Blood in Korean Medicine: How It Is Made, What It Does, and Its Bond With Qi

Blood is the second of the three basic substances of Korean Traditional Medicine (KTM), the traditional healing system of Korea also known as Hanbang (한방), after Qi. It is the easiest of the three to picture, because Blood (血) is the same red fluid we already know. But in KTM Blood is a little more than that — it is nutritive Qi and Body Fluids carried together within the vessels — and what makes it worth a closer look is how it is made, what it does, and how tightly it is bound to Qi. This article builds directly on the companion piece on Qi.

What Blood Is, and How It Is Made

The raw material of Blood is food. The purest essence the body draws from what we eat — the food essence (水穀精微) — is the stock from which both Blood and Body Fluids are made. The organ most responsible for turning food into Blood is the spleen-stomach, which refines that essence in the first place.

But the spleen does not work alone. The kidney plays the next most important role, in two ways. First, the kidney’s original Qi kindles and drives the spleen’s transforming work — which is why, even when we are depleted and have barely eaten, there is still enough reserve to eat and digest: the kidney’s banked Qi lets the spleen keep working. Second, the surplus left after Blood and Qi are made is stored in the kidney as essence (精), and from that essence Blood is made again. This is the old principle that essence is stored in the kidney while Blood is stored in the liver, and that the two continually generate and convert into one another — liver and kidney drawn from one source.

Finally, the heart and lung complete the process. Nutritive Qi and Body Fluids seep together into the vessels, and only after passing through the lung and heart are they transformed into Blood that can actually nourish the body. Without the work of the heart and lung, Blood cannot function as Blood.

What Blood Does: Nourishing and Moistening

Blood has two linked jobs: to nourish and to moisten. Because Blood supplies nutrients to every organ, a person survives and stays well on it; movement and the senses alike depend on Blood to nourish and moisten them. The mind depends on it too — and here is a useful detail: mental activity, being still rather than physical, draws mainly on Blood rather than Qi. When Blood’s nourishing and moistening work flows well, the signs are visible and felt: skin and hair turn lustrous, the mind settles, and complaints such as nervous exhaustion, forgetfulness, and insomnia ease.

How Blood Moves

Blood does not move itself; it moves on Qi. Its circulation depends on two functions of Qi working together — propulsion, supplied mainly by the heart and lung, and containment. Propulsion drives the Blood along; containment keeps it from leaking out of the vessels. And when Blood reaches a tissue that needs it, the nutritive Qi and Body Fluids it carries pass out through the vessel wall into the tissue — a release that the containing function itself regulates. Movement and holding, again, are a balanced pair.

Blood and Qi: An Inseparable Pair

If the Qi article emphasized anything, it is that Qi and Blood cannot be understood apart. The relationship runs in both directions. On the side of Qi: Qi generates Blood — its nutritive form (營氣) turns Body Fluids into Blood and is itself an essential ingredient of Blood — and Qi moves Blood, through the same propulsion and containment described above. On the side of Blood: Blood is the mother of Qi, its house. Because Qi is formless and restless, it has to ride on something formed to travel without being lost, and that something is Blood — Blood is “the house of Qi” (血爲氣之府). The clinical consequence is direct: when blood is lost, Qi leaks out along with it, which is why heavy bleeding drains a person’s strength so fast.

The same logic ties Blood to Body Fluids, since the two share one origin in the food essence the spleen-stomach extracts. They behave similarly and convert into each other easily; the difference is mainly where they sit — Blood inside the vessels, Body Fluids outside them — and whether nutritive Qi has joined in. In that sense Blood is nutritive Qi and Body Fluids combined.

In Summary

Blood is the familiar red fluid, and at the same time nutritive Qi and Body Fluids carried together in the vessels. It is made from food essence by the spleen-stomach, kindled and replenished by the kidney, and finished by the heart and lung; it nourishes and moistens the whole body and the mind; it moves only on the propulsion and containment of Qi; and it is bound to Qi as a mutual pair — Qi making and moving Blood, Blood housing and carrying Qi. With Qi and Blood in view, Body Fluids and the organ theory that follows fall into place.

Related reading: Qi in Korean Medicine · Filling Organs vs. Emptying Organs

This article reflects the clinical observations and teaching practice of Professor Seungho Baek, Professor of Korean Medicine at Dongguk University College of Korean Medicine, specializing in Pathology and Oncology.