This is the second part in a three part guest article series by Brandon Brown, student at National College of Natural Medicine and Chinese medicine blogger. You can access the first part of the article which covers salt in the macrocosm – nature. I should note that he has posted references for the entire series on his blog, you can access those references by clicking on this link. -Eric
Salt in the Microcosm
By preserving meat with salt, mankind was unknowingly creating a vicious cycle that would change the health of all people up to the present day. It is estimated that before the advent of this preservation technique people consumed no more than 0.5 grams of naturally occurring salt per day (g/d). After brining was put to use, daily consumption jumped to an estimated 10 g/d (because even though the meat is soaked in water to reconstitute it, no amount of soaking can remove a large amount of salt). This continued to climb throughout the centuries, upwards to nearly 18g/d (some estimates in Scandinavia indicate consumption near 100g/d) until the advent of refrigeration techniques which brought estimated consumption back down to its present day levels of 10 g/d. It is hypothesized that one reason for the stabilization at 10g/d instead of 0.5g/d is the addictive nature of salt: in the presence of continued salt loads the taste receptors on the tongue down-regulate their sensitivity to the salty flavor. However, as we will see, salt plays a crucial role in the nervous system, and it could be this current cultural bias for all things cerebral that creates our hunger for the briny crystal.
One of the most prolific cellular mechanisms in the body is the sodium-potassium pump. These pumps are found in a number of cells throughout the body, but most importantly in the nerve cells of the Central Nervous System. This mechanism, called Na+/K+-ATPase, regulates cellular chemistry and polarity by using ATP to remove 3 Na+ intracellular ions and replace them with 2 K+ ions. Na+/K+-ATPase is the mechanism that is responsible for the nerve’s ability to achieve the resting potential of approximately -70 mV by removing a net positive charge from the intracellular fluid with each pumping action. The creation of this potential primes the neuron to do work, in this case to release its charge as a rush of electrochemical ions, creating a signal that releases neurotransmitters at the terminal end of the neuron. The charging of this battery comes at a cost of a single phosphate group from ATP (converted to ADP). Because the pump is operating against the normal flow of the concentration gradient, energy is required to create this potential difference. This process is such that a large differential between sodium and potassium is created:
Table 1: Concentration of fluids by ion type (mmol/L)
| Ion | Extracellular | Intracellular |
| Na+ | 150 | 15 |
| Cl- | 110 | 7 |
| K+ | 5 | 150 |
Therefore the exterior of the cell is essentially salt water (NaCl), and the interior of the cell is largely dissolved potassium ions.
This is striking for a couple of reasons. First, in the resting state we see that salt water is kept on the outside of the membrane and only when an action or graded potential occurs is it allowed to rush into the cell. To reach the resting potential the cell must actively store potassium, and excrete sodium. In other words, the movement of salt (in this case sodium) into the cell causes the transmission of an electrochemical action potential. It is this action potential that is thought to give rise to all cognition and movement in the body. The axon, the long transmitting portion of the neuron, propagates the signal through voltage controlled sodium channels. The inward movement of salt is giving birth to movement and thought, whereas the expulsion of salt promotes stillness and thusly, stores great potential.
Secondly, the regular and crystalline lattice structure is perhaps more than metaphorical. In cognitive neuroscience, most theories of the mind involve describing the geometrical structure of the neural lattice as an explanation of functional capabilities. For example, the visual cortex is organized in columnar functional groups that serve to detect edges in the visual field. The creation of memory involves creating a new pathway on an already established lattice. Therefore, as sodium enters the cell it gives its organizational properties over to the cell to provide for the creation of new synaptic connections and lattice-like structures. The lattice-like structure of the salt is reflected in the lattice-like structure of the brain.
Figure 2: Columnar structure of neurons in the visual cortex and the octahedral geometry of sodium chloride
In terms of SSH research, it seems that excess dietary salt may not only change the sodium levels in the plasma but also in the cerebrospinal fluid, inhibiting Na+-K+-ATPase in both locations, perhaps giving rise to cognitive changes (Khalil 2005).
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In the next and last installment of this series, Brandon discusses salt from the perspective of Classical Chinese texts and brings the various ideas together. Please look forward to it tomorrow. -Eric
Tags: crystal, Science, microcosm, human physiology, organization, water, nature, salt
