References:
Physiological functions of amino acids
Amino acids through the peptide bond linked together to become peptides and proteins. Amino acids, peptides and proteins are the basic components of the tissue cells of organic organisms and play a pivotal role in life activities.
Some amino acids not only form proteins, but also participate in some special metabolic reactions, showing some important characteristics.
(1) Lysine
Lysine is an alkaline essential amino acid. Because the lysine content in cereal food is very low, and in the processing process is easily destroyed and lack of, so it is called the first limiting amino acid.
Lysine can regulate the body's metabolic balance. Lysine provides structural components for the synthesis of carnitine, which leads to the synthesis of fatty acids in cells. Adding a small amount of lysine to food can stimulate the secretion of pepsin and gastric acid, increase the effectiveness of gastric juice secretion, enhance appetite, and promote the growth and development of young children. Lysine can also improve the absorption of calcium and its accumulation in the body, accelerating bone growth. If the lack of lysine, it will cause gastric juice to be insufficient and anorexia, nutritional anemia, resulting in the central nervous system is blocked, poor development.
Lysine in medicine can also be used as a diuretic auxiliary drugs, treatment of lead poisoning caused by a decrease in blood chloride, but also with acidic drugs (such as salicylic acid, etc.) to generate salt to alleviate the adverse effects of methionine can be combined to inhibit severe hypertension.
Herpes simplex virus is the cause of herpes labialis, herpes pyoderma, and genital herpes, while its close genus, herpes zoster virus, is the causative agent of chickenpox, herpes zoster, and infectious mononucleosis. Research published in 1979 by the Lilly Research Laboratory in Indianapolis showed that lysine supplementation accelerated recovery from herpes infections and inhibited their recurrence.
Long-term administration of lysine antagonizes another amino acid, arginine, which promotes the growth of herpes viruses.
(2) Methionine
Methionine is a sulfur-containing essential amino acid that is closely related to the metabolism of various sulfur-containing compounds in living organisms. When methionine is deficient, it can cause loss of appetite, slowed growth or no weight gain, enlarged kidneys and iron buildup in the liver, and eventually lead to liver necrosis or fibrosis.
Methionine can also use the methyl group it carries to methylate toxic substances or drugs and play a detoxifying role. Therefore, methionine can be used to prevent and control liver diseases such as chronic or acute hepatitis and cirrhosis, and can also be used to alleviate the toxic reactions of harmful substances such as arsenic, trichloromethane, carbon tetrachloride, benzene, pyridine and quinoline.
(3) Tryptophan
Tryptophan can be converted to generate 5-hydroxytryptophan, an important neurotransmitter in the human brain, and 5-hydroxytryptophan has the effect of neutralizing adrenaline and norepinephrine, and can improve sleep duration of sleep. When the level of 5-hydroxytryptamine in the brain of an animal decreases, it shows abnormal behavior, neurological hallucinations, and insomnia. In addition, 5-hydroxytryptophan has a strong vasoconstrictor effect and can be found in many tissues, including platelets and intestinal mucosal cells, and the body stops bleeding after injury by releasing 5-hydroxytryptophan. Tryptophan is often used in medicine as an anti-smothering agent, anti-spasmodic agent, gastric secretion regulator, gastric mucosal protector and strong anti-coma agent.
(4) Valine, leucine, isoleucine and threonine
Valine, leucine and isoleucine are all branched-chain amino acids, and all are essential amino acids. When valine is deficient, the central nervous system function of rats is disturbed and ****济失调而出现四肢震颤. Through the anatomical section brain tissue, found to have red nucleus cell degeneration phenomenon, advanced cirrhosis patients due to liver function damage, easy to form hyperinsulinemia, resulting in a reduction in the blood of branched-chain amino acids, branched-chain amino acids and aromatic amino acid ratio from the normal person's 3.0 ~ 3.5 to 1.0 ~ 1.5, so commonly used valine and other branched-chain amino acids of the injection of the treatment of hepatic failure and other diseases. In addition, it can also be used as a therapeutic agent to accelerate wound healing.
Leucine can be used in the diagnosis and treatment of sudden hyperglycemia in children, and can also be used as a dizziness treatment agent and nutritional tonic. Isoleucine treats nervous disorders, loss of appetite and anemia, and is also extremely important in muscle protein metabolism.
Threonine is one of the essential amino acids and is involved in fat metabolism; hepatic steatosis occurs when threonine is deficient.
(5) Aspartic acid, asparagine
Aspartic acid promotes the tricarboxylic acid cycle through the deamination of oxaloacetic acid, so it is an important component of the tricarboxylic acid cycle. Aspartic acid is also closely related to the ornithine cycle and is partially responsible for converting ammonia in the blood to urea for excretion. At the same time, aspartic acid is the raw material for the synthesis of nucleic acid precursors such as orotate.
Usually, aspartic acid is made into salts of calcium, magnesium, potassium, or iron. This is because these metals, when combined with aspartic acid, are able to enter the cell through the cell membrane via the active transport pathway to play a role in the cell. A mixture of potassium and magnesium salts of aspartate is primarily used to eliminate fatigue and is used clinically to treat heart disease, liver disease, diabetes, and other conditions. Potassium aspartate salts are used to treat hypokalemia, and iron salts are used to treat anemia.
The proliferation of different cancer cells requires the consumption of large amounts of a specific amino acid. Finding analogs of this amino acid - metabolic antagonists - is considered an effective means of treating cancer. The enzyme asparaginase blocks the proliferation of cancer cells (leukemia) that require asparagine. An analog of asparagine, S-carbamoyl-cysteine, has been tested in animal studies for its effectiveness against leukemia. At present, there are more than 10 kinds of amino acid anticancer substances have been tried, such as N-acetyl-L-phenylalanine, N-acetyl-L-valine, etc., and the inhibition rate of some of them on cancer cells can be as high as 95% or more.
(6) Cystine, cysteine
Cystine and cysteine are sulfur-containing non-essential amino acids, which can reduce the body's need for methionine. Cystine is indispensable for the formation of skin, accelerates the healing of burn wounds and chemical protection from radiation damage, and stimulates the increase of red and white blood cells.
The sulfhydryl group (-SH) carried by cysteine has a number of physiological effects, which can alleviate the degree of toxicity of toxic or poisonous drugs (phenol, benzene, naphthalene, cyanide ions), and also has a preventive effect on radiation. N-acetyl-L-cysteine, a derivative of cysteine, has a viscosity-lowering effect due to the action of sulfhydryl groups, and can be used as a mucolytic agent to prevent and control coughing sputum such as bronchitis and other difficulties in expectoration. In addition, cysteine promotes hair growth and can be used in the treatment of alopecia areata. Other derivatives, such as L-cysteine methyl ester hydrochloride can be used in the treatment of bronchitis, nasal mucous membrane exudative hair inflammation.
(7) Glycine
Glycine is the simplest amino acid, which can be produced by the loss of a carbon from serine. Glycine is involved in the synthesis of purines, porphyrins, creatine, and glyoxalate, which contributes to the hereditary disease oxaluria by producing oxalic acid from its oxidation. In addition, glycine binds to a wide variety of substances, causing them to be excreted in bile or urine. In addition, glycine provides a source of nitrogen for non-essential amino acids and improves the tolerance of amino acid injections in the body. Using glycine together with glutamic acid and alanine is effective in combating the complications of prostate enlargement, dysuria, frequent urination, and residual urine.
(8) Histidine
Histidine is a non-essential amino acid for adults, but an essential amino acid for young children. When a small amount of histidine is added to the diet of patients with chronic uremia, the rate of amino acid incorporation into hemoglobin increases, and nephrogenic anemia is reduced, so histidine is also an essential amino acid for patients with uremia.
The imidazole group of histidine can form coordination compounds with Fe2+ or other metal ions to promote iron absorption, and thus can be used to prevent anemia. Histidine can reduce the acidity of gastric juice, ease the pain of gastrointestinal surgery, reduce vomiting and heartburn during pregnancy, inhibit digestive ulcers caused by vegetative nervous tension, and is also effective in allergic diseases such as asthma. In addition, histidine can dilate blood vessels, reduce blood pressure, clinically used in angina pectoris, cardiac insufficiency and other diseases. Rheumatoid arthritis patients with a significant reduction in blood histidine content, the use of histidine found that their grip strength, walking and blood sedimentation and other indicators have improved.
Histidine decarboxylates to form histamine under the action of histidine decarboxylase. Histamine has a strong vasodilatory effect and is associated with a variety of allergic reactions and inflammation. In addition, histamine stimulates pepsin and gastric acid.
(9) Glutamate
Glutamate and aspartic acid have excitatory transmitter effects; they are the most abundant amino acids in the mammalian central nervous system, and their excitatory effects are limited to the center. When glutamate content reaches 9%, an increase of just 10-15 mol of glutamate can have an excitatory effect on cortical neurons. Therefore, glutamate is essential for improving and maintaining brain function.
Glutamate is decarboxylated by glutamic acid decarboxylase to form γ-aminobutyric acid, which is a substance present in brain tissue that has an inhibitory effect on central nervous system excitability, and affects cellular metabolism and cellular function when the level of γ-aminobutyric acid decreases.
Multiple derivatives of glutamate, such as dimethylaminoethanol acetylglutamate, are used clinically to treat movement disorders, memory disorders, and encephalitis due to cerebral vascular disorders. gamma-Aminobutyric acid is effective for memory disorders, speech disorders, paralysis, and hypertension, and gamma-amino beta -hydroxybutyric acid is effective for localized paralysis, memory disorders, speech disorders, instinctive renal hypertension, epilepsy and mental retardation.
Glutamic acid, like aspartic acid, is also closely related to the tricarboxylic acid cycle and is used in the treatment of conditions such as hepatic coma. Glutamine, an amide derivative of glutamic acid, has a significant effect on gastric ulcers due to the transfer of the amino group of glutamine to glucose to produce glucosamine, a constituent of mucin in the epithelial tissue of the mucous membrane of the digestive apparatus.
(10) Serine, alanine and proline
Serine is the precursor for the synthesis of purine, thymine and choline, alanine plays an important role in the process of protein synthesis in vivo, which is metabolized in vivo through the deamination of ketoacids to generate sugar in accordance with the glucose metabolic pathway. The pyrrole ring in the proline molecule is structurally closely related to hemoglobin. Hydroxyproline is one of the components of collagen. An imbalance in the concentration of proline and hydroxyproline in the body causes a weakening of the toughness of the teeth, cartilage in the bones and ligamentous tissue. Proline derivatives, in conjunction with diuretics, have antihypertensive effects.
Taurine
Taurine is a constituent of taurine.
Taurine is commonly found in animal milk, brain and heart, and is most abundant in muscle, where it exists in free form and is not involved in protein metabolism. It exists only in algae in plants and has not been found in higher plants. Taurine in the body is metabolized from cysteine.
A deficiency of taurine affects growth, vision, and the normal growth of the heart and brain.
Patients who are infected by bacteria, due to the large number of bacteria consume taurine in the body, will also form a taurine deficiency, occurring in the fundus of the eye retinal electroretinogram changes, and supplementation of taurine will make the fundus of the eye lesions better Due to the fact that humans can only be limited to the synthesis of taurine, so the dietary taurine is very important.
Dairy products are low in taurine. In poultry, black poultry meat has a higher taurine content than white meat. Comparison of seafood and poultry, livestock, to seafood in the highest taurine content, such as oysters, clams and tamari in taurine can be as high as 400mg/100g or more, at the same time, heating and cooking on its taurine content has little effect. A variety of everyday foods, including grains, fruits and vegetables, do not contain taurine.
Arginine
(a) Arginine is a constituent of the ornithine cycle and has an extremely important physiological function. Eating more arginine can increase the activity of arginase in the liver, which helps to convert ammonia in the blood into urea and excrete it. Therefore, arginine is quite effective in diseases such as hyperammonemia and liver dysfunction.
Arginine is a double-base amino acid, although it is not an essential amino acid for adults, but in some cases, such as immature development of the body or under severe stress conditions, if there is a lack of arginine, the body will not be able to maintain positive nitrogen balance and normal physiological functions. Patients who lack arginine will lead to high blood ammonia, or even coma. If an infant is congenitally deficient in some of the enzymes of the urea cycle, arginine is also necessary for it, otherwise it cannot maintain its normal growth and development.
The important metabolic function of arginine is to promote the healing effect of the wound, it can promote the synthesis of collagen tissue, so it can repair the wound. Elevated arginase activity can be observed in the wound secretion, which also indicates that the need for arginine near the wound is greatly increased. Arginine can promote microcirculation around the wound and promote early wound healing.
The immunomodulatory function of arginine prevents the degeneration of the thymus gland (especially after injury), and supplementation with arginine increases the weight of the thymus gland and promotes the growth of lymphocytes in the thymus gland.
Supplementation of arginine also reduces the size of animals with tumors, reduces the rate of tumor metastasis, and improves the live time and survival rate of animals.
In the immune system, in addition to lymphocytes, the vitality of phagocytes is also related to arginine. Adding arginine activates their enzyme systems, making them more capable of killing target cells such as tumor cells or bacteria.
Dr. Zheng Jianxian, Professor, South China University of Technology
Amino acids and human health
Amino acids are the most basic substances that make up the proteins of living organisms and are related to life activities. It has a special physiological function in the antibody, is one of the indispensable nutrients in the organism.
I. The basic substances that make up the human body, the material basis of life
1. One of the most basic substances that make up the human body
The most basic substances that make up the human body, there are proteins, lipids, carbohydrates, inorganic salts, vitamins, water, and dietary fiber.
Amino acids, which are the basic units of protein molecules, are undoubtedly one of the most basic substances in the human body.
There are more than 20 kinds of amino acids that constitute the human body, they are: tryptophan, methionine, threonine, valine, lysine, histidine, leucine, isoleucine, alanine, phenylalanine, cystine, cysteine, arginine, glycine, serine, tyrosine, 3.5.diiodotyrosine, glutamic acid, aspartic acid, proline, hydroxyproline, arginine, citrulline, ou amino acid, citrulline, ouabain, etc. These amino acids are found in nature and can be synthesized in plants, while the human body cannot synthesize all of them. Eight of these amino acids cannot be synthesized by the human body and must be supplied by food, and are called "essential amino acids". These 8 essential amino acids are: tryptophan, threonine, methionine, valine, lysine, leucine, isoleucine and phenylalanine. The others are "non-essential amino acids". Histidine can be synthesized in the body, but the rate of synthesis is not sufficient to meet the body's needs, and some people also classify it as an "essential amino acid". Cystine, tyrosine, arginine, serine and glycine may cause physiological dysfunction in the long-term lack of, and listed as "semi-essential amino acids", because they can be synthesized in the body, but its synthesis of raw materials are essential amino acids, and cystine can replace 80% to 90% of methionine, tyrosine can replace 70% to 75% of the phenylalanine, play a role in the essential amino acids. Phenylalanine, play the role of essential amino acids, the above amino acids are divided into "essential amino acids", "semi-essential amino acids" and "non-essential amino acids" 3 categories, according to its nutritional function. Functions; such as its metabolic pathway in the body can be divided into "ketogenic amino acids" and "sugar amino acids"; according to its chemical properties can be divided into neutral amino acids, acidic amino acids and alkaline amino acids, most of the amino acids belong to the neutral.
2. The material basis of life metabolism
The generation, existence and demise of life, none of which is related to protein, as Engels said: "Protein is the material basis of life, life is a form of protein existence." If the lack of protein in the human body, the light body quality decline, development retardation, weakened resistance, anemia and weakness, the heavy formation of edema, and even life-threatening. Once the loss of protein, life will no longer exist, so some people call protein as "the carrier of life". It can be said that it is the first element of life.
The basic unit of protein is amino acid. If the human body lacks any one of the essential amino acids, it can lead to abnormal physiological functions, affecting the normal metabolism of antibodies, and finally lead to disease. Similarly, if the human body is deficient in certain non-essential amino acids, antibody metabolism disorders can arise. Arginine and citrulline are important for the formation of urea; insufficient intake of cystine can cause a decrease in insulin and an increase in blood glucose. Another example is that the need for cystine and arginine increases dramatically after trauma, and if they are lacking, they cannot synthesize proteins successfully even if they have enough calories. In short, amino acids in the human body through metabolism can play the following roles: ① synthesis of tissue proteins; ② into acids, hormones, antibodies, creatine and other ammonia-containing substances; ③ into carbohydrates and fats; ④ oxidation into carbon dioxide and water and urea, producing energy. Therefore, the presence of amino acids in the human body not only provides an important raw material for the synthesis of proteins, but also for the promotion of growth, normal metabolism, and maintenance of life provides the material basis. If the human body lacks or reduces one of them, the normal life metabolism of the human body will be impaired, and even lead to the occurrence of various diseases or the termination of life activities. From this, we can see that the amino acids in the human body life activities appear to be how much need.
Second, the status and role of food nutrition
Human beings in order to survive the need to ingest food, in order to maintain the normal physiology of the antibody, biochemistry, immune function, as well as growth, metabolism, and other life activities, food in the body through digestion, absorption, metabolism, and to promote the antibody growth, development, wisdom, health, anti-disease, prolonging the life of a comprehensive process known as nutrition. The active ingredients in food are called nutrients.
As the most basic substances that constitute the human body's proteins, lipids, carbohydrates, inorganic salts (i.e., minerals, including macronutrients and trace elements), vitamins, water and dietary fiber, but also nutrients needed by the body. They have their own unique nutritional function in the body, but in the metabolic process and closely linked, *** with the participation, promote and regulate life activities. The body through the food and the outside world, to maintain the relative constancy of the inner environment, and to complete the unity and balance of the internal and external environment.
What is the role of amino acids in these nutrients?
1. The digestion and absorption of protein in the body is accomplished through amino acids
As the first nutritional element of protein in the body, its role in food nutrition is obvious, but it can not be utilized directly in the body, but through the amino acids into small molecules after being utilized. That is, it is not directly absorbed by the body in the gastrointestinal tract of the human body, but in the gastrointestinal tract after a variety of digestive enzymes, high molecular proteins are broken down into low molecules of polypeptides or amino acids, and then absorbed in the small intestine, along the hepatic portal vein into the liver. One part of the amino acids undergoes decomposition or synthesis of proteins in the liver; the other part of the amino acids continues to be distributed to various tissues and organs along with the bloodstream, and is left to be selected for the synthesis of a variety of tissue-specific proteins. Under normal circumstances, amino acids enter the bloodstream at a rate almost equal to their rate of output, so the amino acid content of the blood of normal people is fairly constant. For example, in terms of amino nitrogen, the content is 4-6 milligrams per 100 milliliters of plasma and 6.5-9.6 milligrams per 100 milliliters of blood cells. After a full meal of protein, a large number of amino acids are absorbed, the amino acid level in the blood is temporarily elevated, and after 6-7 hours, the content returns to normal. This indicates that amino acid metabolism in the body is in dynamic balance, with blood amino acids as its balance hub, and the liver is an important regulator of blood amino acids. Therefore, food proteins are digested and decomposed into amino acids, which are absorbed by the body, and the antibodies use these amino acids to synthesize their own proteins. The body's need for protein is actually a need for amino acids.
2. Nitrogen balance
When the quality and quantity of protein in the daily diet is appropriate, the amount of nitrogen ingested is equal to the amount of nitrogen excreted by the feces, urine and skin, which is called the total nitrogen balance. In fact, it is the balance between the constant synthesis and decomposition of proteins and amino acids. Normal people should keep the daily intake of protein within a certain range, sudden increase or decrease in intake, the body can still regulate the metabolism of protein to maintain nitrogen balance. If we eat too much protein, beyond the body's ability to regulate, the balance mechanism will be destroyed. Do not eat protein, the body still tissue protein decomposition, negative nitrogen balance continues to appear, if you do not take timely measures to correct, will eventually lead to the death of the antibody.
3. Transformation into sugar or fat
Amino acid catabolism produces a-keto acid, with different characteristics, the metabolic pathway of sugar or lipid metabolism. a-keto acid can be synthesized into new amino acids, or transformed into sugar or fat, or into the tricarboxylic acid cycle oxidation and decomposition of CO2 and H2O, and release of energy. energy.
4. Involved in the composition of enzymes, hormones, some vitamins
Enzymes are chemically proteins (composed of amino acid molecules), such as amylase, pepsin, cholinesterase, carbonic anhydrase, aminotransferase and so on. Nitrogen-containing hormones are composed of proteins or their derivatives, such as growth hormone, thyroid-stimulating hormone, adrenaline, insulin, and enteric fluid-stimulating hormone. There are vitamins that are transformed from amino acids or exist in combination with proteins. Enzymes, hormones and vitamins play a very important role in regulating physiological functions and catalyzing metabolic processes.
5. Essential amino acid requirements
Essential amino acid requirements for adults is about 20% of the protein requirements, -37%.
Three, in the application of medical
Amino acids in medicine is mainly used to prepare compound amino acid infusion, but also used as therapeutic drugs and for the synthesis of peptide drugs. At present, there are more than 100 kinds of amino acids used as drugs, including 20 kinds of amino acids that constitute proteins and more than 100 kinds of amino acids that constitute non-proteins.
The compound preparation composed of many kinds of amino acids occupies a very important position in the modern intravenous nutrition infusion and "elemental diet" therapy, which plays an active role in maintaining the nutrition of the critically ill patients and saving their lives, and has become one of the indispensable medicinal varieties in modern medical treatment.
Glutamic acid, arginine, aspartic acid, cystine, L-dopa and other amino acids work alone to treat a number of diseases, mainly used in the treatment of liver diseases, digestive diseases, cerebral diseases, cardiovascular diseases, respiratory diseases, as well as used to improve muscle vitality, pediatric nutrition and detoxification. In addition amino acid derivatives have shown promise in cancer treatment.
Four, the relationship with aging
Elderly people if the lack of protein in the body to decompose more and slower synthesis. Therefore, generally speaking, the elderly than young adults need more protein, and the demand for methionine, lysine is higher than young adults. 60 years old and above should be consumed every day about 70 grams of protein, and the requirements of the protein contains essential amino acids complete and appropriate ratio, so that high-quality proteins, prolonged life.
Yu Chuanlong (China Medical Science and Technology Publishing)
Amino acids and health in old age
The U.S. space shuttle Discovery sent the world's oldest astronaut (77) Glenn into space. This day is known as the greatest day for the elderly and attracts the most attention. In his twilight years, Glenn will go back to space, he wants to help medical science experiments. The elderly protein breakdown, the human body amino acid biology experiment is an important research. Amino acids and the health of the elderly, not only on Earth to study, but also in space. This is because amino acids are so important to the longevity and aging of the elderly. Why it is important can be seen from the following description. 1. Physiological changes in old age and amino acids
Generally believed that people into the 60 years of age or older is into the old age. The physiological and nutritional status of the elderly changes with the progress of old age. Protein changes in the elderly body is summarized in two: one is synthesis, synthesis of tissue proteins and a variety of active substances; the second is decomposition, the decomposition of tissue proteins, produce energy, produce waste. For growth and development of infants and adolescents, synthesis is greater than decomposition, and thus the body grows gradually; for adults in general, synthesis is equal to decomposition, and thus the weight is relatively stable. For the elderly, the human body aging process of protein metabolism is mainly decomposition, anabolism gradually slow, the body's protein is gradually consumed, often a negative nitrogen balance. For example, hemoglobin synthesis is reduced, so anemia is a common geriatric disease; due to the role of enzymes and small intestine function decline, protein absorption process is not sufficiently decomposed, the body peptides increase, free amino acids decrease. Due to the low renal function of the elderly affects the reabsorption of amino acids, due to the decline in liver function, the utilization of peptides is also reduced. Recent studies have reported that the elderly and young people are given the same nutritional conditions, but the plasma amino acid (val, leucine, tyrosine, lysine, methionine, serine, alanine) content of the elderly is reduced, especially the branched-chain amino acids (val, leucine, isoleucine) show insufficient. It is believed that high concentration of branched-chain amino acids has a role in providing synthesis, and when supplemented with branched-chain amino acids, it can reduce protein catabolism by generating adenosine triphosphate (ATP) for energy, and enhance protein synthesis by promoting insulin secretion. Branched-chain amino acids have been used in clinics to maintain nitrogen balance and promote protein synthesis. Domestic special amino acids have been used in liver disease, kidney disease and children.
Due to the absorption or utilization of amino acids. Due to aging and affect the immune function, changes in immune activity also affect the function of other organs, such as infection, cancer, immune complex disease, autoimmune disease, amyloidosis incidence in old age are increased, easy to cause aging disease and death.
2. Amino acids and longevity
In order to promote the health of the elderly, such as anti-aging, improve body resistance, promote the function of the immune mechanism, the need for food rich in trace elements or sugar. However, the material basis of immunity is protein, there is no human immune material is not composed of protein. Such as immunoglobulins, antibodies, antigens, complements, etc., even white blood cells, lymphocytes and phagocytes and other intracellular protein content of more than 90%. Therefore, if the human body is not deficient in proteins or amino acids, the above-mentioned trace elements and polysaccharides will work. If there is a deficiency, no matter how much they are used, they will not work. With the progress of nutrition and biochemistry, new research has shown that although the body can synthesize a certain non-essential amino acid supplementation, but in a state of severe stress (including mental stress, anxiety, burden of thought) or certain diseases are prone to deficiency. If a deficiency occurs, it will have a harmful effect on the human body, and these amino acids are called conditionally essential amino acids. Examples include taurine, arginine and glutamine.
Deficiencies of essential amino acids under normal conditions can reduce the humoral immune response. For example, tryptophan deficient rats, its IgG and IgM receptor inhibition, and when reintroduced tryptophan can maintain normal antibody production; phenylalanine and tyrosine are deficient, can inhibit the rat's immune cells to respond to the tumor cells; methionine and cystine deficiencies, but also cause antibody synthesis disorders. It has been shown that the balance of amino acids also has this unfavorable effect. Thus essential amino acids play an important role in immunity, and in order to prolong the life span of the elderly, it is necessary to improve immunity and emphasize the supply of essential amino acids. Currently, the essential amino acids related to longevity that are the subject of popular research are:
Taurine: The source of taurine in the human body is self-synthesis, and the second is from dietary intake. Taurine biosynthesis from methionine by sulfation into cystine, and synthesized from cystine, which undergoes a series of enzymatic reactions, many higher animals, including humans have lost the ability to synthesize enough taurine to maintain the overall level of taurine in the body, the need for dietary intake of taurine in order to meet the needs of the body. The role of taurine in central nervous system aging has been reported; degenerative changes in the nervous system in old age are one of the most complex and profound processes in all systems of the body, and aging of the central nervous system is markedly altered at the morphologic or biochemical level, with incremental changes in monoamine and amino acid neurotransmitters in terms of their synthesis, release, reabsorption, and transport mechanisms. Lipofuscin is a characteristic substance in the aging process, and the increase of brain lipofuscin is one of the signs of neural aging changes. When the neuronal cytoplasm accumulates a larger amount of lipofuscin, the nucleus of the cell and the cytoplasm of the cell are pressurized and deformed, which affects the normal metabolic function of neurons. When aging, the content of lipofuscin in tissues increases significantly, and taurine can make the decline, and increase the activity of superoxide dismutase (SOD), and can inhibit the modification of low-density lipoprotein (LDL) by the lipid peroxidation product malondialdehyde (MDA). Meanwhile, the reaction products of taurine and glucose showed strong antioxidant effects and were able to prevent the oxidation of egg yolk lecithin into lipid peroxides, thus having significant anti-aging effects.
Arginine: Although arginine is not an essential amino acid, it is a conditionally essential amino acid because it cannot maintain nitrogen balance and normal physiological functions under severe stress (such as disease or injury) or when arginine is deficient. Recent theories suggest that arginine is essential for the enzymatic pathway of nitric oxide (NO) reaction with citrulline, and that the main biochemical effect of NO or endothelium-derived relaxing factors is to stimulate the body to increase cyclic guanosine levels in phagocytes and to stimulate the production of interleukins to regulate bacterial phagocytosis by macrophages. The NO enzyme system associated with arginine is also found in the endothelial cells of blood vessels, brain tissue, and kupffer cells of the liver, which leads to hormone secretion in these organs and tissues, thereby contributing to immune function. Amino acid injections can also be used to improve immunity in the elderly.
Glutamine: under normal circumstances, it is a non-essential amino acid, but in the case of strenuous exercise, injury, infection and other stressful situations, the amount of glutamine needs greatly exceed the body's ability to synthesize glutamine, so that the body's glutamine content is reduced, and this reduction will reduce protein synthesis, small intestinal mucosal atrophy and immune function, so it is also known as the condition of essential amino acids.
Recently, it is also known as a conditionally essential amino acid.
Recently, it has been discovered that the gut is the largest immune organ in the body, and is also the body's third barrier. The first two barriers are the blood-brain barrier and the placental barrier. If there is no nutritional supply in the intestines, the intestines will be malnourished, so that the immune function of the intestines is weakened with the occurrence of bacterial displacement of each other. Animal studies have demonstrated that if animals are supplemented with glutamine-free total intravenous fluids or elemental diets, the villi of the animal's small intestine undergo atrophy, the intestinal wall thins, and intestinal immune function is reduced. Provision of 2% glutaminase (approximately 25% of the total amino acids) in an intravenous infusion had a significant effect on restoring intestinal villous atrophy and immune function. The role of glutamine in the maintenance of intestinal mucosal function is indispensable in improving immunocompetence, especially in the elderly.
3, the elderly how to scientifically supplement amino acids
The elderly need for amino acids with age, the total amount of protein in the body declines, a healthy old man's total amount of protein for the 60% to 70% of young adults. This may be related to the reduction of skeletal muscle, but it can not be assumed that the elderly protein needs to be reduced. The elderly body to catabolism-based, gastric juice and pepsin secretion decreased, gastric acidity decreased, protein digestion and absorption decreased, in addition to low caloric intake, dietary nitrogen retention decreased, so the elderly protein needs are not less than the adults. Generally in the normal diet, protein intake 0.7 ~ 1.0g / kg body weight can maintain nitrogen balance, 1.0 ~ 1.2g / kg body weight can be balanced. Accordingly, the daily protein supply is roughly 60-75g, of which 1/3 is animal protein. If the protein heat supply ratio is considered, 12% to 14% is appropriate. Research in amino acid metabolism, suggesting that the need for threonine, tryptophan, methionine, etc. is different from that of young people, so the appropriate mode of essential amino acids
.