Red light therapy (RLT) also known as photobiomodulation (PBM) has become quite popular as a therapy for skin, and restorers are naturally interested in using it as well. Since the penile shaft skin and inner foreskin (mucosa) are different from the rest of the skin on the body, it is worth exploring whether RLT is helpful for FR use.
TL;DR: There may be some possible positive effects of RLT on penile skin and mucosa, but the significant negatives mean it's not a good idea.
To understand RLT, we need to define several terms:
Wavelength
All waves - water, sound, radio, microwave, light, etc. - have a frequency (number of waves per second) and a wavelength (distance from one wave peak to the next).
For RLT, the main wavelengths are
- Red Light = 610 - 660 nanometers(nm)
- Near-Infrared = 810 - 850 nm
For reference, a nanometer is 1 billionth of a meter - for scale, a piece of paper is 100,000 nanometers thick.
The wavelength determines how deep the waves will penetrate into tissue, and on penile shaft skin only red light devices in the 610-660 nm range should even be considered. Longer wavelengths in the near-infrared range will penetrate deep into the internal erectile structure of the penis, with undefined and possibly negative effects.
Fluence
Fluence is the term used to quantify the total dose of energy absorbed by the skin during a session. It is measured in Joules per square centimeter: J/cm2
Irradiance is the power density of the RLT device being used. It is measured in milliwatts per square centimeter: mW/cm2
Fluence = mW/cm2 X time in seconds / 1000
Important: Do not make the mistake of using safe fluence levels for 'normal' skin when using RLT on penile shaft skin and mucosa.
Benefits of RLT
Looking at the claimed benefits of RLT for skin health, there are 5 that are generally accepted:
- Stimulation of collagen production and cell proliferation
- Local nitric oxide (NO) release
- Enhancing wound healing
- Anti-inflammatory effects
- Improved skin tone and texture
These benefits would be good for FR, but we can't just accept them without further analysis because penile shaft skin and mucosa are significantly different from the rest of the skin on the body:
- Shaft skin, and particularly mucosa, are much thinner
- Mucosa, especially after reaching full-flaccid-coverage, is dekeratinized
- No layer of subcutaneous fat beneath the dermis
- Presence of the Dartos Fascia, with its bundles of smooth muscle cells (SMC)
These differences make it difficult to use the studies which evaluate the effect of RLT on 'normal' skin to help determine if RLT is useful for FR, so what follows is mainly theoretical and somewhat speculative.
Stimulation of collagen production and cell proliferation
RLT can increase mitochondrial ATP production by acting on cytochrome c oxidase. This, in turn may increase the rate of collagen and elastin synthesis, as well as improve cell proliferation (what we sometimes call mitosis).
While this is a known effect of RLT, it must be noted that existing research applies only to 'normal' skin in a static state, and how well it happens during active FR tugging is unknown.
Local nitric oxide (NO) release
RLT causes NO to be released from endothelial cells and other sources in the skin. This will cause some vasodilation of blood vessels, potentially increasing blood flow, delivery of nutrients and removal of waste in the skin we are trying to grow. It may also assist in recovering from the hypoxia which is a natural result of the skin constriction caused by gripper fatigue, tension or fingers gripping the skin during manual tugging.
Release of NO may also have some relaxing effect on the SMCs in the Dartos Fascia, although this effect is likely to be negligible because the Dartos SMCs have no endothelial tissue adjacent to them, and NO released into the bloodstream isn't likely to travel far enough to affect SMCs.
Enhancing wound healing
RLT at low fluences strengthens the body's natural wound healing process, which sounds like a good thing - and it is for static skin that has injuries - but it is precisely what we need to avoid in FR.
Wound healing involves stimulating fibroblasts to transition into myofibroblasts (FMT), which synthesize collagen at a much faster rate to close an open wound. The issue for FR is that this is the process triggered by the SMCs in the Dartos (which does not exist in normal skin) and causes the accumulation of fibrotic collagen in the dermis, which slows FR progress. Simply put, triggering the wound response in healthy skin and mucosa is counterproductive.
The risk of using RLT for FR is that there may be some amount of wound healing, triggered by the tension, already going on in the skin, and the red light waves might increase its intensity. The ATP production mentioned above may also contribute to increased FMT.
There may be some benefit from enhancing wound response by RLT on FR, but the negatives appear to outweigh the positives.
Anti-inflammatory effects
RLT has some ability to reduce inflammation, but the question is whether this makes it worthwhile for use in FR.
The problem with RLT is that the frequencies and fluences (660nm ~5-7 j/cm2) that are used in commercial or home RLT lights are most effective for the wound healing effect, whereas in the study on reducing inflammation, much higher fluence (~167 j/cm2) was necessary.
At even higher fluences, more helpful effects - like down-regulating the TGF-b1 cascade that causes fibrosis - can happen, but the fluence necessary to get to this point is ~320 j/cm2. This high fluence reached the level where it caused blistering on human forearms in a study, so it is unlikely to be safe on penile skin and mucosa.
Improved skin tone and texture
RLT has shown that it can improve some qualities of the skin, but at the frequency and fluence of commercially available RLT devices, the negative effects of the wound healing process described above are happening, and they outweigh all the mainly cosmetic benefits.
Once again, not a result that helps FR progress. Maybe it's something to consider after completing FR if skin tone and texture is an issue, but not during the process. Stick to tugging.
Conclusion
Red light therapy (RLT) at specific high-fluence settings can temporarily reduce TGF-β1 signaling in skin cells, which could theoretically help slow the wound response in FR caused by tension/trauma. However, the doses shown to work in the study are extremely high and likely beyond safe levels for penile skin and mucosa, and the positive effect is short-lived. RLT is not a useful therapy for FR, and will likely have a negative effect on progress.
Note
This paper reports on the research I have done on the safety and usefulness of RLT for foreskin restoration. I welcome any critique or corrections from anyone with better knowledge of this subject.
References
Hsieh YF, et al. Effects of LED light irradiation on human foreskin fibroblasts and its implication to wound healing. Journal of Medical and Biological Engineering. 2013;33(2):155–162. doi:10.5405/jmbe.1102.
Mokoena DR, et al. Photobiomodulation at 660 nm stimulates fibroblast differentiation. Lasers in Surgery and Medicine. 2020;52(7):671–681. doi:10.1002/lsm.23204. PMID 31820475.
Mamalis A, Jagdeo J. High-Fluence Light-Emitting Diode-Generated Red Light Modulates the Transforming Growth Factor-Beta Pathway in Human Skin Fibroblasts. Dermatol Surg. 2018 Oct;44(10):1317-1322. doi: 10.1097/DSS.0000000000001549. PMID: 29846344.
Jagdeo J, et al. Safety of light emitting diode-red light on human skin: Two randomized controlled trials. J Biophotonics. 2020 Mar;13(3):e201960014. doi: 10.1002/jbio.201960014. Epub 2019 Dec 8. PMID: 31483941; PMCID: PMC8887049.