The Peter Attia Drive - #326 - AMA #65: Red light therapy: promising applications, mixed evidence, and impact on health and aging

Episode Date: November 18, 2024

View the Show Notes Page for This Episode Become a Member to Receive Exclusive Content Sign Up to Receive Peter’s Weekly Newsletter In this “Ask Me Anything” (AMA) episode, Peter dives into the world of red light therapy in response to frequent questions from listeners. Peter provides a comprehensive exploration, starting with the basics of red light therapy and why it’s getting so much attention. The conversation examines the latest data on various applications, including aging, skin health, acne, wound healing, hair loss, eye health, exercise performance, metabolic health, weight loss, inflammation, injury recovery, and menstrual cramps. Peter analyzes the scientific literature on each use case and concludes with a summary table that provides an easy-to-follow breakdown of the potential benefits of red light therapy across these areas. If you’re not a subscriber and are listening on a podcast player, you’ll only be able to hear a preview of the AMA. If you’re a subscriber, you can now listen to this full episode on your private RSS feed or our website at the AMA #65 show notes page. If you are not a subscriber, you can learn more about the subscriber benefits here. We discuss: Overview of topics and the motivation behind exploring red light therapy [1:45]; The basic science of red light therapy [3:15]; The unique penetration properties of red light [6:00]; What happens when tissue is exposed to red light [9:30]; Exploring red light therapy’s potential to combat aging [11:00]; Red light therapy for treating acne [13:00]; Red light therapy for aiding in wound healing [18:45]; Red light therapy for hair loss: promising benefits and practical advice [24:15]; Analyzing the evidence of a positive or negative effect of red light therapy on the eyes [28:00]; Red light therapy’s impact on performance and recovery [30:30]; Red light therapy’s impact on metabolic health: analyzing the limited evidence for improved glucose metabolism [32:45]; Red light therapy for weight loss and targeted fat reduction [36:45]; Red light therapy for inflammation, chronic pain, and injury rehabilitation [41:00]; Red light therapy as a treatment for menstrual cramps [43:45]; Summary: promising applications of red light therapy, unsupported claims, and costs to consider [46:45]; and More. Connect With Peter on Twitter, Instagram, Facebook and YouTube

Hey everyone, welcome to a sneak peek, ask me anything or AMA episode of the Drive Podcast. I'm your host, Peter Atiya. At the end of this short episode, I'll explain how you can access the AMA episodes in full, along with a ton of other membership benefits we've created. Or you can learn more now by going to peteratiamd.com forward slash subscribe. So without further delay, here's today's sneak peek of the Ask Me Anything episode. Welcome to Ask Me Anything episode 65. I'm once again joined by my cohost, Nick Stenson. In today's episode, we cover red light therapy as a topic we get asked about all the time. In fact, my wife

asked me about it all the time. So it was clear that it was time for an AMA. In this conversation, we lay the foundation for what red light therapy is and why there is such an emphasis on it. We then break down the various forms of red light therapy and their various treatments into whether or not I think they are beneficial. In other words, we go through each application and review the data for them. So these include red light therapy for aging in general, skin health and acne, wound healing, hair loss,

eye health, exercise performance and recovery, metabolic health, general weight loss, spot fat loss, inflammation, injury rehab, and menstrual cramps for women. So in other words, we go through each of these and do a detailed analysis of the literature. We close this conversation by summarizing my overall takeaways for each use case and explain via a summary table that we created that breaks down everything you might want to know to understand this. If you're a subscriber and you want to watch the full video of this podcast, you can find it on the show notes page. If you're not a

subscriber, you can watch a sneak peek of the video on our YouTube page. So without further delay, I hope you enjoy AMA number 65. Peter, welcome to another AMA. How are you doing? Good, thanks for having me back. Anytime, anytime. So today's AMA, we are gonna focus on a single topic, which is red light therapy. This is something we get asked about a lot,

not only questions from the website and subscribers, but I know through your patients as well. And so we compiled all these questions and through this conversation, hopefully going to cover what red light therapy is, how it can work, deep dive into some various claims out there around red light therapy. This can include potential effect on skin health, wound healing, hair loss, eyesight, exercise performance and recovery, metabolic health, fat loss, inflammation, chronic pain, and a lot more. So with all that said, anything you want to add before we get rolling into it.

Two unrelated things. I noticed you have a little visitor for the podcast today, hanging out with you there. Hopefully he's interested in this is something he'll like. And secondly, I would add that my wife is specifically asking me these questions. So she's very keen to buy a whole bunch of red light things. And I asked her to just hold off until we did the research for this episode so that we could at least have a sense of if there's value there where it is. I don't know if she's a subscriber though. So if she's not,

this might be the one that she subscribes for. I respect that when your wife asks you medical questions, you say, let me send you a podcast episode instead of telling her the answer like everyone else. So it's good to know you practice what you preach, even through your direct family. Okay. First question. I think it's going to be helpful to just explain when we say red light therapy, what does that even mean? Yeah.

You can't do this without at least having some understanding of the physics and the principles that define light and waves come up over and over and over again, as you try to evaluate the plausibility of the claims that are made here. When we're sitting here looking out at the world, we're looking at light and there's visible colors of light. Maybe I should take a step back. Light exists as waves and they're very short waves to be clear. Sound waves are really, really long.

Light waves are really, really short. Then obviously, waves can get much, much shorter and you can get into UV, which we've talked about in detail on a previous podcast. And then even shorter than that would be X-rays and then even shorter than that are gamma rays. So as wavelengths get shorter, the energy gets more powerful. But if we just focus on light, visible light runs the gamut from about 380 nanometers, which should be purple-ish, and then all the way at the longest end, about twice that,

780 nanometers, is where red light is. When people talk about red light therapy, they're mostly talking about light that is in that very narrow band. So for example, again, a white light is giving you all mixed across that entire range. Red light would be more narrowly focused. It's also important to understand that, and we'll talk about this a little bit today, phototherapy in general involves wavelengths across that entire band of visible light, but it also includes something called near infrared. So that basically runs the gamut from about 400 to 1100 nanometers. So I think the easiest way to think about this is red light therapy, which runs about 620 to 780

nanometers and then near infrared, which is right adjacent to that. The next thing up in terms of length, which is about 790 to 1400. So again, if you forget everything else, just remember when people talk about red light therapy, they're talking about wavelengths that are just in that red visible area of 620 to 780. Then often they talk about near infrared as well, which is not visible to be clear, you don't see it, but it's just a little bit longer, 790 to 1400 nanometers. We'll come back to this over and over again because there are some instances where the fact that you can't see it might actually make it a little more dangerous.

Double clicking on red light therapy, can we explain a little bit more about what is special about it and why there's so much emphasis on it as talked about for the various claims that we'll speak about today. People who listen to our podcast on ultraviolet light may recall a distinction I made between UVA and UVB, which came down to the degree of penetration. And so similarly, when you think about red light therapy, and you remember that the longer a wavelength, the more it can penetrate, albeit with less energy. What makes red light interesting is it is sort of at this sweet spot where it

has some capacity to penetrate more so than other forms of visible light. That's sort of part of what makes this interesting. Now the exact depth that's reached by the red light or the near infrared is a function of how the light beams are organized. What is the amount of coherence, which is how much do the wavelengths line up with each other? If the wavelengths are all coherent, the peaks and valleys are in the same place. It's going to have more penetrance.

Then what's the extent to which they're all aligned in the same place. It's going to have more penetrance. Then what's the extent to which they're all aligned in the exact same direction? That's called collimation. In other words, the light isn't spreading, but rather it's all pointed in the exact same direction. Then finally, you have the intensity. We'll talk a little bit about the difference between watts and joules because if people are looking at these devices, sometimes they give you information in watts and sometimes they give you information in joules, which of course, there's a very clear relationship between them. And of course, broadly speaking, energy matters as well. So when you take all of that into account, though, the really important principle that

I think it's perhaps missed when people evaluate these things is that for the most part, red light can't penetrate nearly as much as people is that for the most part, red light can't penetrate nearly as much as people think it can. Okay, if red light is being delivered by LEDs, which is the most common way that it is, it's going to be able to penetrate about two to three millimeters into skin. Now, infrared light can go a little bit deeper because remember it's a longer wavelength and it can reach probably five to 10 millimeters. Now, infrared light can go a little bit deeper, because remember it's a longer wavelength, and it can reach probably five to 10 millimeters.

Now, if red light is delivered by a laser, because again, you now have a more focused form of light energy, it could penetrate significantly higher than that. It could go from one to four centimeters. So again, keep in mind, the way that the light is organized plays a significant role in the

depth that it can penetrate. Now if you start to think about some of the applications we're going to talk about when you start to think about red light therapy, just keep in the back of your mind if something can only penetrate one to three millimeters, it's going to be difficult for it to have some of the profound effects that are sometimes claimed. Even if something can penetrate 10 millimeters or a centimeter, which would be quite deep, it's not clear that that's going to be able to have a significant effect.

So, as a general rule of thumb, the more superficial the application, the more plausible I think it's going to be as we go through these. Last foundational question before we get to the various claims and where this could be beneficial or not is, in general, what happens when the tissue is exposed to red light? This is an important and, as you said, foundational question. So to have any biologic effect, the light needs to be absorbed by some photosensitive molecule within the cell or tissue that it's hitting. And so the absorption of light by these photosensitive molecules, which are called chromophores, cause a localized chemical change or a photochemical reaction. Now, the most interesting of these is

probably something called cytochrome C oxidase or CCO. It's a component of the electron transport chain within mitochondria. And generally speaking, most people who are proponents of red light therapy point to cytochrome C oxidase or CCO as the main target and therefore the mediating effect of the biologic impact of red light. So red light and near infrared wavelengths do seem to excite cytochrome C oxidase and its activity then increases subsequent ATP production. Conversely, blue and green wavelengths, remember these are shorter, less penetrant but more powerful, seem to decrease the activity of CCO and subsequently decrease ATP production. Now kind of getting into various claims of where red light therapy can be beneficial

or not, I think it'd help to maybe start with what do we know about the of where red light therapy can be beneficial or not. I think it'd help to maybe start with what do we know about the idea that red light therapy can combat aging as a whole. Thank you for listening to today's sneak peek AMA episode of The Drive. If you're interested in hearing the complete version of this AMA, you'll want to become a premium member. It's extremely important to me to provide all of this content without relying on paid ads. To do this, our work is made entirely possible by our members, and in return, we offer exclusive member-only content and benefits above and beyond what is

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