Yu Chuanlong (China Medical Science and Technology Press)
Amino acids and health of the elderly
The American space shuttle Discovery sent Glenn (77), the world's oldest astronaut, into space. For the elderly, this day is called the greatest day and the most eye-catching day. Glenn will explore space again in his later years. He wants to help medical science experiments. Protein decomposition of the elderly and the biological experiment of human amino acids are important research. Amino acids and the health of the elderly should be studied not only on earth, but also in space. Because amino acids are related to the life span and aging of the elderly, this is too important. Why is it important? You will know in the following paragraphs. 1. Physiological changes and amino acids in the elderly
It is generally believed that people are old after 60. The physiological and nutritional status of the elderly changes with the progress of the elderly. The changes of protein in the elderly can be summarized in two ways: one is to synthesize tissue protein and various active substances; The second is decomposition, which organizes protein decomposition to produce energy and waste. For growing infants and adolescents, synthesis is greater than decomposition, so the body grows gradually; For the average adult, synthesis equals decomposition, so the weight is relatively stable. For the elderly, in the process of human aging, protein metabolism is dominated by decomposition, while synthetic metabolism is gradually slow, and protein in the body is gradually consumed, often showing a negative nitrogen balance. For example, hemoglobin synthesis is reduced, so anemia is a common senile disease; Due to the function of enzymes and the decrease of small intestine function, protein is not fully decomposed during absorption, and peptides in the body increase and free amino acids decrease. Low renal function in the elderly affects the reabsorption of amino acids, and the decline of liver function also reduces the utilization rate of peptides. In recent years, it has been reported that the elderly are given the same nutritional conditions as young adults, but the plasma amino acids (Valeriana officinalis, leucine, lime, eggs, silk and alanine) of the elderly are reduced, especially the branched-chain amino acids (Valeriana officinalis, leucine and isoleucine) are insufficient. Some people think that high concentration of branched-chain amino acids can provide synthesis. When supplying branched-chain amino acids, it can provide energy by producing adenosine triphosphate (ATP), reduce protein decomposition and enhance the synthesis of protein by promoting insulin secretion. Branched-chain amino acids have been used to maintain nitrogen balance and promote protein synthesis abroad. There are amino acids for liver disease, kidney disease and children in China.
Due to the absorption or utilization of amino acids. Aging affects immune function, and changes in immune activity also affect the functions of other organs. Such as infection, cancer, immune complex disease, autoimmune disease, amyloidosis and other diseases increase in the elderly, which easily leads to aging and death.
2. Amino acids and longevity
In order to promote the health of the elderly, such as anti-aging, improving the body's resistance and promoting the function of immune mechanism, food needs to be rich in trace elements or sugars. However, the material basis of immunity is protein, and there is no immune substance in human body that is not made of protein. Such as immunoglobulin, antibody, antigen, complement, etc. Even the content of protein in white blood cells, lymphocytes and phagocytes is above 90%. Therefore, if the human body is not short of protein or amino acids, the above trace elements and polysaccharides will play a role. If it is missing, no amount of use is useless. With the development of nutrition and biochemistry, new research shows that although the human body can synthesize some non-essential amino acids, it is easy to lack them in severe stress (including mental stress, anxiety and ideological burden) or some diseases. If it is lacking, it will have a bad influence on the human body. These amino acids are called conditionally essential amino acid. Such as taurine, arginine and glutamine.
Under normal circumstances, the lack of essential amino acids will reduce the immune response of body fluids. For example, in tryptophan-deficient rats, IgG and IgM receptors are inhibited, but normal antibody production can be maintained when tryptophan is supplemented again; The lack of phenylalanine and tyrosine can inhibit the reaction of rat immune cells to tumor cells; The deficiency of methionine and cystine can also lead to the obstacle of antibody synthesis. It has been proved that the balance of amino acids also has this adverse effect. Therefore, essential amino acids play an important role in immunity. To prolong the life span of the elderly, we must improve immunity and pay attention to the supply of essential amino acids. At present, the essential amino acids closely related to life span are:
Taurine: The source of taurine in human body is self-synthesis and intake from diet. The biosynthesis of taurine is that methionine is converted into cystine by vulcanization and then synthesized by cystine. After 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 their bodies, so they need to take taurine from their diet to meet their needs. It is reported that taurine plays a role in the aging of the central nervous system; The degeneration of nervous system in old age is one of the most complicated and profound processes in all systems of the whole body. The aging of central nervous system has obvious changes in morphology or biochemistry, and the mechanism of synthesis, release, reabsorption and transport of monoamine and amino acid neurotransmitters has increased year by year. Lipofuscin is a characteristic substance in the aging process, and the increase of lipofuscin in the brain is one of the signs of nerve aging. When a large amount of lipofuscin accumulates in the cytoplasm of neurons, the nucleus and cytoplasm are compressed and deformed, which affects the normal metabolic function of neurons. The content of lipofuscin in tissues increases obviously during aging, but taurine can decrease it, increase the activity of superoxide dismutase (SOD), and inhibit the modification of low density lipoprotein (LDL) by malondialdehyde (MDA), a product of lipid peroxidation. At the same time, the reaction product of taurine and glucose shows strong antioxidant effect, which can prevent egg yolk lecithin from being oxidized into lipid peroxide, so it has obvious anti-aging effect.
Arginine: Although arginine is not an essential amino acid, it cannot maintain nitrogen balance and normal physiological function under severe stress (such as disease or injury) or arginine deficiency, so it is a conditionally essential amino acid. According to the latest theory, arginine is an essential substance in the enzymatic metabolic pathway of nitric oxide (NO) reacting with citrulline. The main biochemical function of NO or relaxation factor derived from endothelial cells is to stimulate the body to increase the level of cyclic guanylate in phagocytes and stimulate the production of interleukin to regulate the phagocytic function of macrophages. Arginine-related NO enzyme system has also been found in vascular endothelial cells, Cooper's cells in brain tissue and liver, which can lead to hormone secretion in these organs and tissues, thus playing an immune role. Amino acid injection can also be used to improve the immunity of the elderly.
Glutamine: Under normal circumstances, it is a non-essential amino acid. However, under stress conditions such as strenuous exercise, injury and infection. The demand for glutamine greatly exceeds the ability of the body to synthesize glutamine, which reduces the content of glutamine in the body, and this decrease will reduce the synthesis of protein, atrophy of intestinal mucosa and low immune function, so it is also called conditionally essential amino acid.
Recently, it is found that the intestine is the largest immune organ and the third barrier of the human body. The first two barriers are blood-brain barrier and placental barrier. If there is no nutrition supply in the intestine, the intestine will be malnourished, which will weaken the immune function of the intestine and lead to bacterial translocation. Animal experiments have proved that if animals are supplemented with total intravenous infusion or essential diet without glutamine, the villi of small intestine will shrink, the intestinal wall will become thinner and the intestinal immune function will be reduced. Intravenous infusion of 2% glutamylase (about 25% of total amino acids) has a significant effect on restoring intestinal villi atrophy and immune function. Glutamine plays an important role in maintaining the function of intestinal mucosa and improving the immunity, especially for the elderly.
3. How do the elderly scientifically supplement amino acids?
With the increase of age, the amount of amino acids required by the elderly decreases. The protein quality of a healthy elderly protein is 60% ~ 70% of that of young adults. This may be related to the decrease of skeletal muscle, but it can't be concluded that protein needs to decrease in the elderly. The elderly are mainly catabolic, with decreased secretion of gastric juice and pepsin, decreased acidity of gastric juice and decreased digestion and absorption of protein. In addition, the intake of heat energy is low, and the retention of dietary nitrogen is reduced, so the elderly need less protein than adults. Generally speaking, in a normal diet, the intake of protein is 0.7 ~ 1.0g/kg body weight to maintain the nitrogen balance, and 1.0 ~ 1.2g/kg body weight to achieve the balance. Accordingly, the daily supply of protein is about 60 ~ 75g, of which 1/3 is animal protein. If the heating ratio in protein is considered, 12% ~ 14% is more suitable. Studies on amino acid metabolism show that the requirements of threonine, tryptophan and methionine are different from those of young people, so the suitable pattern of essential amino acids can change with age. Therefore, the quality of protein supply for the elderly is more important. Generally speaking, drinks and food are rich in essential amino acids, which is beneficial to the synthesis of protein.
It is suggested that the reasonable structure of the daily diet of the elderly is:
1. An egg; 2. A bowl of milk (not necessarily with sugar); 3.500g of fruits and vegetables (variety); 4. 100g clean meat, including livestock, poultry and fish; 5.50g of bean products (including tofu, yuba, thousand pieces, bean cakes and various beans themselves).
Products, such as douchi, douchi, boiled whole beans); 6.500 grams of grain (including rice, flour, miscellaneous grains, potatoes and sugar); 7. Drink soup every day, one bowl for each meal; 8. If you are weak and sick, take 50 ml of amino acid oral liquid every morning and evening and replenish it quickly.
Nutrition.
These eight items are based on the value of "one". The purpose is generalization and vagueness, and all projects have great freedom. For example, vegetable varieties can be selected and changed; Meat can be one or more kinds, put in meals and soup, etc. Of course, it can also be made into more forms; Meat and beans can be transformed into each other and complement each other. For example, milk can be replaced by dairy products, yogurt and milk powder. Xiyangyang Feng Ba amino acid oral liquid is made of crystalline L- amino acid, which is prepared according to human milk and FAO/ WHO model. It can be directly absorbed by human body and is a good nutritional supplement.
Can meet the requirements of protein and amino acids, and ensure anti-aging.