Phosphorus

The term “phosphorus” was originally used to describe any physical substance which after some exposure to light would glow when put in darkness. Now, “Phosphorus” is the name given to the chemical element with atomic number 15, symbol P, and atomic weight of 30.97. Historical accounts have it that a certain Hennig Brand first prepared Phosphorus in the year 1669 by the process of destructive distillation of urine.

The focus of this essay is to briefly discuss the medical importance of this element.

 

The natural distribution of Phosphorus

Phosphorus does not occur in nature as the pure elemental substance, but combined with oxygen as the phosphate ion (PO₄^3-) it is widely distributed throughout the lithosphere, hydrosphere and biosphere of our planet Earth. This is to say that as the phosphate ion Phosphorus is universally distributed throughout the earth crust and its mineral resources, the oceans and waterbodies, and all the living organisms of this planet. As a monument to the great importance of Phosphorus to the life courses on Earth nature intervened with the phosphorus cycle, a complex network of geological processes which are constantly in operation to recycle the phosphate ion through these three spheres of life on our planet.

In the lithosphere Phosphorus occurs as deposits of calcium phosphate minerals, otherwise known as phosphate rocks. These mineral deposits are predominantly insoluble in water and hence immobile. The natural process of weathering breaks down these rocks to very fine particles in the passage of time, upon which rainwater subsequently acts, dissolves, releases and carries the phosphate ion in the running stream. This latter process is termed leaching. The fate of the phosphate ion formed depends much on its destination. It may be absorbed with groundwater and utilized as an essential nutrient by plants, and also by lower living species that can utilize phosphate ion as a source of Phosphorus. Humans and animals cannot utilize the phosphate ion directly but otherwise obtain their supply of Phosphorus by consuming plants mainly. This describes a bird’s-eye view of the movement of Phosphorus from the lithosphere to the biosphere. The death and consequent decomposition of living organisms represents a reverse process which returns phosphate ions from the biosphere to the lithosphere.

The phosphate ion carried in running water may end up in the waterbodies, and there combine with mostly calcium ions, but also with aluminum and iron to some extent, and then precipitate as insoluble mineral species.

The following discussion of how Phosphorus occurs in humans typically reflects the occurrence of this element in all of the biosphere.

 

The occurrence of Phosphorus in humans

I open this section with the following quotation from Mellor’s Treatises: “Phosphorus was on the earth in gaseous, liquid, or solid form before the dawn of life, and since then, all animal and vegetable creations have combined with the physical forces always at work in inanimate nature to distribute and redistribute the phosphorus, to divide it up, and carry it from place to place. If the biography of atoms could be written, the chapters on phosphorus would be the most interesting and the most varied. --- WBM Davidson, 1893”.

Human life depends on Phosphorus for its existence and it is inconceivable if any other chemical element could match it in importance in this regard. Phosphorus occupies the core of both the tissues (structure) of humans and the metabolic processes (function) that occur therein, as exemplified by the discussions below.

BONE. The bones impart shape to the human body, make movement possible, and provide protective housing for marrow which is the organ within which blood is made. Bone tissue is made up of a network of collagen protein fibres, strengthened with a derivative compound of Phosphorus known as hydroxylapatite. In terms of bulk this hydroxylapatite constitutes more than half the mass of the hard bone tissue, and imparts mechanical strength to the bone. The hydroxylapatite of bone is a variant of the compound calcium phosphate Ca₃(PO₄)₂ wherein Phosphorus is combined with calcium and oxygen, this basic material is hydrated with water molecules, and there is trace amounts of other ions such as magnesium, fluoride, chloride and carbonate. It is not known why nature chose Phosphorus above every other element as the core of this important bone tissue, and what substitution of Phosphorus with any other element means for the structural integrity of bone tissue, but what has been said already is the natural state of affairs. It is what it is, and it can be said again that Phosphorus is an essential element for the formation of bone tissue.

TEETH. Human teeth is a bony structure and what has been said above about the importance of Phosphorus to the structural makeup of bones holds true to a very large extent. Phosphorus is also at the core of the structure and strength of human tooth enamel.

CELL MEMBRANE. The main building blocks of the cell membrane of every living cell are phospholipids, four kinds of which are known to occur naturally in humans namely phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine and phosphatidylinositol. In a typical cell membrane these chemical substances are arranged in a mosaic pattern of double layer encasing the cellular subunits to form a separate entity, an arrangement which makes the cell membrane fluid in structure and also imparts on the cell adaptive characteristics to survive in the aquatic environment prevalent within human tissues. All four of these phospholipids are in chemical nature compounds of Phosphorus, in which this essential element as the phosphate intermediate is chemically combined with a glycerol backbone, fatty acid side chains and either of choline, ethanolamine, serine or inositol. Again, why the natural order settled for Phosphorus above every other element in the making of this critical cellular substructure cannot be told with certainty but the phospholipids present yet another testimony of how essential our chemical element is to life.

NERVOUS TISSUE. Regular phospholipids and a type of it known as sphingomyelins form the basic fabric of the nervous tissues of humans, of which the proportion of sphingomyelins in both the central and the peripheral nervous system is currently thought to supersede all other tissues of the body. The element Phosphorus is again deeply embedded in the structures of both of these chemical substances.

DNA. The storage molecule for genetic information in cells, deoxyribonucleic acid (DNA), will be in the form of a very long ladder if it could be straightened out. The rungs on this ladder will be pairings of the purine bases with pyrimidines, namely adenine with thymine and guanine with cytosine, in loose chemical bonding that could be likened to two human beings with an arm each joined palm-to-palm over a large gulley whilst the other arm of each person is wrapped tightly round a firmly fixed stake on either side of this gulley. The ease of breaking this chemical union is just as simple as each person letting go of the arm of the other person. The rail on either side of this ladder which serves as backbone for the purine and pyrimidine bases is made up of a small sugar molecule known as deoxyribose and the element Phosphorus, as its phosphate derivative. Deoxyribose is strongly joined with phosphate (a derivative of Phosphorus) in covalent bonding in an alternating arrangement to form the backbone of the DNA molecule on both sides. Thus is the critical role of the element Phosphorus in the genetic material of cells.

RNA. Ribonucleic acids (RNAs) are usually copied out of definite segments along the DNA strands and encode the genetic information for the synthesis of specific functional and structural proteins within cells. One key difference between DNA and RNA is that the latter is a single strand, very much like what is formed after cutting a ladder apart along its long axis. Moreover the RNA molecule is much shorter in length compared to DNA. Otherwise, phosphate (a derivative of the element Phosphorus) is covalently bonded to ribose (a derivative of deoxyribose in DNA) in alternating arrangement, with one kind of purine base or pyrimidine bonded directly to each ribose unit depending on the gene(s) encoded. Thus, RNAs are again another form in which the element Phosphorus occurs in humans.

ATP. Biochemists colloquially refer to adenosine triphosphate (ATP) as the “energy currency” within living organisms. The myriad of daily life activities which every human being is involved with, and all the metabolic processes occurring in humans, are all possible because of ATP. Just as money ATP is simply exchanged between the biological systems and metabolic processes; ATP is recycled by being consumed in anabolic (synthetic) metabolic processes and regenerated through catabolic (breakdown) processes. Structurally, the ATP molecule is made up of adenine, ribose and three molecules of phosphate (a derivative of the element Phosphorus) in such an arrangement that the first two components are bonded in one arm whilst the phosphate fragments are bonded one to another as in a chain in a separate arm of the ribose unit. Cleavage of the phosphate bonds of ATP releases energy, and their formation is a mechanism for entrapment and storage of chemical energy in biological systems. We again see our element Phosphorus in ATP molecules.

PHOSPHORYLATION. Almost all enzymes, B-complex vitamins and most other functional proteins in the body are activated through a process known as phosphorylation. These biological components are otherwise inactive and as such useless to the body; by means of the mechanism of phosphorylation these vital principles are kicked to action. The process of phosphorylation simply is the bonding of a phosphate (a derivative of the element Phosphorus) group to the inactive principle, which instantaneously imparts activity to the component involved. The source of phosphate for the purpose of phosphorylation is varied but is mostly obtained from ATP. Our interest here in this vital process of life is the involvement of the element Phosphorus, which is presented as its derivative phosphate.

 

Significance of Phosphorus in human disease

The reader should appreciate by now that very scientific and rational considerations underlie the attempt of this author to relate the element Phosphorus to human disease. The supply of Phosphorus to a human being is dynamic, this element predominantly obtained as organic phosphate compounds in the diet. Depending on the richness of diet in terms of these phosphate compounds, however, the supply of Phosphorus to the human consumer could be more or less inadequate. Insufficient consumption of phosphate derivatives as nutrients in diet over a long period of time will lead to Phosphorus (or phosphate) deficiency, with deleterious consequences on multiple organ systems of the human body.

The fact that Phosphorus exits in the human body in a dynamic equilibrium and what that means as a contributory factor to human disease has evaded popular attention. In pursuance of an orientation to such an idea the following quotation is made verbatim from Mellor’s Treatises: “The waste of muscular and nervous tissue involves a decomposition of the phosphorus compounds. The products of decomposition are carried by the blood to the kidneys, and there excreted with the urine chiefly as sodium ammonium phosphate. There seems to be a relation between the amount of phosphorus compounds discharged from the system, and the activity of the brain, and this led to the inference that phosphorus is a metabolic product of the activity of the brain, and that phosphate foods are needed for brain workers. The idea has crystallized in the well-worn phrase ‘ohne Phosphor kein Gedanke’, without phosphorus no thought. A normal adult excretes the equivalent of 3 to 4g of phosphoric acid per diem. Part of this is derived from the food, and part from muscular waste”.

The physiological state during which the levels of Phosphorus in the human body is consistently lower than what is needed to support metabolism is referred to as hypophosphataemia. According to a factsheet recently published by the National Institutes of Health (NIH, USA) the effects of hypophosphataemia on health can include anorexia, anaemia, proximal muscle weakness, skeletal diseases (bone pain, rickets, osteomalacia), increased infection risks, paraesthesias, ataxia, and confusion. In the opinion of this author hypophosphataemia results to degeneration and failure of multiple organ systems of the human body, and is a major underlying cause for ailments including asthenia, muscular weakness, chronic fatigue syndrome, neuropathy, and osteoporosis.

 

Supplementation of Phosphorus

The author affirms that medical treatments for the ailments namely asthenia, chronic fatigue syndrome, peripheral neuropathies, and osteoporosis should always be supported with supplementation of Phosphorus. However, the Phosphorus in its pure elemental form is extremely poisonous and cannot be taken. Calcium phosphate may be safely used for this purpose, from which after digestion Phosphorus is absorbed as phosphoric acid into the bloodstream for further processing. Although calcium phosphate falls short of the ideal as a source of Phosphorus by reason of its high content of calcium ions, with evidence emerging to increasingly implicate calcium ion in the causation of some cardiovascular diseases.

The soluble alkali metal salts of phosphate should also be avoided as a source of Phosphorus. Among this group are sodium triphosphate, sodium hydrogen phosphate, sodium dihydrogen phosphate, and their potassium counterparts. These salts are not safe for internal consumption as they are associated with much greater risk for precipitating insoluble stones in body tissues and the kidneys.

The ideal form of Phosphorus for supplementation is phosphoric acid (H₃PO₄). The latter is water-soluble and readily absorbed from the intestines into the bloodstream. Once absorbed phosphoric acid is fed directly into the body’s metabolic processes wherein the phosphate ion is required. The big note of caution here is that by phosphoric acid is meant a finished pharmaceutical preparation including phosphoric acid as a major active ingredient. The phosphoric acid of commerce is a very pure and strong acid which can easily destroy the tissues of the body. The layman should have nothing to do with this form of phosphoric acid, and at best, should never keep stock of it at home. Reference is here made to phosphoric acid which has been professionally diluted by a pharmacist or prepared ready to consume as a finished pharmaceutical product. These forms are usually given with specific instructions for further dilution so that the consumer is guided to safely administer them.

 

References:

·        JW Mellor (1947). A comprehensive treatise on inorganic and theoretical chemistry, vol. 8, pp 732, 737. Longman, Green and Co.

·        NIH (USA). Phosphorus – Fact Sheet for health professionals. Online resource accessed at https://ods.od.nih.gov/factsheets/Phosphorus-HealthProfessional/#en1. Date: Friday, 25 August 2023.