Phosphorus: Energy Reserve
Phosphorus (P)
For humans – an energy reserve.
On the role of phosphorus in the vital processes of the human body, the well-known biologist and biochemist V.A. Engelhardt said very well: “Without phosphorus, there is no movement, for the chemistry of muscle contractions is entirely the chemistry of phosphorus compounds.”
Phosphorus is a component of proteins, fats, nucleic acids, activates mental and physical activity, and provides the human body with energy.
The daily requirement of the human body for phosphorus is 800 mg. The average daily intake of phosphorus is approximately 1500 mg for men and 1000 mg for women. During intense physical training, the need for phosphorus can be significantly increased.
Approximately 60–70% of phosphorus is absorbed from a regular mixed diet. It has been shown that phosphorus absorption ranges from 4 to 30 mg/kg of body weight per day and is related to its intake. The efficiency of phosphorus absorption largely depends on the calcium content in the diet. Phosphorus works in conjunction with calcium, and their ratio should be maintained at 1:1 in equivalents (1:1.5 by weight).
The total phosphorus content in the human body is about 500 g in men and 400 g in women.
Physiological states characterized by an increased need for phosphorus (growth, pregnancy, breastfeeding) are accompanied by a corresponding increase in absorption. In older age groups, changes occur in phosphorus excretion and adaptation to dietary phosphorus. It has been shown that despite consuming the recommended phosphorus intake, a negative balance is observed in individuals over 65 years of age due to phosphorus loss in urine.
Phosphorus in extracellular fluids constitutes only 1% of the total phosphorus in the body. The majority (70%) of total phosphorus in plasma is found as a component of organic phospholipids. However, the clinically useful fraction in plasma is inorganic phosphorus, 10% of which is bound to protein, 5% consists of complexes with calcium or magnesium, and the majority of inorganic phosphorus in plasma is represented by two fractions of orthophosphate.
Phosphorus is found in all cells of the body. The main sites containing it are hydroxyapatite in bone and skeletal muscle (human bones consist of hydroxyapatite, which is a complex salt and participates in protein metabolism).
The cellular and molecular mechanism of phosphorus absorption in the intestine is not fully understood. The transport of phosphorus across the intestinal cell is an active, sodium-dependent pathway. Intracellular levels of phosphorus are relatively high. Parathyroid hormone does not directly regulate phosphorus absorption in the intestine.
The cellular and molecular mechanism of phosphorus absorption in the intestine is not fully understood. The transport of phosphorus across the intestinal cell is an active, sodium-dependent pathway. Intracellular levels of phosphorus are relatively high. Parathyroid hormone does not directly regulate phosphorus absorption in the intestine.
The administration of the active metabolite of vitamin D leads to an increase in phosphorus absorption in both healthy individuals and patients with uremia. Regulation of the overall phosphorus level in the body requires coordinated efforts of the kidneys and intestines. Under conditions of low phosphorus intake from food, the intestine increases its absorption, while the kidney enhances renal transport to minimize losses in urine. This adaptation is ensured by changes in the levels of the active metabolite of vitamin D and parathyroid hormone in plasma. If adaptive measures are unable to compensate for low phosphorus intake, then bone phosphorus may be redistributed to soft tissues. However, these compensatory capabilities are not limitless.
Fecal losses of phosphorus range from 0.9 to 4 mg/kg per day. The main excretion occurs through the kidneys over a wide range (0.1–20%). Thus, the kidneys have the ability to effectively regulate plasma phosphorus. The rate of renal reabsorption is regulated by the concentration of phosphorus in plasma. The hormonal regulator of renal phosphorus reabsorption is parathyroid hormone and nephrogenic cAMP. The concentration of parathyroid hormone in plasma positively correlates with the level of phosphorus excretion in urine. The main signs of phosphorus loss in urine are increased phosphorus absorption and elevated levels in plasma. Conditions that lead to hyperphosphaturia include hyperparathyroidism, acute respiratory or metabolic acidosis, diuretics, and increased extracellular phosphorus mass. Decreased phosphorus excretion in urine is associated with dietary phosphorus restriction, increased plasma insulin, thyroid hormones, growth hormone, or glucagon, alkalosis, hypokalemia, and decreased extracellular phosphorus concentration.
Fecal losses of phosphorus range from 0.9 to 4 mg/kg per day. The main excretion occurs through the kidneys over a wide range (0.1–20%). Thus, the kidneys have the ability to effectively regulate plasma phosphorus. The rate of renal reabsorption is regulated by the concentration of phosphorus in plasma. The hormonal regulator of renal phosphorus reabsorption is parathyroid hormone and nephrogenic cAMP. The concentration of parathyroid hormone in plasma positively correlates with the level of phosphorus excretion in urine. The main signs of phosphorus loss in urine are increased phosphorus absorption and elevated levels in plasma. Conditions that lead to hyperphosphaturia include hyperparathyroidism, acute respiratory or metabolic acidosis, diuretics, and increased extracellular phosphorus mass. Decreased phosphorus excretion in urine is associated with dietary phosphorus restriction, increased plasma insulin, thyroid hormones, growth hormone, or glucagon, alkalosis, hypokalemia, and decreased extracellular phosphorus concentration.
Biological role in the human body. Phosphorus plays a major role in the organs and tissues of humans in the form of its compounds, with phosphoric acid playing a leading role. It is involved in the construction of numerous enzymes, necessary for fat metabolism, for the synthesis of carbohydrates and their breakdown. The brain tissue and the bone tissue of the skeleton consist of phosphoric salts.
Inorganic phosphorus performs structural functions: it is part of the phospholipids of cell membrane structures; it is a component of the buffer system of blood and other biological fluids, providing support for acid-base balance.
Phosphorus in the form of salts and phosphoric acid is present in both muscle and bone tissues. It contributes to the development of the skeleton, increases the resistance of teeth to caries, is necessary for the functioning of the central nervous system, and participates in intracellular metabolism.
Phosphorus in the form of phosphates is part of nucleic acids and nucleotides (DNA, RNA), participates in the processes of coding and storing genetic information. Phosphorus compounds are involved in essential energy metabolism processes. Adenosine triphosphate (ATP) and creatine phosphate are energy reservoirs, and their transformations are associated with thinking and mental activity, energy supply for the body.
Phosphorus compounds participate in enzymatic processes, ensuring the manifestation of biochemical functions of several vitamins, regulation of metabolic processes (via cAMP), conduction of nerve impulses, and muscle contraction.
Inorganic phosphorus performs structural functions: it is part of the phospholipids of cell membrane structures; it is a component of the buffer system of blood and other biological fluids, providing support for acid-base balance.
Phosphorus in the form of salts and phosphoric acid is present in both muscle and bone tissues. It contributes to the development of the skeleton, increases the resistance of teeth to caries, is necessary for the functioning of the central nervous system, and participates in intracellular metabolism.
Phosphorus in the form of phosphates is part of nucleic acids and nucleotides (DNA, RNA), participates in the processes of coding and storing genetic information. Phosphorus compounds are involved in essential energy metabolism processes. Adenosine triphosphate (ATP) and creatine phosphate are energy reservoirs, and their transformations are associated with thinking and mental activity, energy supply for the body.
Phosphorus compounds participate in enzymatic processes, ensuring the manifestation of biochemical functions of several vitamins, regulation of metabolic processes (via cAMP), conduction of nerve impulses, and muscle contraction.
Synergists and antagonists of phosphorus. The absorption of phosphorus in the human body is enhanced by vitamins A, D, F, as well as potassium, calcium, iron, manganese, hydrochloric acid (gastric juice), enzymes, and proteins.
At the same time, aluminum, iron, magnesium, calcium, along with excessive sugar consumption, as well as vitamin D, parathyroid hormone, estrogens, androgens, corticosteroids, and thyroxine can lower phosphorus levels in the body.
At the same time, aluminum, iron, magnesium, calcium, along with excessive sugar consumption, as well as vitamin D, parathyroid hormone, estrogens, androgens, corticosteroids, and thyroxine can lower phosphorus levels in the body.
Signs of deficiency. Phosphorus deficiency can cause anxiety, irritability, weakness, tremors, bone pain, rickets, periodontitis, fatigue, irregular breathing, numbness, increased skin sensitivity, and changes in weight.
With excess phosphorus in the body, the levels of manganese and calcium significantly decrease, which can contribute to the development of osteoporosis. Excessive phosphorus intake also provokes the development of urolithiasis.
Phosphorus is necessary: in fractures, osteoporosis, caries, and nervous disorders.
Food sources of phosphorus: brewer’s yeast, dairy products, eggs, meat, fish, seaweed, dried fruits: raisins, dried figs, prunes; fruits: viburnum, apples (0.5–3%); cereals and legumes: beans, peas, buckwheat, corn, oats, millet, soft wheat, hard wheat, long-grain white rice, short-grain white rice, unrefined rice, wild rice, rye, soybeans, beans, lentils, barley; whole grains, bran; vegetables: celery, asparagus, Jerusalem artichoke, horseradish, garlic; greens: parsley greens, celery greens, garlic greens, sorrel; nuts and seeds: peanuts, cashews, sesame, poppy, macadamia, almonds, Brazil nuts, walnuts, pine nuts, sunflower seeds, pumpkin seeds, pistachios, hazelnuts; mushrooms: porcini (white mushrooms), oyster mushrooms.
Food sources that are high in protein (meat, milk, eggs, and grains) also have a high phosphorus content. The relative contribution of major food groups to total phosphorus intake is approximately as follows: 60% from milk, meat, poultry, fish, and eggs; 20% from cereals and legumes; 10% from fruits and juices. Alcoholic beverages on average provide 4% of the phosphorus consumed, while other drinks (coffee, tea, soft drinks) account for 3%.
Dairy products, particularly cheeses (up to 600 mg/100 g), and eggs (in the yolk – 470 mg/100 g) are significantly high in phosphorus. There is a high phosphorus content in legumes (in beans – 480 mg/100 g, peas – 369 mg/100 g), in bread and cereals (200–300 mg per 100 g), but the bioavailability of phosphorus from grain products is low due to the high proportion of phytic compounds. Meat and fish are important sources of phosphorus (120–140 mg/100 g).