Distribution, processing and storage of magnesium ions in the human body:

In a human body weighing 70 kg there is about 24 g of magnesium (this value varies from 20 g to 35 g, depending on the source). About 60% of this amount is in bone, 29% in muscle, 10% in other soft tissues and only 1% in intracellular fluids. In the organisms of the elderly (over 60 years), the content of magnesium is reduced to 60-80% of the content in the tissues of children.
The highest magnesium content includes tissues with the highest intensity of metabolism processes, such as the brain, muscles (about 9.5 mmol / kg), heart (about 16.5 mmol / kg), liver and, unfortunately, also cancer tissue (about 8 mmol / kg) . Erythrocytes contain three times more magnesium (2.4-2.9 mmol / L) than plasma (0.8-1.6 mmol / L). Most magnesium-dependent physiological processes are determined by the presence of the ionized form of the element intracellularly.
Due to the high homeostatic properties of plasma, magnesium and other elements are present in it at a constant concentration, they are also associated with plasma proteins and other chemical compounds which determines their level, so the determination of magnesium levels in plasma is very unreliable. Medical conditions in the human body have little effect on the levels of elements in plasma, while they greatly disrupt the homeostasis of intracellularly ionized elements.

Absorption of magnesium ions occurs mainly in the jejunum and ileum where the acidic environment prevails. Absorption occurs in two stages:
• by passive transport, based on the phenomenon of electrochemical gradient;
• diffusion facilitated by the TRPM6 carrier protein (transient receptor potential melastatin) located in intestinal epithelial cells.
Magnesium absorption is parallel to water absorption. This process is more efficient when its duration is longer. The degree of absorption is directly dependent on the degree of element ionization, diet balance and hormonal homeostasis. Magnesium absorption is faster in an acidic environment, with a diet rich in animal proteins, unsaturated fats, vitamin B6, sodium, lactose, vitamin D, with proper secretion of insulin and parathyroid hormone into the blood. In turn, magnesium absorption is inhibited by: alkalization of the environment, some proteins, some fats, saturated fatty acids forming insoluble compounds with magnesium, food fibers, phytic acid contained in cereals, oxalic acid found in many plants (rhubarb, spinach, sorrel), excess calcium (hence the simultaneous dairy products), alcohol, fluorides and phosphates. It should be remembered that some drugs also inhibit the absorption of magnesium.
Magnesium is generally an element that is difficult to absorb. It has been calculated that only about 30% of magnesium consumed by humans is absorbed daily (of which 10% in the mechanism of passive diffusion). The rest remain expelled in various ways. All kinds of intestinal diseases from proliferative to autoimmune have a direct impact on this process.
The stability of magnesium levels in tissues determines not only efficient and undisturbed intestinal absorption, but also the correct reabsorption of the element in the ascending part of the nephron.

Magnesium is an mainly intracellular ion. More than half of magnesium is found in bones, about a quarter is in the muscles, and about a quarter is distributed throughout the body, mainly in the nervous system and organs with high metabolic activity, such as the liver, digestive tract, kidneys, endocrine glands. The magnesium reserve is probably located primarily in the bones.
At present, however, we have little knowledge about the mechanisms of transporting magnesium into the cell and maintaining an increased concentration of this element intracellularly. However, we know that magnesium absorption is largely due to facilitated diffusion and depends on many metabolic and hormonal processes of the body.
It is known that vitamins B6 and D as well as insulin are able to increase the content of intracellular magnesium, where adrenaline or cortisol work quite the opposite.
Excretion
The main organ that eliminates magnesium from our body are the kidneys. Small amounts of this element are also excreted through the intestines and also with sweat. The kidneys are responsible for the proper concentration of magnesium in the extracellular space.
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