Science Friday - What is lymphatic drainage, anyway?

Episode Date: September 18, 2026

There’s a new wellness trend focused on an obscure capillary system that moves fluid around the body. Things like lymphatic walking, vibration plates, and compression boots have been touted as ways to stimulate the lymphatic system to combat bloating, flush away toxins, and generally promote health. So what is the lymphatic system, and what does it do? And is there anything to these claims? Flora gets some answers with the help of two experts: Timothy Padera, a researcher who has dedicated his career to better understanding how the lymphatic system works; and physical therapist Marc Miller, who treats cancer patients with manual lymphatic drainage. Guests:Dr. Timothy Padera is an investigator at Mass General Research Institute and a professor of radiation oncology at Harvard Medical School. Dr. Marc Miller is a certified lymphedema specialist and senior physical therapist at UT MD Anderson Cancer Center. Transcripts for each episode are available within 1-3 days at sciencefriday.com.  Subscribe to this podcast. Follow our show on Instagram, TikTok, Facebook, and Bluesky @scifri and sign up for our newsletters. Got a science question that’s keeping you up at night? Call us: 877-472-4374 Hosted by Simplecast, an AdsWizz company. See pcm.adswizz.com for information about our collection and use of personal data for advertising.

Hey, it's Flora and you're listening to Science Friday. A new wellness trend focused on an obscure capillary system that moves fluid around the body has been bubbling up. And you all wanted to know more. I am calling with questions about lymphatic drainage. In regards to lymphatic drainage, I'm not even quite sure what that means. I heard that jumping on a rebounder helps your lymphatic system. work better and you feel more healthy. I've gotten a lymphatic drainage massage before, and I didn't really feel any different.

Lymphatic walking, vibration plates, compression boots all have been touted as ways to stimulate the lymphatic system to combat bloating, flush away toxins, and generally promote health. So let's dive in. What is the lymphatic system? what is it do in the body, and is there anything to these claims? Here with answers are two experts. We have Dr. Timothy Padera, a researcher at Mass General Research Institute, who's dedicated his career to better understanding how the lymphatic system works,

and physical therapist Dr. Mark Miller, who treats cancer patients with manual lymphatic drainage at UTMD Anderson Cancer Center. Tim, Mark, welcome to Science Friday. Yeah, thank you for having me. Yeah, ditto, thanks. Thank you for being here. Tim, let's start with some 101. What is the lymphatic system and what does it do?

So the lymphatic system really is comprised of many different types of vessels that are all throughout our body. They cover the surface of our brain. They're in the tips of our toes. They're sort of pretty much in every tissue in between. And they also contain critical organs for generating our immune responses called lymph nodes. And there's really three main functions for the lymphatic system. The first is it really does help maintain our fluid levels in our tissues. And so some of the smaller lymphatic vessels will sit in the tissues, absorb fluid,

and that gets collected by larger vessels that end up returning that fluid called lymph back to the blood. A second main function is that the lymphatic system kind of forms communication between our tissue and our immune system. And so as those small vessels are taking up the fluid from the tissue, they can also pick up bits of bacteria or virus or any other infection and immune cells. And they bring that information to the lymph nodes. So the lymph nodes can then determine whether they need to mount an immune response to anything, any sort of infection that might be happening.

And then the third main function is the lymphatics in our gut are really important for absorbing our dietary lipids. That's interesting. It seems to have varied roles. And so these vessels, they're not blood vessels. They're a different kind of vessel? They are a different type of vessel. So the blood circulation is sort of referred to as closed.

Like, we want to keep the blood in the blood vessels. And so the blood circulation also has this nice central pump on it. We call it the heart. Where the lymphatics really are just going one direction. They're going from the tissue to the blood, but it's not the blood coming really back in a closed system back to the lymphatics, right? So it's more like the roots from a tree absorbing fluid and bringing up to the trunk of the tree. And because there's no central pump to actually move the fluid, the larger vessels have their own muscle and can contract and actually

drive the lymph flow back toward the blood circulation. Tim, what is lymph? What's the definition? So I always say all lymph is local. Lymph is just the stuff in your lymphatic vessels, and it's comprised of whatever's in the tissue. So if you have inflammation in the tissue, it's going to be picking up all those inflammatory signals, bringing it to the lymph node. If you've been fasting for a long time, the lymph in your gut is going to look very different from if you've just eaten, you know, a cheeseburger, right? Because then you're going to get lot more lipids into that lymph. And so it's a very dynamic fluid and it's all sort of depends on the

tissue it's draining. You know, at any moment, lymph in different parts of your body is comprised in different things. Mark, you're a physical therapist and you focus on this. I think of the physical therapy as sort of rehabilitation for my back injury or my knee problem. What does it mean to be a physical therapist for lymphatic drainage? It can mean a variety of things, depending on your setting. For myself, I work in an oncology setting. Ninety-eight percent of my patients are cancer patients. Primarily breast is what I specialize in, but I do a lot of lower extremity as well. So my job is to help educate patients on the lymphatic system, to help bolster the lymphatic system through massage and compression. teach patients safe exercise to not increase swelling and not strain the lymphatic system,

and just to try to restore as much quality of life as possible after treatment for cancer, especially when that cancer affects to lymphatics. Mark, why do cancer patients need manual lymphatic drainage? Yeah, so the number one cause of lymphedema or a collection of lymphatic fluid into the tissues. in the world is a parasite called phyleriasis. Very common in Southeast Asia and some other locations. But the number one cause in America of lymphidema is treatment for breast cancer. So when lymph nodes are removed as a result of surgery, when they are damaged as a result of radiation that might be received, or even some types of chemos can start to flatten out the walls of the lymphatic vessels and decrease the contractility of those vessels and not allow them to,

send the fluid back to the circulatory system like they should, manual lymph drainage can help redirect that fluid in a positive manner and decongest some of those tissues and stimulate the lymphatics that are still functioning. What does lymphatic drainage mean? Manual lymphatic drainage is a very, very light massage used to stimulate the lymphatic vessels that were just being discussed to help direct the lymphatic fluid back to the circulatory system in the most expedient manner. you know, it was kind of really kind of put out there by influencers and celebrities. I think Jennifer Lopez was one of the first ones to kind of say, like, I'm going to get a manual lymphatic

drainage massage. It's great for my skin and it's great for a variety of other things. You said light massage. What does it feel like? It feels like a skin stretch. So if you were to just move the skin enough to stretch it or to wrinkle it and then let it snap back, that's about the pressure that we're using. So it's incredibly light. People have used other analogies like gently petting a kitten or moving the skin on a baby's head. Those are some other examples that have been used to try and teach the pressure, which can be difficult to master. Most of my patients ask me, is this actually doing anything? And we actually have studies that have been done at MD Anderson under a special type of camera that we can inject a dye and actually follow

the lymphatic fluid through these vessels and actually see it moving. So we know that the massage is actually moving the fluid through the vessels. Is there any benefit for people who don't have an illness related to the lymphatic system like lymphedema or had their lymph nodes removed? Like, is this helpful for healthy people? To my knowledge, there's no disadvantage to doing it. I'm not familiar with any research that is currently out there saying that, yes, by doing manual lymph drainage on healthy individuals, it's promoting X, Y, and Z. For manual emphatic drainage has been used in sports recovery in the past to help flush out some of the inflammatory markers that were previously being discussed, to help expedite recovery, to help decrease edema and inflammation in joints and in muscles, help flush out lactic acid, things along those lines. So in those particular cases, there has been research saying that it's helpful, but just Joe or Jane Smith going to a massage parlor and getting a manual lymphatic drainage from a certified lymphedema therapist.

I'm not aware of any studies out there that show a significant benefit in, say, skin health or anything along those lines. Tim, a lot of the lymphatic hacks online have to do with deep loading. Does that have anything to do with your lymphatic system? So I would say probably what's more important is the origin of where the bloating is originating, whether it's from inflammatory processes that are giving you the sense of that feeling of bloating, which could include more fluid or other things that are causing it. Maybe your diet, lack of sleep, can all sort of cause that. So it's not necessarily that the lymphatics aren't working or working properly that's leading to the bloating.

Now, lymphatics are good at removing fluid. So potentially stimulating lymphatics might remove some of that fluid and remove that sensation. But it's probably best to also think about the underlying causes for the bloating. Mark, I have to ask because we had a bunch of calls about it, what's the deal with these vibrational plates? Do they do anything? Should we all be bouncing? Look, in the lymphodema world, we have heard just about everything. Dry brushing used to be a big thing back in the day.

Vibration plates used to be a big thing. Rebounding used to be a big thing. There's no research to absolutely suggest that vibration plates improve lymphatic function. There's no research to suggest rebounding improves lymphatic function. I think what people typically give. get from the vibration plates and what people typically get from the rebounding is, they're getting the muscle pump. And because the superficial lymphatic vessels are so superficial, they're only a couple millimeters underneath the skin. You're getting that muscle pressing up against the skin. You're getting

that fluid being pressed up towards the heart back towards the circulatory system, as was previously mentioned. And I think it's probably helping in that area. But there's not been any research to show that no vibration plates or rebounding are actually beneficial in and of itself in isolation for the lymphatics. You know, this seems like an important system. I mean, obviously it's having a little bit of a moment online, but do you feel like it gets the recognition it deserves in the medical or research world? And I'd love to hear from you both on this. So it has been interesting that the field of understanding in the lymphatic system is really far behind what we know for the, cardiovascular system.

And I would say it was about the 1990s has sort of been the resurgence in lymphatic biology. And I think we're sort of now at a very unique time because we're starting to learn a lot more where we might start to be able to develop therapies for a lot of the different lymphatic diseases, lymphedema being one, but there's other diseases where lymphatic function could be improved that might help in a lot of different situations. There's been a lot of research recently on lymphatics that drain the brain and the role it might help in removing waste from the brain. And so you start thinking about things like neurodegenerative diseases, such as Alzheimer's.

People have been looking into the inflammation that occurs after traumatic brain injury and potentially by stimulating more lymphatic function, and being able to remove that to improve outcomes. Beautiful work on migraine headaches as well. And it's not just in the brain. These are all sort of diseases. There's been beautiful work looking at lymphatic drainage in the heart after myocardial infarctions. And so I feel like we're in this sort of window.

It's interesting that it's coming on sort of online as with the same time as a lot of these therapies are starting to potentially emerge. and obviously more research is needed, but for me, it's a really exciting time. Yeah, and I'll just piggyback on that. I'm just extraordinarily blessed to work with a plastic surgeon at MD Anderson, who this is a big part of his practice, big part of his focus. We are developing surgical techniques for lymphadenema to help restore this, and not only that, but in addition, we're doing a lot of the immediate lymphatic reconstruction and trying to bypass the lymphatics that are no longer there at the time of surgery.

So this swelling doesn't have a chance to occur. So a lot of these people hopefully never need to get to me and never need to see me. And that's becoming more of the norm now. And not only for breasts, but for melanoma and some other things as well. Dr. Mark Miller, certified lymphidema specialist and senior physical therapist at UTMD Anderson Cancer Center. Mark, thanks for joining us today. Thank you so much for having me. I appreciate it.

Tim, can you hang in the line? I want to ask you about what's next in the field of lymphatic medicine. Sure. Be happy to. Tim, do we have any drugs that target lymphatic system conditions like lymphedema? No. And, you know, to me, it's incredible. There are no FDA-approved drugs indicated to alter lymphatic function.

And when you compare that to like the cardiovascular system, we have drugs that can increase your blood pressure. lower your blood pressure, increase your heart rate, lower your heart rate. And right now we don't have anything for the lymphatic system. There's a lot of interest in doing so, and lots of research is being done to try and first understand how the lymphatic system works. And we're coming pretty far along in that. And now it's just about trying to develop molecular targets that can be drugs. that can then improve lymphatic function. I mean, Tim, you alluded to this, but are we yet harnessing the lymphatic system to help treat

other kinds of conditions? You know, like the way that we harness the immune system to fight cancer? Yeah, no. So that's a beautiful question, because there's theory on how improving lymphatic functions, say I sort of talked about brain drainage might improve things like, you know, the accumulation of the amyloid protein. and tau proteins and Alzheimer disease, right? That's a theory right now because we actually don't have a tool to test whether increasing lymphatic function could really improve those disease outcomes.

So to me, I think we're getting closer to being able to develop therapies that will show improvements in lymphatic function. We can then test them in sort of known lymphatic diseases like lymphedema, but also then think about them in these other disease processes where, lymphatic drainage might really help improve outcomes and symptoms and maybe long-term prognosis for a lot of these conditions. What is it like for you to work in this field that feels like it's really still in its infancy? You know, you can you can find a department of immunology at hospitals. You can find a department of cardiovascular medicine. Right now, there's no department of lymphatic medicine. And so I think there's a lot of opportunity to grow So, you know, when I got into this field, we were sort of right at the cusp of learning a lot more about lymphatic system from sort of how it works and in the biology behind it.

And to see the field develop over the last 30 years has really been incredible. There's tons of really smart scientists now that are invested in understanding the lymphatic system. I'm optimistic of where we will see sort of lymphatics and lymphatic medicine develop over the next years. Well, good luck. Thank you. Dr. Timothy Padera investigator at Mass General Research Institute and professor of radiation oncology at Harvard Medical School. This episode was produced by Shoshana Bucksbaum. Thank you to everybody who called in with your questions and your experiences.

And if you have questions for us, give us a call 877. for SciFry is our number. I'm Florida Lixman. We'll catch you next time.