with those produced by QRS treatments, implying that weak, non ionizing electromagnetic energy can significantly influence cellular processes in the wide range of frequencies.
Mono- and combined frequency light therapy is used in regular, sport and veterinary medicine, as well as for cosmetic skin treatments; it is used to stimulate plant growth and enhance their physical and biochemical properties. With NASA-developed LED technology, the therapy has become inexpensive, safer than in already very safe laser-applied mode, more versatile and flexible. According to Dr. Harry Whelan,
it could be beneficial in a wide variety of medical applications,
including treatment of serious burns, crush injuries, non-healing fractures, muscle and bone atrophy, traumatic ischemic wounds, radiation tissue damage, compromised skin grafts, and tissue regeneration.
In the U.S., however, therapeutic use of light wave therapy in medicine is still very limited. Without apparent reason, the Food and Drug Administration is dragging its feet when it comes to allowing its general use for rehabilitation. Since 2002 it only approved about three dozens of light-emitting devices for their intended, rather narrow applications (wrist and hand pain caused by carpal tunnel syndrome - the first FDA approved light therapy application - temporary relief of neck and shoulder pain of musculoskeletal origin, pain caused by iliotibial band syndrome and cosmetic treatments such as for hair loss, acne and wrinkles).
The FDA's reluctance to allow for much wider medicinal use of the light therapy has no factual basis. Extensive experimental data shows that the efficacy of light therapy ranges from significant to spectacular and - unlike prescription drugs, including quite a few of those still on the market - has
no serious side effects, let alone deaths.
One would think that lots of good things can be done with the treatment method capable of restoring vision in blinded rats (Whelan, 2002), or to kill brain tumor without affecting other body tissues. The latter was demonstrated by a clever technic of administering the killing drug - Photophrin II - absorbed mainly by the tumor, and then activating the drug by LED light. It was used successfully on a young girl in the FDA-approved clinical trial by Dr. Whelan and a team of neurosurgeons and neurologists at the Children's Hospital in Milwaukee, WI, 1994.
The light therapy, when applied with LED light, is also inexpensive compared to drugs. So why being more efficient, safer and less expensive than alternative drug treatments is not good enough reason for the FDA to allow its much more widespread use? Dr. C. Enwemeka, professor and dean at the New York Institute of Technology, says that the light wave therapy could
save hospitals and the nation billions of dollars
a year in the treatment of chronic healing-resistant wounds alone.
And that is probably the "problem". Better part of those billions of dollars - and much more - saved to the nation would be sorely missed by the FDA's major customer and revenue source: pharmaceutical industry. It is no news that it deeply infiltrates and influences the FDA.
The agency's formal reason for limiting medical application of light wave therapy is that the specific mechanism of its action is still not fully explained. Noting that the FDA apparently doesn't see it as a problem when it comes to great many prescription drugs, what is it that we know about healing magic of light? How does it do it?
Being a form of electromagnetic energy, light waves penetrate tissues and cells. According to spectroscopic measurement for 630-800nm wavelengths, the depth of penetration into human tissue is up to 23cm (through surface tissue into wrist flexor and calf muscle, Chance et al. 1998).
Within body cells, they are absorbed by various molecular structures - so called photoacceptors - mainly enzymes and other regulatory proteins involved in the process of cellular respiration, growth and proliferation. Within certain range of intensity, absorbed energy stimulates the activity of these components of the cellular respiratory chain,
enhancing the efficacy of energy production within the cell.
This, in turn, makes the cell more viable in every aspect of its functioning.
Optimum dose of irradiation with light varies with the tissue type; in general, it ranges between 1 and 6 J/cm2 (joule per square cm). Application of combined selected wavelengths are generally more effective than a single wavelength. According to Dr. Whelan (The NASA Light-Emitting Diode Medical Program, 2000), optimum LED wavelengths include 680, 730 and 880nm; a single such application at 4 J/cm2 had quintupled DNA synthesis in muscle cells and fibroblasts (connective tissue cells) of laboratory animals.
If light intensity is much weaker than the optimum level, its positive, stimulating effect vanishes. If it is much stronger, it can damage (inhibitory effect), or even destroy cellular photoacceptors. At high intensities its effect is similar to that of ionizing radiation, capable of breaking molecular bonds and/or producing excessive levels of reactive oxygen species (ROS).
However, the intensity gap between insufficient and damaging level of irradiation is very wide. For instance, stimulating dose of blue light on E. coli bacteria is between 0.001 and 0.1 J/cm2, while lethal effect requires intensity between 102 and 104 J/cm2.
The difficulty of determining the specifics of mechanism by which light energy benefits cellular function results from the need not only to identify specific cellular photoacceptors, but also to track down the entire cascade of reactions triggered by their energy-enhanced state. The four so called "primary reactions" inside a cell irradiated by light are considered to be:
acceleration of electron transfer due to enhanced activity of the excited cytochrome c oxidase enzyme molecule, resulting in more efficient energy production
increased ROS production (either singlet oxygen or superoxide anion) by molecules like NADH oxidase enzyme, triggering cascade of reactions resulting in intracellular changes - increase in proton gradient and electrical potential of mitochondrial membrane, increase in ATP (adenosine triphosphate) concentration, increase in cellular redox (oxidation) potential, increase in hydrogen ion [H+] concentration (decrease in cellular pH), decrease in cellular membrane electrical potential, activation of ATPase enzymes (proteins forming membranal ion channels), increase in potassium [K+] and decrease in sodium [Na+] ions concentration, altered flow of calcium ions between mitochondria and cytoplasm, production of cyclic nucleotides (particularly cyclic 3',5'-adenosine monophosphate, or cAMP) - that can increase nucleic acids (RNA/DNA) synthesis rate
partial reversal of the inhibition of cellular (mitochondrial) respiration by cytochrome c oxidase inhibiting nitric oxide (NO), and
local transient heating of chromophores (a group of atoms in a molecule selectively absorbing light)
Each of these primary reactions triggers a cascade of secondary reactions (one such possible cascade is roughly outlined for the increased ROS production (Molecular Mechanism of the Therapeutic Effect of Low-Intensity Laser Radiation, T.I. Karu, 1988).
The last hypothesis is probably relevant only to some laser light applications. Having much longer coherence length than LED light, it forms more pronounced random interference spots (speckles) with higher concentration of the energy. At the standard treatment intensity levels with LED light, there is no appreciable thermal effect.
For each of the three other mechanisms there is supporting evidence, with the first one - acceleration of electron transfer enhancing cellular energy production - being considered by most as the dominant primary effect in standard therapies (it is possible that with different light intensities and/or modes of therapy, the other two mechanisms could become dominant).
Other hypotheses do exist. One of them, attempting to explain therapeutic effect of infrared light therapy on diabetic peripheral neuropathy, speculated that it is caused by light waves elevating NO blood level. According to it, NO's vasodilating action would increase blood supply to the nerve cells, improving their function. However, a recent small study (Arnall et al. Dec. 2008) has found that treatment with infrared light was, in fact, followed by significantly lower NO blood concentration. Thus, it concluded that infrared light improves peripheral sensation in patients by a mechanism other than an increased NO production.
Interesting - and not surprising - is that affecting cellular respiration resulting from its elevated oxidative state (increased ROS production) has recently been found to be the likely mechanism of altering cellular transcription (replicating of DNA segments into RNA) and other processes, as a result of cell-phone type irradiation (Friedman et al. 2007). The fact that weak electromagnetic fields can have significant biological effect in the wide range of frequencies becomes very much evident. And, as any other factor capable of altering biological functions,
it can be both, beneficial or harmful to your health.
A good example are the healing benefits of pulsed low-frequency electromagnetic field therapy vs. evidently dangerous to health continuous random exposure to power-frequency field. Within practically identical frequency and field strength range, the only difference being in the form of a wave (pulsed vs. continuous, respectively), their effect on cellular function - and overall health - is exactly the opposite.
This underlines the importance of proper application of electromagnetic field therapy. Extensive research and decades-long practical worldwide applications of the light wave therapy in various forms show that it has remarkable efficacy and safety, significantly better than prescription drugs or surgery, in general. Sadly, what at present determines the "proper treatment" in the U.S. is - more than anything else - its profit potential for the mighty pharmaceutical industry. R
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