Salt Sensitive Hypertension and Classical Chinese Medicine, Part 3

This is the final post in a three part series by Brandon Brown, blogger and student of Classical Chinese Medicine at NCNM.  You can read the first two parts here and here, and can read references for the article by visiting Brandon’s site here.

Salt in the Classics

Salt is mentioned a number of times in the classics. In the Neijing Suwen, salt is considered the flavor of the Kidney. But what does this mean exactly? What follows are the most descriptive and instructive references from the Suwen followed by my translations.

Chapter 67
北方生寒，寒生水，水生鹹，鹹生腎，腎生骨髓，髓生肝。其在天為寒，在地為水，在體為骨，在氣為堅，在藏為腎，其性為凜，其德為寒，其用為，其色為黑，其化為肅，其蟲鱗，其政為靜，其令，其變凝冽，其眚冰雹，其味為鹹，其志為恐。恐傷腎，思勝恐，寒傷血，燥勝寒，鹹傷血，甘勝鹹。

“The north generates cold, cold generates water, water generates salty, salty generates kidneys, kidney generates the marrow, marrow generates the liver. In heaven it is cold, on earth it is water, in the body it is bone, its qi is hard, in the Zang it is the Kidney, its nature is cold(shivering), its virtue is cold, it is “use”, its color is black, it changes into solemn-ness(seriousness), it is worms and fish-scales, its government is stillness(jing), it causes, its pathological change is congealing coldness, its natural disaster is ice hail, its flavor is salty, it is will by fear. Fear impairs the kidney, thought defeats fear, cold damages blood, dryness defeats cold, salty damages blood, sweet defeats salty.”

Chapter 3
味過於鹹，大骨氣勞，短肌，心氣抑。
Excess salty flavor, causes great hardening of bone Qi, shortens the muscles, and restrains heart Qi.

Chapter 5
鹹勝苦。
Salty defeats bitter.

Chapter 10
是故多食鹹則脈凝泣而變色 。
Therefore, much eating of salty makes the pulse concrete and the color changing.

Chapter 22
心欲耎，急食鹹以耎之，用鹹補之，甘寫之。
The Heart desires softness, anxious people eat salty that softens it, use salty to mend it, sweet drains it.

—-

These excerpts from the Suwen indicate the myriad functions of salt. In Chinese Medicine, the Salty flavor is typically used to soften nodules as mentioned in Chapter 22, but we also see in Chapter 3, 10, and 67 that salt can pathologically also create hardness of Bone Qi, restrain Heart Qi, damage blood, and cause the pulse to be very firm. We can read these lines in typical Chinese Medicine fashion: that as a remedy, the salty flavor has a purpose in softening nodules, in moderation salt perhaps allows the Kidney to perform its function of storing, but pathological excess consumption of salt can lead to sclerosis.

In Chinese Medicine, the 5 flavors that go with the 5 organs typically counteract the nature of the targeted organ. For example, the energetic nature of the Liver is up and out whereas the flavor Sour astringes and contracts. The Heart, the fire organ, is up and bitter is down. For the Lung, its nature is contracting down and in, whereas pungent is the opposite: up and out. For the Kidney, as we see in Chapter 67 above, the energetic nature is definitely to store by freezing. Salt, must counteract this freezing nature, as we know that it does from our experience: salt both reduces the freezing point of water and raises the boiling point. The presence of salt liquefies ice, and thus can soften hardness (tumors, goiter, etc.). But because salt has an affinity with the Kidney it counteracts the storing nature of the organ, liquefying the Kidney energy (perhaps Jing) to be used in the body as Qi. Therefore we see again that, salt pushes out from the inside.

In their paper on the Classical Energetics of the Five Flavors (find in references section), Arnaud Versluys and Jessica Atkins describe the therapeutic actions of the five flavors in terms of tonification and purgation. In cases of excess or deficiency, the organs can be respectively purged or tonified with the appropriate flavor as shown in the figure below.

Figure 2: The actions of the 5 flavors

Organ:  Excess of, purge with : Deficiency of, tonify with
Fire :  Sweet : Salty
Earth : Bitter : Sweet
Metal : Pungent : Sour
Water :  Salty :  Bitter
Wood :  Sour :  Pungent

According to their interpretation, the salty flavor purges excess in the Kidneys and tonifies the Heart. In the case of SSH, chronic overexposure to dietary salt may act medicinally and impair or purge the storing function of the Kidney and thus over-tonify the Heart. Because the Kidney is also said to store pre-natal essence if there is no pathological influence to expel in the Kidneys, it is possible that what is purged is actually pre-natal essence (Jing). This essence is circulated throughout the body, transformed to Qi by the Liver function, and transformed and stored as Shen by the Heart. Shen, and thus consciousness, have as a substrate the brain, but Shen is housed in the Heart.

Therefore, the use of salt habitually may increase the Jing-Qi-Shen generation cycle, which makes us sharp and awake, but has the detrimental effect of possibly depleting pre-natal essence if the Kidneys are not constantly tonified. In the Suwen it mentions that at 8 times 7 years (56 years old), the hair (ruled by the Kidney) turns gray and the signs of aging begin to become visible. “The kidneys’ ability to excrete sodium declines gradually with age. If, with age, salt consumption is not reduced, sodium balance is maintained by raising fractional sodium excretion, which requires elevation of BP” (Khalil 2005). The accumulation of salt in the ocean over the years has begun to take its toll.

Because purgation of the Kidney in a non-pathological condition also tonifies the Heart, an interesting consequence of excess in the Fire element is that it easily overflows onto its child organ, the Earth. This would lead the Earth to become overwhelmed and thereby inhibiting it to control the Water element, whose function is diminishing due to the natural processes of aging. In CM, we say that the “Earth rules the muscles” and in the SSH case this clearly relates to the smooth muscle of the vasculature losing its ability to contract. Due to an excess in the Heart domain, the smooth muscle becomes dry, stiff, and brittle. The patho-mechanism of this is illustrated below.

The standard American diet is predominantly made of the flavors salty and sweet. The overwhelming absence of bitter (with the exception of Shen disturbing coffee and beer) and the overwhelming abundance of salt and sugar in the standard American diet may explain the danger of increased exposure to dietary salt.

Conclusion

It is not surprising that decreasing daily dietary salt intake will help in treatment SSH. However, what we learn from the classics and the physiology of salt in the body is that Kidney tonification is essential for SSH.

Because the Earth element has become so affected by this chronic exposure to salt, purging the Earth of excess with the bitter flavor will be important. Like a lone neuron in the brain, salt consumption is entangled in the higher social structures that predominate our times: working long hours, using the mind instead of physical labor for generating a living, exposure to a barrage of psycho-sensory information in terms of television, music, and people, along with increasing anxieties about all of it. Seen in this context it really is no wonder why SSH is a modern disease of the “developed” world.

Brandon Brown

Related articles

• Salt-sensitive hypertension and Classical Chinese Medicine, Part 1 (7)
• 7 keys to understanding the Classical Chinese Medicine concept of organs (4)
• Classical Chinese medical symbolism: Wood, Metal and Spring (part 2 of 2) (18)