Improve Your Lymphatic System for Overall Health & Appearance

Andrew Huberman, who introduces himself as a professor of neurobiology and ophthalmology at Stanford School of Medicine, opens the episode on the lymphatic system by admitting that the topic can sound esoteric. For many listeners, he says, it brings to mind talk of "lymphatic clearance," very light massage that seems bizarre, jade rollers, or bouncing on trampolines.

His research for the episode led him to three general conclusions. The first is that the system is essential to health now and over the long term. The second is that it is "somewhat cryptic" and gets less attention than the cardiovascular system, the brain and nervous system, or even the gut microbiome. The third is that lymphatics often get "kind of a bad rap," because the wellness practices linked to them, such as rebounding on a trampoline or shaking, can look goofy, odd or "woo," largely because few people do these things every day.

First of all, your lymphatic system is absolutely essential to your immediate and long-term health.

Huberman argues that once listeners understand the structure and function of the system, they will see why rebounding, treading water and specific ways of breathing "actually serve the lymphatic system quite well," and that these practices have a real basis. In the same passage he also signals that some tools and treatments "perhaps should be avoided," so his position is not a blanket endorsement of everything sold under the lymphatic label.

He ties the lymphatic system directly to appearance. His example is the face after a poor night's sleep, or even right after waking from a good one: bags under the eyes, heaviness in the face, a groggy and older look. A couple of hours later the same face can look fresh, without any cosmetic help. He attributes that change to "lymphatic clearance" and to the lymphatic system of the face and neck, and says the explanation comes later in the episode.

He then lays out what the episode will cover: how the system works, how to support it for short- and long-term health and for appearance, and how to support it after an injury or during cancer. He also previews a claim he returns to later, that the lymphatic system is "one of the major reasons" exercise supports longevity, heart health and brain health. He says the podcast is separate from his teaching and research roles at Stanford and that the episode includes sponsors.

Before turning to lymph, Huberman gives what he calls a very broad description of blood circulation, and says a full episode on heart health will come later. He describes two jobs for the heart: delivering oxygenated blood to every tissue and organ, and returning non-oxygenated blood to the heart and lungs so it can be oxygenated again.

In his account, arteries are fairly large tubes with walls that can withstand the high pressure needed to push blood out to the fingertips and toes. The blood carries more than oxygen: it also carries glucose, hormones, proteins and amino acids. Arteries narrow into arterioles and then branch into capillaries, whose walls are "just one cell thick." That thinness is what lets oxygen and nutrients leave the blood and reach the cells. He says he will explain the mechanics of that transfer at a future date.

Cells in any tissue, whether brain, muscle or liver, use these supplies and produce waste: carbon dioxide, physical cellular debris, metabolites and ammonia. This waste is pushed into the extracellular space, which he also calls the "interstitial space," the area around the cells. He points out that a lot of water also leaves the blood vessels during delivery.

Some of the water and waste, including carbon dioxide, is taken back up by venous capillaries. These are also one cell thick and feed into larger tubes and then veins, which return blood to the heart and lungs. He notes, and sets aside, the rare arteries that carry non-oxygenated blood, such as those going to the lungs, and defines the pulmonary system as the part of circulation directed toward the lungs. When you exhale, carbon dioxide leaves the body; when you inhale, new oxygen binds to hemoglobin and the loop starts again.

His takeaway for listeners who "only captured 5% to 10%" of the explanation is that blood circulation sends out oxygenated material, brings back material that carries a lot of waste, and involves a great deal of water throughout.

Huberman places the lymphatic system at the interstitial space, between the arterial system that delivers oxygenated blood and the venous capillaries that collect deoxygenated blood and waste. He describes it as "a series of tubes" that catch excess fluid and waste and also return them to the heart. He anticipates the obvious question of why a third system is needed if blood circulation "sounds nearly perfect," and answers that blood circulation is not perfect.

In his description, the lymphatic system takes the fluid left in the extracellular space, along with proteins, ammonia and carbon dioxide from cell metabolism, and returns it to the blood. Along the way it checks for contaminants such as bacterial or viral infections. That checking happens in the lymph nodes, which he defers to later in the episode.

Leaving immune monitoring aside, he stresses drainage alone. He puts the excess interstitial fluid at "about three to four liters" and calls clearing it "absolutely crucial." His reasoning is that a buildup of fluid, amino acids and cellular waste invites infection, since bacteria grow well in warm, amino acid-rich environments. It also invites inflammation from carbon dioxide, ammonia and other waste. He says inflammation can lead to tissue buildup, with adipose tissue and skin thickening and becoming chronically inflamed. He calls this fairly common in people who are obese and in people who don't move enough, and promises to explain why.

He says drainage matters for everyone, "healthy or unhealthy," and not only for people with obesity. He describes lymph as a semi-viscous, sticky fluid, "not superfluid" and "not a gel." It contains waste products, rarely red blood cells, often a few white blood cells, and other material.

He makes strong claims about what happens when clearance fails. He says the body quickly goes into local or systemic inflammation, and that poor lymphatic clearance in the brain produces "brain fog" and cognitive impairment. He says this can come on after a single poor night's sleep and describes it as severe: trouble holding a thought and feeling somewhere between asleep and awake. This section gives no specific study for these claims.

He ends this part by saying that, before discussing immune surveillance, he will cover what people can do to encourage the collection and drainage of extracellular fluid and waste.

The episode includes two sponsor reads. In the first, Huberman promotes LMNT, an electrolyte drink with sodium, magnesium and potassium and no sugar. He says even slight dehydration can reduce cognitive and physical performance. He drinks 16 to 32 ounces of water with an LMNT packet when he wakes up, and again during exercise, especially on hot days. In the second, he promotes David protein bars, which he says contain 28 grams of protein, 150 calories and zero grams of sugar, with 75% of calories from protein. He says this helps him reach his goal of one gram of protein per pound of body weight per day. These are advertisements, not part of the lymphatic argument.

Huberman says the lymphatic vessels, "basically just tubes" of different sizes, get too little attention compared with the lymph nodes. Doctors feel the nodes under the jaw, in the armpits and where the legs meet the groin. He adds that dull pain or swelling there is not necessarily a sign of a systemic infection, though it could be. The vessels themselves, he says, reach every tissue, from the toes to the brain, skin and fat. A map of them "would just look like spaghetti everywhere." He describes lymph nodes as larger compartments where lymph is held for a while, monitored for infection and then passed along.

The key structural property he emphasizes is that the vessels are one-way: fluid can pass through them in only one direction, toward the heart. He defines "lymphatic flow" as fluid passing from the interstitial space into these vessels and then back into the venous blood. He notes that "lymphatic ducts" is a technical term for something else, which is why he avoids it for these vessels.