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  • Ellen Brown L.Ac. DACM

San Jiao – Chinese medicine’s most mysterious “organ”

The San Jiao is an organ that does not exist in western medicine. Even in Chinese medical texts, its explanation is often vague, described as having a “name but no form” or location. Translated as the Triple Burner / Heater or Triple Warmer in English, it is said to connect the “upper, middle and lower” aspects of the body. Unlike other organs that are defined by their physical structure within the body, the best way to understand the San Jiao is to examine its function, which is to mediate the body’s water metabolism.

The San Jiao is not a single self-contained organ, but rather a functional energy system that helps to regulate the activities of other organs. It is composed of three parts, known as ‘heaters’, each associated with one of the body’s three main cavities: thorax, abdomen and pelvis.

Like connective tissue, it is said there is nothing the San Jiao does not envelope, including the vessels that hold Blood and conduct Qi. Functionally, the San Jiao is considered to be especially important in the process that allows optimal transportation of fluids in the body so that they do not build up. According to the ancient Chinese text, The Yellow Emperor’s Internal Classic, the San Jiao is compared to that of a sewage system of the body, “holding the office of sluices and manifesting as the waterways.” Put another way, the Upper Heater controls intake, the Middle Heater controls transformation, and the Lower Heater controls elimination.

There is no anatomical counterpart for this fu organ. Of the twelve zang-fu outlined in Chinese medicine, ten are associated directly with anatomical organs – Heart, Lungs, Liver, Spleen, Kidneys, Gall Bladder, Urinary Bladder, Large and Small Intestines. The eleventh, the Pericardium, is a type of space like its externally related partner the San Jiao. The Pericardium, however, is recognized in western anatomical and diagnostic studies, (it surrounds/protects the Heart) whereas the San Jiao is not. In dissecting a body, one would not be able to find a structure that could be called the San Jiao.


The integration of body, mind and spirit is essential to holistic healing practices of TCM. Early Taoist philosophers who were fundamental in establishing Chinese medical theory were intrigued with the trinitarian concept of body, mind and spirit. These philosophers articulated this trinity in terms of Heaven, Humanity and Earth to explain our connection to the universe. Superimposed on the body, the microcosmic system of this macrocosmic trinity parallels the San Jiao.

The San Jiao is a system comprised of three energy centers: the head, the chest, and the abdominal/pelvic region. The head is part of the Upper Heater and relates to Heaven; the chest comprises the Middle Heater, which relates to Humanity; the abdominal and pelvic regions comprise the Lower Heater and relate to Earth.


The Spirit is related to the Upper Heater of the San Jiao by virtue of the brain and the sensory organs of the eyes, ears and nose. According to Taoist teachings, the sensory organs of sight, hearing and smell are considered gateways and when 'opened' they allow for an awakening of perception to higher dimensions of consciousness.

In Chinese medicine, the head (due to its location on top of the body) is considered to be closest proximity to Heaven's energy above. This gives the brain a close relationship to the energy of Fire. Since the brain as an organ is supported by the Kidney organ system, it also relates to the element of Water.

This creates an interesting association of the brain as Fire and Water – two energies in opposition based on the control cycle in Five Element theory. Since the brain has aspects of both Fire and Water, a healthy balance of these two energies is required for optimal function.

The Upper Heater runs from the base of the tongue to the entrance to the stomach and controls the intake of air, food and fluids. It harmonizes the functions of the Heart and Lungs, governs respiration and regulates the distribution of protective energy to the body’s external surfaces.


The Middle Heater of the San Jiao is centered on the chest and is associated with the Spleen, Stomach, and, according to some texts, the Liver. Identified as a froth of bubbles, it is involved with digestion, absorption of essential substances, evaporating fluids, and imbuing Xue (Blood) with Nutritive Qi. The froth of bubbles refers to the state of decomposing, digested foods.

The Middle Heater runs from the entrance to the stomach down to its exit at the pyloric valve and controls digestion by harmonizing the functions of the Stomach, Spleen and pancreas. It is responsible for extracting nourishing energy from food and fluids and distributing it via the meridian system to the Lungs and other parts of the body.


The Lower Heater corresponds to the Kidney organ system and the Water element. Energetically, this level most closely relates to the health of the body itself. Water comes from the earth, so the energetics of the Lower Heater helps us gather energy from the earth to sustain our physical life.

Our Jing, or Essential Qi, is stored in the Kidney and corresponds on a cellular level to our genetic material, chromosomes and DNA. Telomeres, a segment of DNA at the end of chromosomes, are indicators of cellular health. As telomeres shorten, so does the lifespan of our genes, so we can see how the integrity of the genes and the process of aging relates to the abundance of Water energy contained by the body. In this regard, maintaining the health of the Kidneys, including the genitourinary and reproductive systems as a whole, is integral to maintaining the health of the physical body.

The Lower Heater, which is called the “drainage ditch” designates an area below the navel that includes the Kidney, Large and Small Intestines and Urinary Bladder.

The Lower Heater runs from the pyloric valve down to the anus and urinary tract and is responsible for separating the pure from the impure products of digestion, absorbing nutrients and eliminating solid and liquid wastes. It harmonizes the functions of the Kidney, Bladder and Large and Small intestines and also regulates sexual and reproductive functions.


From a Taoist perspective, maintaining the health of the Spirit is crucial to support the health of the Mind and Body. As Chapter 8 of the ancient text Ling Shu (Spiritual Pivot) states, "all diseases are rooted in Spirit." As the mind-body-spirit are rooted in the San Jiao, maintaining balance in the three Heaters is essential to having balance in body, mind and spirit.


Since the San Jiao is not viewed as an organ distinct from other zang-fu, it has are no actual patterns. Instead, patterns of the San Jiao are recognized by the patterns that affect the organs contained within each of the three Heaters.

Patterns associated with the areas of the San Jiao:

  • Patterns of Lung and Heart are the patterns of the Upper Heater

  • Patterns of Spleen and Stomach are those of the Middle Heater

  • Patterns of Kidney, Bladder, Small/Large Intestines are those of the Lower Heater

Still, particular patterns or disharmonies are clearly associated with the functions of certain acupuncture points on the San Jiao meridian.


The Upper Heater disperses and vaporizes fluids of the upper body. This function falls under the scope of the Lung dispersing function, and for this reason, the Upper Heater is compared to a "Mist".

In a disease state, the function of dispersion is usually blocked by an exogenous pathogen (Wind Cold or Wind Heat). This means that Defensive Qi circulation is impaired and the pores are blocked, manifesting as an invasion of Wind-Cold or Wind-Heat in the Lung.

When the San Jiao is attacked directly, usually by Wind-Heat rather than Wind-Cold, there will be sore throat, earache, mastoid pain, edema of the cheeks and yellow tongue coating.


The Middle Heater is compared to a “Maceration Chamber” because it digests food and drink (rotting and ripening). As such, its function is grounded in the Spleen / Stomach. Disorders of the Middle Heater are usually characterized by the excess accumulation and/or stagnation of food in the Stomach. When the Middle Heater cannot digest food, food retention causes belching, nausea, abdominal distention, bad breath and a yellow tongue coating.


The Lower Heater transforms, separates and excretes fluids and is said to be the "Drainage Ditch". Its functions are those of the Bladder, Kidney, Small and Large Intestines.

When in disease, the Lower Heater will often give rise to symptoms of Damp-Heat in the Small Intestine or Kidney Yang deficiency. Manifestation of any of these patterns will result in the dysfunction of urination or defecation (diarrhea) and a greasy yellow tongue coating.


The San Jiao has been poorly understood and a topic of disagreement for centuries in China. No wonder that it is hard to understand in the west.

Since the Yellow Emperor's Inner Canon (c. 200 BCE), TCM has held that the San Jiao energetic system is the largest anatomical structure in the human body, comprising a network of large cavities in the body trunk and the small interstitial spaces between the tissues and cells throughout the body. More than 2000 years later, according to recent scientific research in the west, this network of structures has been recognized by modern medicine.

Recently, western medical science reported that they have discovered a “new organ”, which they have named the interstitium. Interestingly, it is highly correlated in structure, function and distribution to the San Jiao which the Chinese have known about for centuries.

According to the scientists who “discovered” the interstitium, it is located almost everywhere in the body, but specifically just below the skin’s surface. It surrounds arteries and veins, encases the fibrous tissue between muscles and lines the digestive tract, lungs and urinary system.

The interstitium is described as a mesh – with a layer of fluid-filled compartments strung together in a web of collagen and a flexible protein called elastin. Scientists previously thought the layer was simply dense connective tissue.

The 2018 discovery of a “new” organ in our own bodies has created a fascinating link between ancient Chinese medicine and modern western medicine. The headline announced: Newfound "Organ" Could Be the Biggest in Your Body. Previously undetected, it was discovered by using a new method of examining living tissue microscopically. Before this method was available to us, the interstitium could not be examined because in post-mortem, the tissues would dry up after death and the interstitium collapsed.

The interstitium is a name for widespread, fluid-filled spaces below the skin. They are also found in surrounding layers lining the gut, lungs, and urinary systems, as well as around blood vessels and the fascia between the muscles. A 3-D latticework of collagen and connective tissue, the interstitium is a highway of moving fluid. This new organ is understood to be a conduit for fluids to enter the lymphatic system, which could lead to an understanding of how diseases are spread throughout our body. Researchers found that the interstitium accounts for 20 percent of the body, and if it is an organ, it is the largest organ we have, even larger than the skin.

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