Phosphorus is widely distributed in the biosphere, with crust content in the top ten and seawater concentration in the second category. It widely exists in animal and plant tissues, and it is also one of the most abundant elements in human body, ranking sixth after calcium. Phosphorus exists in all cells of human body, accounting for about 1% of human body weight. It is necessary for maintaining bones and teeth and participates in almost all physiological and chemical reactions. Adults contain about 600-900g of phosphorus, 85.7% of which is concentrated in bones and teeth, and the rest is dispersed in all tissues and body fluids, half of which is in muscle tissues. It not only constitutes the human body composition, but also participates in the very important metabolic process in life activities, and is a very important element of the body.
Phosphorus in human body: Phosphorus is an important component of human genetic material nucleic acid, and also an important component of adenosine triphosphate (ATP), the key substance of human energy conversion. Phosphorus is also a component of many enzymes. Biofilm phospholipids are important components of bones and teeth and play a very important role in human life activities. Phosphorus is also an important substance to make the heart beat regularly, maintain the normal function of the kidney and transmit nerve stimulation. Without phosphorus, nicotinic acid (also known as vitamin B3) cannot be absorbed; The normal function of phosphorus needs vitamin (vitamin food) D and calcium (calcium food) to maintain.
triphosadenine
Phosphorus in plasma: about 2.5 liters of plasma possessed by the general human body contains about 75 ~ 100 mg of phosphorus and 250 mg of calcium. Under normal circumstances, everyone excretes 1000 mg of phosphorus from urine every day and night. The ratio of calcium to phosphorus is of great significance to the digestion and absorption of food. When the ratio of calcium and phosphorus in food is 1:2 ~ 2: 1, it is most suitable for calcium and phosphorus absorption. Phosphorus participates in the regulation of acid-base balance and helps the metabolism of glucose, protein and fat.
Adults need to get 0.66 grams of calcium and 0.74 grams of phosphorus from food every day, and children need more than 1 gram of calcium and phosphorus every day during their development. The absorption of calcium and phosphorus directly affects the calcification of bones. Vitamin D can promote the absorption of calcium and phosphorus.
A person with a normal weight of 60kg has a total phosphorus content of about 600g, of which 85% (about 520g) is distributed in bones and teeth, and the rest 15% is distributed in soft tissues and body fluids. Different soft tissues have different phosphorus contents. The phosphorus content in brain tissue is relatively high, reaching 4.4g/kg, while that in muscle tissue is 1.0g/kg, and the average phosphorus content in each soft tissue is 2.0g/kg. Phosphorus in soft tissue mainly exists in the form of organophosphorus, phospholipid and nucleic acid. Phosphorus contained in bone tissue mainly exists in the form of inorganic phosphorus, that is, it forms bone salt with calcium. Plasma (serum) contains both organic phosphorus and inorganic phosphorus, and the ratio of them is about 2: 1. When bone is formed, 2g calcium needs 1g phosphorus, and when organic phosphorus is formed, 2g nitrogen needs 1g phosphorus.
Function and importance of phosphorus to human body
1. constitutes bones and teeth.
Its function, like calcium, constitutes the support of the body and undertakes the load-bearing function.
Bone health
2. Important substances that constitute life
Phosphorus is one of the most important elements in the body, because it is one of the components of ribonucleic acid and deoxyribonucleic acid in all cells, and it is indispensable for genetic metabolism, growth and development, energy supply and so on. Phosphorus is also an essential element for all cells of organisms, and it is necessary to maintain the integrity of cell membranes and play a role in cells. Phospholipid is the main lipid component on cell membrane, which is related to membrane permeability. Promote the decomposition of fats and fatty acids, and prevent the accumulation of excessive acid or alkali in blood. The role of phosphorus also affects the acid-base balance in plasma and cells, promotes the absorption of substances, stimulates the secretion of hormones, and is beneficial to nerve and mental activities. Phosphorus can stimulate nerves and muscles, and make the heart and muscles contract regularly. Phosphorus contributes to cell division, proliferation and protein synthesis, and transfers genetic characteristics from the previous generation to the next generation. Phosphorus ion is necessary for carbohydrate, lipid and protein metabolism. As a cofactor, it acts on a wide range of enzyme systems and also exists in high-energy phosphate compounds. Such as organic phosphate, ATP, creatine phosphate, etc. It has the function of storing and transmitting energy. In the process of bone development and maturity, the balance of calcium and phosphorus is helpful to the utilization of inorganic salts. Phosphate can regulate the metabolism of vitamin D and maintain the internal environment stability of calcium.
Absorption and excretion of phosphorus
The daily intake of phosphorus is about1-1.5g. Phosphorus is absorbed in small intestine, especially in duodenum, jejunum and ileum. Phosphorus absorption can be divided into two mechanisms: active absorption and passive absorption through diffusion. The metabolic process of phosphorus is similar to that of calcium, and the balance of phosphorus in the body depends on the exchange of phosphorus in the internal and external environment. The main way of phosphorus excretion is through the kidney. Phosphorus not absorbed by intestine is excreted from feces, accounting for about 30% of human daily phosphorus intake, and the remaining 70% is excreted in the form of soluble phosphate through kidney, and a small amount can also be excreted through sweat. The factors affecting phosphorus absorption are similar to calcium. The increase of acidity can make use of the absorption of phosphorus. The absorption form is mainly acid phosphate (BH2PO4), and the absorption rate can reach 70%. Ca2+, Mg2+, Al3+ and Fe3+ can combine with phosphate to form insoluble salts, so too much calcium in food will affect the absorption of phosphorus. When the blood routine of patients with severe kidney disease is too high, Al(OH)3 latex is often taken to reduce the absorption of phosphorus.
Phosphorus is excreted by the kidney and intestine, and the renal excretion accounts for 70% of the total excretion. The renal excretion of phosphorus is also regulated by parathyroid hormone and vitamin D. When renal function is poor, phosphorus excretion decreases and blood scale increases.
About blood scale, it usually refers to phosphorus in inorganic phosphate in plasma. The plasma inorganic phosphorus content of normal adults is 0.96-1.44 mmol/L (3.0-4.5 mg/DL), and that of children is1.28-2.24 mmol/L (4.0-7.0 mg/DL).
Phosphorus is one of the most important elements in the body, because it is one of the components of ribonucleic acid and deoxyribonucleic acid in all cells, and it is indispensable for genetic metabolism, growth and development, energy supply and so on. Phosphorus is also an essential element for all cells of organisms, and it is necessary to maintain the integrity of cell membranes and play a role in cells. Phospholipid is the main lipid component on cell membrane, which is related to membrane permeability. Promote the decomposition of fats and fatty acids, and prevent the accumulation of excessive acid or alkali in blood. The role of phosphorus also affects the acid-base balance in plasma and cells, promotes the absorption of substances, stimulates the secretion of hormones, and is beneficial to nerve and mental activities. Phosphorus can stimulate nerves and muscles, and make the heart and muscles contract regularly. Phosphorus contributes to cell division, proliferation and protein synthesis, and transfers genetic characteristics from the previous generation to the next generation. Phosphorus ion is necessary for carbohydrate, lipid and protein metabolism. As a cofactor, it acts on a wide range of enzyme systems and also exists in high-energy phosphate compounds. Such as organic phosphate, ATP, creatine phosphate, etc. It has the function of storing and transmitting energy. In the process of bone development and maturity, the balance of calcium and phosphorus is helpful to the utilization of inorganic salts. Phosphate can regulate the metabolism of vitamin D and maintain the internal environment stability of calcium.
Human body's demand for phosphorus
The demand of phosphorus refers to the physiological demand of maintaining proper nutrition and health of the body. In the past, due to the extensive and abundant phosphorus in food, there was little nutritional phosphorus deficiency caused by dietary reasons, so there was little research on phosphorus demand. There is no index to evaluate phosphorus deficiency, but it is related to calcium requirement, and the ratio of calcium to phosphorus is mainly considered. Now it is considered that the level of inorganic phosphorus in blood is an important index to determine and estimate the average phosphorus requirement. The recommended reference intake of various groups of people formulated by China Nutrition Society is as follows:
Infant: It is mainly calculated from the average phosphorus intake of breast milk. The appropriate intake (AI) for infants before half a year old is 150mg/ day. After half a year, because the intake of phosphorus increased with the complementary food, it was set at 300 mg/day.
Children: Based on the growth rate and absorption and excretion efficiency of phosphorus in bones and soft tissues, the "factor addition algorithm" is adopted. /kloc-The appropriate intake of phosphorus for children over 0/year old is 450mg/day, for children over 4 years old, 500mg/day, and for children over 7 years old, 700mg/day.
Adolescent development period: The appropriate phosphorus intake for adolescents over 1 1 000 mg/day is also determined by "factor addition algorithm".
Adults: Because the relationship between the level of inorganic phosphorus in adult blood and phosphorus intake is clear and definite, the suitable phosphorus intake for adults is calculated to be 700 mg/day.
Old people: The absorption rate and excretion rate of phosphorus have not changed with the increase of age, so the suitable intake of phosphorus for the elderly is set at 700 mg/day for adults.
Pregnant women: Due to the improvement of phosphorus absorption rate during pregnancy, the fetal growth needs can be met without additional phosphorus intake, so the suitable phosphorus intake for pregnant women is still set at 700 mg/day.
Nanny: Because there is no evidence that the phosphorus requirement increases during lactation, the suitable intake of phosphorus for nannies is set at 700 mg/day.
Phosphorus-rich food
Phosphorus is widely distributed in food. The cells of animal food and food food are rich in phosphorus, and animal milk also contains phosphorus, so phosphorus coexists with protein. Animals are rich in lean meat, eggs, milk, liver and kidney, and kelp, seaweed, sesame paste, peanuts, dried beans and nuts are also rich in phosphorus. The phosphorus in grain is phytic phosphorus, which is unprocessed and has low absorption and utilization rate.
Effects of excessive phosphorus on human body
When regulating phosphorus intake, if the phosphorus content in the body is too high, it will also be harmful to the body. But generally speaking, the problem of excessive phosphorus intake from diet is not easy to happen, and it will only happen under some special circumstances. For example, excessive use of phosphorus preparation in clinic is mainly harmful to hyperphosphatemia, which affects the absorption and utilization of calcium and has adverse effects on bones. However, sufficient calcium in the body can effectively prevent the adverse effects caused by high phosphorus.
The maximum tolerable intake (UL) of phosphorus proposed by China Nutrition Society is: children and pregnant women, 3000 mg/day; Teenagers, adults, the elderly and nursing mothers, 3500mg/ day.
In 2002, the nutrition and health survey report of China residents showed that the average daily phosphorus intake of urban and rural residents in China was 978.8 mg, which was higher than the appropriate intake, which was related to the dietary structure of plant food in China.
What are the symptoms and hazards of phosphorus deficiency?
Phosphorus deficiency can cause abnormal development of bones and teeth, osteoporosis, rickets, anorexia and other symptoms.
Almost all foods contain phosphorus, so human phosphorus deficiency is extremely rare. The intake of phosphorus is always higher than that of calcium, which is completely sufficient in most cases. However, phosphorus deficiency may occur if:
(1) Excessive intake of nonabsorbable antacids, such as aluminum, calcium and magnesium preparations, may affect the absorption of phosphorus;
(2) infants who have been fed milk for a long time;
(3) Vegetarians often eat a high-fiber diet produced in phosphorus-deficient soil.
Phosphorus-related deficiencies also include rickets, a childhood disease caused by phosphorus, calcium or vitamin D deficiency or calcium-phosphorus imbalance.
Osteomalacia is adult rickets, which is caused by long-term lack of phosphorus, calcium or vitamin D or imbalance of calcium and phosphorus. Of course, too much phosphorus intake can also cause harm to the body. Such as osteoporosis, fragility and tooth decay. Due to the close relationship between calcium and phosphorus in human body, various symptoms of calcium deficiency become more and more obvious, listless and even collapse, which destroys the balance of other minerals.