Photobiomodulation, Mast Cells, and Long Covid
Using Light to Heal?
Photobiomodulation is the use of specific types of light to affect living organisms… A large body of research shows that light can destroy micro-organisms, reduce inflammation, improve blood flow, and have a variety of other beneficial effects. And certain frequencies of light can reduce mast cell activity, which seems to be an important part of the misery of Long Covid.
It was shown several years ago that people with chronic sinus issues tend to have hyperactive mast cells in the sinus tissues, and that bathing the sinuses in red or near-infrared (NIR) light reduces congestion and other symptoms while also reducing mast cell hyperactivity. The light treatment reduced histamine release and a variety of other inflammatory compounds.
“Local (but not systemic) photobiomodulation treatment reduces mast cell degranulation, eicosanoids, and Th2 cytokines in an experimental model of allergic rhinitis.” Lasers in Medical Science, Apr 2022, PMID 34731332.
One important point is that the beneficial effect is local - the sinuses had to be lit up to see improvement. If the light was applied to other parts of the body, the mast cells in the sinuses remained hyperactive and they kept on dumping more histamine and other inflammatory compounds.
In the case of Long Covid, this would mean that mast cells in the stomach, lungs, and other areas might need to be illuminated. We know that most people who display Long Covid symptoms have increased mast cell activity, but we don’t know exactly which tissues contain the most hyperactive mast cells.
So is it possible to get enough light into the body to make a difference? Yes. Probably.
Light Wavelength: Penetration and Biological Activity
Shorter wavelengths of light (ultraviolet and blue) scatter more than longer wavelengths… and they penetrate much less. Ultraviolet rays are absorbed in a thin layer of the skin, which concentrates their activity (both good and bad) near the surface.
Ultraviolet and blue light is better at inactivating viruses and other microbes. It is also capable of damaging or killing human cells. UV can cause sunburn, and it can damage DNA (which can lead to skin cancer in the long run). UV and blue light are not generally recommended for D.I.Y. photo treatments (apart from possibly some limited sunbathing) — the risks from overexposure are significant. But red and NIR light is generally considered safe. The red/NIR heating pads that are available are considered low risk if used appropriately.
Red light penetrates deeper into tissue than UV and blue, and IR penetrates even more deeply. The power or intensity of the light source also plays a role in how deep light will penetrate.
Most of the early research on photobiomodulation was done using lasers. Lasers produce a coherent light - it doesn’t spread out the way that light from other sources does. That’s why we have laser pointers that hold a tiny dot even when 50 or 100 feet away from a screen, when the light from a flashlight might spread out to cover an entire wall and be very weak. This coherency makes it possible to target small areas with strong light. Lasers also typically produce a very pure light with a narrow frequency range (a single color), which made it possible to test the biological effects of different types of light.
Research has shown that red and infrared light from LEDs works mostly the same as light from red/NIR lasers. The biological effects are mostly dependent on the wavelength and intensity, not on the coherence of the light. LED generated light will diffuse or spread out much more - that is a negative if the goal is target one small area, but a positive if the goal is to light up entire organs with a bath of light.
Most of the studies on inflammation that used red/NIR light used wavelengths of 650 nm for red, and 850 nm for NIR, but these frequencies don’t seem to be fixed in stone - red and NIR, in general, tend to be anti-inflammatory, even if some wavelengths might be a bit better.
Do Infrared Saunas have the Same Effects?
The term ‘infrared’ is not very specific and can be confusing. It literally means that a wavelength is ‘beyond red.’ And there are actually two types of IR that are very different.
Near Infrared (NIR) is photon-based; it is a form of light. Our eyes don’t sense these types of photons the way they do with blue-green-red light, but the energy behaves a lot like particles.
Far Infrared (FIR) behaves more like electromagnetic waves. It is better to think of FIR as heat that can be broadcast from the heater to some object through space, without having to warm up the air or water in between.
Many of the infrared saunas out there rely on Far Infrared energy. This can make for a very nice sauna, where the heat penetrates the skin and heats the body more evenly than a traditional hot air (convection) sauna. Far infrared opens the blood vessels, it lowers blood pressure and promotes sweating and some of the biochemical changes seen with other types of heat bathing. But Far Infrared does not have all the anti-inflammatory properties seen with Near-Infrared.
Heat Lamps?
There are a variety of incandescent heat lamps that are used in the food services, in spas, and iguana tanks. Some of these give off photon-based IR, some give off only far infrared, and some give off both. If the bulb gives off visible red light, it is safe to assume it is also giving off some NIR. If it is a ceramic heater for aquariums, it is probably only far-infrared without any photons or NIR.
Some heat lamps work, but without looking at the spectral curve to see what type of energy they put off, there is no guarantee it will be effective. Heat lamps also have a greater risk to the body … they have to be close enough to bathe the tissues with light, but far enough away so that the heat they give off does not burn a person. LEDs are safer - they can be placed directly on the skin, they get the light into the body, and they don’t put off huge amounts of heat. Incandescent heat lamp bulbs burn out pretty quickly and can be expensive to replace, while LEDs can last for thousands or ten-thousands of hours.
Cost, Safety, and Effectiveness of Infrared Devices
I bought a red/NIR heating pad a few years back for around $100. It contains over 100 LEDs, and it has a built-in timer that runs for 20 minutes (the recommended maximum time to have it continuously over one spot without a break). If my back or neck is sore, or if my arthritic hands are bothering me, I use this.
Some of the relief from this type of treatment might be realized at the end of the 20 minute session - by that time, the tissue is warmed up and blood vessels are opened (and that involves both heat and an increase in nitric oxide triggered by red/NIR light). But for best results, it usually takes a few treatments over a few days. Some of the anti-inflammatory changes take time … the light leads to chemical changes, and genes turn on or off in response to the light … those changes are not immediate.
I bought a ‘BioNase’ device for my chronic sinus problems several years ago. It does provide some value when I use it regularly. My sinus issues are fairly entrenched - deviated septum, mouth breathing at night, chronic infections, etc etc. Part of the issue is that my blood pressure drops 20 points, I get sweaty, and my sinsuses clog up after a big meal … that points to mast cell hyperactivity in the gut with big dumps of so much histamine into the blood that it affects the sinuses even when local histamine release might be tamped down by the BioNase. I am thinking about red/NIR for the abdomen. But those with sinuses issues might benefit from this non-drug alternative. 1
One review of the use of PBM for sinus issues concluded: “… intranasal phototherapy appears to be safe and well-tolerated. Most studies demonstrated symptomatic improvement and quality of life scores.”
“Rhinophototherapy: gimmick or an emerging treatment option for allergic rhinitis?” Rhinology, Dec 2011, PMID 22125778.
A few months ago, my cat had a semi-urgent issue and my regular vet didn’t have any openings and I didn’t want to spend $500 for the animal ER, so I called around and found another vet who had an appointment open. In the treatment room, there was a poster advertising IR treatments for a variety of pet concerns. I didn’t ask, but I am guessing that a session costs $50 or more. I also spoke to a friend a few years back whose son was an athlete who had a muscle injury. The child was getting infrared treatments, and the parent was convinced that they helped.
I have browsed hundreds of research abstracts on PBM, and am convinced that light can have positive effects on our biology.
If the fee or co-pay for infrared treatment is $50 a session, it is easy to see that after 3 sessions, the amount spent would be equal to a decent LED device that offers unlimited D.I.Y. treatment.
Photobiomodulation and Acute Covid
There have been many articles in the medical literature suggesting that photobiomodulation might be useful for Covid - there is a strong rationale. There was one study that looked at the effects of light during the acute infection stage, and it suggested that light does help. The was not rigorously designed to prove the value — it was an initial exploratory study. But it does provide some information worth considering.
In a study of 50 patients with acute covid infections or immediately after infection, people were given a course of red and infrared light. Within 4 days of starting the light therapy, 41 of the 50 patients saw the elimination of fever, body aches, heavy coughing; lung congestion, difficulty breathing, sinus congestion, eye complaints, and extreme malaise. Oxygen saturation increased and none of the 50 went on to need supplemental oxygen.
“Whole-organ transdermal photobiomodulation (PBM) of COVID-19: A 50-patient case study.” Journal of Biophotonics, Feb 2022, PMID 34658147.
The researchers concluded that the acute inflammatory symptoms resolved within 4 days for all patients, but those who were not treated soon after diagnosis required more light treatment sessions to get full resolution of other chronic symptoms.
The standard response from many in the medical community will be “That’s very interesting, but it was a small study, it was not a randomized, double-blinded, placebo-controlled study; we need more research.” And they do have a point… we want to know for sure if the results that were reported are real and repeatable. But the red/NIR treatment is safe, it is low cost, and it did not replace standard care, it was an add-on or adjunct therapy. A hospital or insurance company might not want to spend millions of dollars on a therapy that ~might~ work, but a patient who is dealing with serious challenges to their quality of life might rationally spend $100 on something that is safe, affordable, and ~might~ work. And if doesn’t help with Long Covid symptoms, they still have a heating pad for aches and strains.
55 articles in the medical research deal with photobiomodulation and Covid or Long Covid. Most of them are related to the acute infection phase and the rationale related to that - there are many researchers who think that this approach has value, and they want to see that potential investigated. But there were some studies that actually involved testing the idea that light can help.
A Brazilian study looked at using red/NIR light to help with recovery in people who had lost their sense of taste. They concluded that the treatment seemed to be beneficial, but this study didn’t really compare the 10 patients who got laser treatment to others who did not — this raises questions about whether the treatment really had and effect - maybe they would have recovered their sense of taste just as fast if nothing was done.
“A Brazilian multicenter pilot case series on the efficacy of photobiomodulation therapy for COVID-19-related taste dysfunction.”
The Bottom Line
The evidence points to red and NIR light as safe, especially when using LED light sources for reasonable lengths of time on each part of the body. The cost is not high. The evidence suggests that it might provide some help with long Covid symptoms, but that is preliminary evidence of effectiveness and not iron-clad proof.
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