There are two kinds of vitamin A: one is formed vitamin A, that is, retinol, retinaldehyde, retinoic acid and so on. , only exists in animal food; The other is provitamin A, which can be transformed from α -carotene and β -carotene in plant foods.
physiological function
1. Protecting the eyes Vitamin A has always been called "eye protection agent". It is not only related to the secretion of tears, but also can adjust the adaptation of the eyes to the external light, so that they can keep their vision in the dark or light. It is an indispensable and important nutrient for maintaining eye health.
2. Promote the growth of human bones and protect human tissues and organs. Vitamin A plays a very important role in the development of human bones and the normal growth of the body. Because vitamin A can transform immature cells into bone cells and increase the number of bone cells, thus promoting the growth and development of bones and teeth.
In addition, vitamin A can promote mucus secretion. Prevent bacterial infection, thus protecting the normal operation of various tissues and organs of the body and maintaining the healthy operation of the respiratory system.
3. Enhance human immunity and prevent cancer. Vitamin A can improve the immune function of cells and body fluids, and enhance anti-infection ability and resistance to diseases. According to clinical observation, children taking vitamin A in moderation can obviously reduce the number of respiratory tract infections or shorten the course of disease and relieve symptoms.
Vitamin A is also involved in the synthesis of interstitial mucopolysaccharides, which plays a role in cell adhesion and protection. It is helpful to protect the health of skin, nose, throat, intima of respiratory organs, digestive system and urogenital epithelial tissues, and enhance the body's resistance to infectious diseases and parasitic infections.
In addition, vitamin A has a certain preventive and therapeutic effect on cancer caused by air pollution.
Poor performance
Insufficient intake of vitamin A will lead to vitamin A deficiency. Chronic diseases that cause skin and eyes.
1. Dry eye and night blindness When vitamin A deficiency affects the synthesis and regeneration of photosensitive substances in visual cells, dry eye, keratomalacia or night blindness with reduced tears will gradually appear. It is characterized by dry eyeball, corneal softening, decreased night vision ability and prolonged dark adaptation recovery time.
In severe cases, night blindness will occur. Vitamin A deficiency eye disease was first called "passerine" or "chicken blindness" in China. Sun Simiao in Tang Dynasty used sheep liver to treat passeriformes 0/300 years ago.
2. Keratosis folliculitis vitamin A deficiency is characterized by non-inflammatory prickly hair follicle papules on the skin, which are characterized by epithelial cell degeneration and increased keratinization. The epithelial cells of hair follicles are hyperkeratinized, and the hair follicles are filled with annular keratinocytes, forming keratin embolism, and the nipples, sebaceous glands and sweat glands atrophy. At first, the skin gradually became dry and scales increased. Later, hair follicle papules appeared, the size of conical needles, dark brown. After that, it gradually increased, densely and evenly distributed in limbs, neck, buttocks and back, which was significantly higher than the skin surface. There is a tapering keratin embolism in the center. Sometimes there is angular stomatitis. Hair is dry and dull, and there may be diffuse sparse shedding. Nails are not as bright as normal, and may have longitudinal ridges, transverse ridges, punctate depressions or become brittle.
3. Decline in immunity Vitamin A deficiency will reduce the immune function of the body and produce symptoms such as decreased immunity to respiratory infectious diseases.
When children are short of vitamin A, they are prone to growth retardation and skeletal dysplasia.
Lack of rationality
1. Green vegetables, carrots, animal livers, eggs and milk are rich in vitamin A.
If food lacks these substances for a long time, it will easily lead to primary vitamin A deficiency.
2. Gastroenteritis will affect the transformation of provitamin A into vitamin A, thus affecting the absorption and storage of vitamin A in the gastrointestinal tract. Therefore, in the case of gastroenteritis and long-term diarrhea, it is easy to lead to secondary vitamin A deficiency.
therapeutic regimen
1. vitamin a capsules, each time 1 capsule, three times a day, mainly used to prevent and treat vitamin a deficiency such as night blindness, dry eye and keratosis of skin hair follicles; If gastrointestinal absorption is not good, intramuscular injection can be used. Generally, vitamin A deficiency improves about 1 month after taking medicine, and gradually recovers in 3 ~ 4 months.
2. Vitamin AD capsules (concentrated cod liver oil capsules), each time 1 capsule, three times a day. When taking it continuously, you should stop taking it every day according to your condition.
3. Vitamin AD drops (containing vitamin A and vitamin D), the preventive dose is 3 ~ 6 drops per day, and the therapeutic dose is 15 ~ 60 drops per day; It is best to stick to the preventive dose for a period of time after the illness recovers.
4. You can take a mixture of vitamins and trace elements such as 2 1 Jinweita, Jinerkang, Golden Partner or Happy Growth.
food source
Vitamin A only exists in animal foods such as animal liver, egg yolk, milk and fish eggs. Cod liver oil preparation also contains a lot of vitamins A and D. Although there is no vitamin A in plants, carotenoids are contained in yellow-green plants such as carrots, and carotenoids are contained in corn, spinach, pea seedlings, red sweet potatoes, some fruits and peppers, which can be converted into vitamin A in human body. Among them, β -carotene has the highest pre-vitamin A activity.
People in need of compensation
1. Vitamin A in pregnant and lactating women can enhance the antioxidant function of human cells, make skin smooth and improve dryness caused by aging. It is also helpful for the repair of organs and tissues such as uterus and vagina. Therefore, pregnant women should pay attention to vitamin A supplementation.
2. People in a polluted environment When people are in a polluted environment, free radicals are easily generated in the body.
This leads to many diseases and accelerates aging and death. Therefore, compared with ordinary people, more vitamin A is needed to eliminate free radicals and maintain the health and safety of the body.
People who work in front of the computer for a long time should stare at the screen at close range for a long time when using the computer, thus consuming a lot of vitamin A, and paying more attention to taking some vitamin A.
4. Diabetic patients with diabetes can't convert β -carotene into vitamin A smoothly, so they need to supplement vitamin A directly, otherwise it will cause retinal detachment.
5. Vitamin A promotes the development of cells and tissues of developing teenagers and children. Therefore, teenagers and children need to supplement vitamin A regularly to keep healthy growth.
6. Vegetarian vitamin A mostly exists in animal foods. Therefore, vegetarians need to supplement some β -carotene regularly and convert it into vitamin A to maintain the normal needs of the human body.
Supply description
1. Because the digestion and absorption of vitamin A need the participation of minerals and fats, and can be stored in the body, it is not necessary to supplement it every day.
2. If B vitamins, vitamin D and E, calcium, phosphorus and zinc can be taken together, the curative effect will be better.
3. Women who take oral contraceptives should reduce the dose of vitamin A. ..
4. Those who are taking cholesterol-lowering drugs should increase the intake of vitamin A appropriately.
5. Because both vitamin A and β -carotene are easily destroyed by alkali and high temperature, do not add baking soda that can make dishes bright green when cooking. Vegetables rich in carotene, such as broccoli, spinach, carrots, etc., can improve the utilization rate of carotene after moderate cooking, but it is easy to lose carotene after excessive cooking or freezing dehydration, which needs our attention.
6. Vitamins are easily oxidized in the air, or destroyed by ultraviolet radiation, and lose their physiological functions. Therefore, the preparation of vitamin A should be stored in a brown bottle to avoid light.
Excessive injury
Long-term overdose of vitamin A can lead to serious poisoning and even death. Repeated use of vitamin A for several weeks to several years, with the dosage exceeding 10 times of the recommended intake, will cause chronic vitamin A poisoning. Vitamin A poisoning is characterized by fatigue, low fever, hyperhidrosis, nausea, vomiting, loss of appetite, headache, increased intracranial pressure, exophthalmos, diplopia, dry skin, rash, itchy skin, pigmentation, alopecia, joint pain, calcification of tissues around joints, developmental stagnation, hepatosplenomegaly, hypochromic anemia, neutropenia, thrombocytopenia and other symptoms.
In addition, for the fetus, if pregnant women take a large amount of vitamin A in the early pregnancy, the fetus will have anencephaly, eye defects, cleft palate, spina bifida, limb defects and other malformations in the order of organ formation. Taking a large amount of vitamin A in pregnant women can also lead to urinary tract malformation and congenital cataract in the fetus.
Taking a large dose of vitamin A at one time can cause acute poisoning. After a few hours, it will cause symptoms such as irritability, drowsiness, dizziness, delirium, coma, nausea, vomiting, diarrhea, headache, papilla edema, exophthalmos, visual impairment, increased intracranial pressure of infants accompanied by anterior fontanelle swelling, skin erythema, etc., and the symptoms will disappear after several days of drug withdrawal. The results of blood biochemical examination showed that prothrombin was low, hypoproteinemia, serum alkaline phosphatase was high and blood lipid was high.
solution
For chronic vitamin A poisoning, it will take weeks to months to fully return to normal after drug withdrawal and supportive therapy. If it is acute vitamin A poisoning, corticosteroids and vitamin C can reduce its toxic reaction.
Classic cookbook
Cold pea
Ingredients: 200g of peas, 50g of auricularia auricula, 50g of cucumber, 5g of salt 1 g, 5g of garlic slices, 0/0ml of vinegar/kloc-0, 3ml of mustard oil.
Practice: Wash peas, blanch them with hot water and dry them in the air; Soak auricularia auricula, blanch to dry, and cut into shreds; Wash cucumber and cut into strips; Put them in a container, add seasoning and stir well.
Efficacy: promoting blood circulation and detumescence, clearing away heat and toxic materials. It can be used for treating fundus hemorrhage, edema and dysuria.
Characteristic Dutch beans contain vitamin A, the content is 80 micrograms per 100 grams; Auricularia auricula has the function of catharsis and detoxification; Cucumber is crisp and refreshing, which has the effect of promoting fluid production and quenching thirst. This dish is cool and delicious, which can stimulate appetite, especially in hot summer.
Dry frying
Raw materials: 250g pork liver, cucumber 100g, salt and monosodium glutamate 1g, 25ml vegetable oil, 5g garlic slices, shredded ginger and onion, 6ml soy sauce and 4ml cooking wine.
Wash and slice pig liver and cucumber; When the oil is hot, add onion, ginger and garlic, stir-fry until fragrant, add pork liver, add cucumber and other seasonings, and stir-fry for a while.
Has the effects of nourishing blood, softening liver, improving eyesight and clearing heat. Can be used for treating visual impairment, night blindness, insomnia, anemia and other diseases.
Characteristics Pig liver is rich in vitamin A, the content is close to 5000 micrograms per 100 grams. Among all foods containing vitamin A, animal liver ranks first, and pig liver is one of them, and it is easy to buy. Cucumber mainly plays the role of side dishes here, which can enhance the umami taste of dishes and contain a variety of nutrients.
Braised eel in brown sauce
350g of eel, salt and monosodium glutamate 1 g, 25ml of vegetable oil, 5g of soy sauce10ml, 5g of onion and ginger, and cooking wine10ml.
The practice is to clean the eel and cut it into silk; When the oil is 50% hot, add the onion and ginger and stir-fry for a while; Then pour in shredded eel and stir fry; Add seasoning and appropriate amount of water boiling; Add monosodium glutamate when the fish is cooked.
Efficacy: stopping bleeding, tonifying deficiency, benefiting qi and relieving cough. Can be used for treating asthenia, deficiency of qi and blood, cough, etc.
The characteristic eel contains vitamin A, the content is 890 micrograms per 100 grams. Moreover, eel is delicious and tender, and it is a good dish for nourishing and fitness.
Fried shredded pork with carrot
Ingredients: carrot 250g, lean meat 100g, salt and monosodium glutamate 1g, vegetable oil 25ml, shredded ginger with minced garlic 5g, and soy sauce 5ml.
Practice carrots washed and cut into pieces, and lean meat cut into silk; When the oil is 50% hot, add minced garlic and shredded ginger, stir-fry until fragrant, and then stir-fry shredded pork; Then add carrots; Finally, add seasoning and stir-fry the food.
Efficacy tomorrow, liver tonic, cancer prevention. It has therapeutic effect on night blindness, malnutrition, diabetes and other diseases.
Characteristics Carrots are rich in vitamin A, about 688 micrograms per100g, which is rich in vitamin A in plant foods. Lean pork is rich in nutrition, and carrot can promote the absorption of vitamin A.
Stewed Beef with Carrots
Ingredients: carrot 250g, beef 200g, salt and monosodium glutamate 1 g, soy sauce10ml, ginger and garlic 8g, aniseed 5g and vegetable oil 20ml.
Practice cut beef into pieces, soak it in boiling water and remove it; Wash carrots and cut into pieces; Stir-fry ginger, garlic and aniseed for a while, and add beef, other seasonings and appropriate amount of water; Stew the beef until it is 80% cooked, add carrots and stew until cooked.
Efficacy: improving eyesight, nourishing stomach, tonifying kidney and invigorating qi. Can be used for treating vision loss, asthenia, stomach cold, and kidney deficiency.
Characteristic carrots are rich in vitamin A; Beef is warm and sweet, and has the effect of keeping out cold and tonifying deficiency. This dish is delicious, mellow, rich in flavor and rich in nutrition.
Fried pork liver with carrot
Raw materials: carrot 250g, pork liver 200g, salt and monosodium glutamate 1 g, vegetable oil 30ml, shredded ginger10ml, sugar 6g, starch10g, cooking wine10ml.
Wash carrots, cut into pieces like pork liver, and soak pork liver in soy sauce and cooking wine; Stir-fry shredded ginger and carrot slices until they are five ripe, and take them out; Stir-fry pork liver to 80% maturity, add carrot slices and seasoning, continue to stir fry, and thicken with starch when cooked.
Efficacy: improving eyesight, nourishing liver, invigorating spleen and appetizing. It has therapeutic effect on night blindness, dry eye, malnutrition and other diseases.
Characteristic carrots contain a lot of carotene, which can be converted into vitamin A in the body, and pig liver itself also contains a lot of vitamin A. The combination of the two can make people get richer vitamin A. This dish not only has a good effect on preventing and treating eye diseases, but also is rich in various nutrients.
Hot and sour mutton liver
The raw materials are sheep liver 300g, salt 1 g, vegetable oil 20ml, vinegar 20ml, pepper10g, shredded onion, shredded ginger and garlic 5g each, and starch10g.
Practice cut the cooked lamb liver into pieces; Stir-fry shredded onion, shredded ginger, sliced garlic and pepper in oil, and stir-fry in sheep liver; Stir-fry sheep liver, add salt and vinegar, thicken with starch and stir-fry for a while.
Efficacy appetizing tomorrow, promoting blood circulation and nourishing blood. It has therapeutic effect on night blindness, visual impairment, anemia and other diseases.
Characteristics Sheep liver contains vitamin A, the content of which is 20972 micrograms per100g, which is the most abundant in animal liver. This dish is delicious, and it can stimulate the appetite and nourish the liver.
Fried rape with vegetarian dishes
The raw materials are 500g of rape, 50g of mushroom, 2g of salt, 20ml of vegetable oil, 5g of minced garlic and 8g of starch.
Practice washing rape and cutting it into sections; Soak mushrooms, blanch with boiling water, and take them out; Stir-fry rape in hot oil for a while, and add mushrooms and seasonings; After cooking, thicken the vegetables with starch.
Efficacy: promoting blood circulation, lowering blood pressure, invigorating spleen and nourishing stomach. It has therapeutic effect on hypertension, gastritis, blood stasis, constipation and other diseases.
Characteristic rape contains vitamin A, the content is per103g103g. Mushrooms are flat, sweet, smooth and refreshing, and have the functions of stopping bleeding, regulating qi and resisting cancer. This dish is light in taste and elegant in color, which helps to enhance metabolism in the body.
Scrambled Eggs with Chinese Chives
Ingredients: 250g leek, 3 eggs, 2g salt, monosodium glutamate 1g, 5g minced garlic and 20g vegetable oil.
Wash the leeks and cut them into sections; Beat the eggs into a bowl and stir well; Heat oil, pour in egg mixture, stir-fry for a while, add leek and seasoning, and stir-fry until cooked.
Efficacy: promoting blood circulation, removing blood stasis, clearing away heat and toxic materials, and relaxing bowels. It can be used for treating blood stasis, red eyes, sore throat, constipation, etc.
Characteristic leek contains vitamin A, and the content per kloc-0/00g is about 235 micrograms. Eggs are rich in nutrition. But it's best not to eat it raw. This dish is yellow-green, harmonious in color and rich in various nutrients, which helps to improve human immunity.
Fried lettuce in oyster sauce
Ingredients: 500g lettuce, 50g oyster sauce, salt and monosodium glutamate 1 g, 20g vegetable oil.
Practice lettuce washing and cutting into pieces; Stir-fry oyster sauce and lettuce for a while; Add seasoning and the food will taste.
The effects of lowering blood pressure and tonifying kidney, enriching blood and benefiting qi. Can be used for treating hypertension, hematuria, nephropathy and heart disease.
Characteristic lettuce contains provitamin A, which is close to 300 micrograms per100g, and is also rich in vitamin B and various minerals. Oyster sauce also contains a variety of nutrients, has the smell of seafood, and is a delicious condiment. This dish is refreshing and delicious, and it is an indispensable dish in summer diet.
Milk broccoli
Raw materials: broccoli 200g, milk 100g, mushrooms 45g, ham 25g, salt and monosodium glutamate 1g, vegetable oil 25g and sugar 5g.
The practice is to break the broccoli into small pieces and wash it, blanch it with boiling water, remove it and control it; Soak mushrooms and cut into pieces; Stir-fry broccoli and mushrooms in oil for a while; Add ham, milk and various seasonings and stir-fry until cooked.
Efficacy: enriching blood, preventing cancer, moistening lung and relieving cough. Can be used for treating cough, osteoporosis, and deficiency of qi and blood.
Characteristics Broccoli is rich in provitamin A, and the content per 100g is about 1202g, which is relatively high in vegetables. Mushrooms and ham are also very nutritious as side dishes. This dish is delicious in color and light in milk flavor, which is pleasing to the eye.
Sauté ed mushrooms with bracken
400g of bracken, 0/00g of mushroom/kloc-,25g of green pepper, 2g of salt, 33g of vegetable oil, 5g of shredded ginger, 0/0g of starch/kloc-,and 6ml of cooking wine.
Practice bracken and shiitake mushrooms are washed, cut into sections and slices respectively, boiled in boiling water, fished out, and green peppers are shredded; Add bracken, mushrooms, shredded green peppers and various seasonings to 60% hot oil, stir-fry until cooked, and thicken with starch.
Efficacy: clearing away heat and toxic materials, moistening lung and relieving cough, tonifying kidney and strengthening stomach. Can be used for treating vision loss, common cold, cough, constipation and other diseases.
Characteristic Pteridium aquilinum contains provitamin A, the content is about 280 micrograms per 65438 000 grams. In addition, it is rich in vitamin C and various minerals, which can be seen everywhere in barren hills, grasslands and villages. Mushrooms and green peppers play a side dish role and are nutritious. This dish is delicious and light.
Jiaozi stuffed with leek.
Ingredients: 500g leek, 3 eggs, 50g shrimp, 500g flour, 2g salt, 5ml monosodium glutamate 1 g sesame oil, 8g minced garlic, 30ml vegetable oil15ml vinegar.
Practice the noodles, wash and chop the leeks; Stir-fry the eggs, mix well and let them cool; Adding leeks, shrimps and various seasonings, and uniformly stirring to prepare stuffing; Make noodles into dumpling skins and wrap them in jiaozi; Boil in water. You can dip in vinegar.
Efficacy: promoting blood circulation, removing blood stasis, relaxing bowels, nourishing heart and kidney. Can be used for treating anorexia, dyspepsia, palpitation and insomnia, constipation, etc.
Characteristic leek is rich in provitamin A; Eggs and shrimps are rich in nutrition; Flour contains vitamin B 1, which helps to prevent beriberi. Jiaozi is a traditional diet in China, with unique flavor, delicious taste and distinctive dietary characteristics.
Porphyra and shrimp skin soup
Ingredients: 60g laver, 50g shrimp skin, 50g tomato, salt and monosodium glutamate 1g, 5g soy sauce and 4g pepper.
Practice washing tomatoes and cutting them into pieces; Add a proper amount of water to the pot, and add tomatoes after the water boils; Wash laver and shrimp skin and put them into a pot; Add seasoning and stir well.
Has the effects of clearing away heat, lowering blood pressure, tonifying kidney, resisting cancer, calming nerves and strengthening bones. Can be used for treating hypertension, rickets, qi and blood deficiency, neurasthenia, and spleen and stomach weakness.
The characteristic laver contains provitamin A, the content of which is about 228 micrograms per 65438 000 grams. Shrimp skin is rich in nutrition and has the functions of calming nerves, relieving itching and strengthening bones. This soup is delicious, salty with seafood, and it is a common routine drink for people.
Fern cucumber soup
200g bracken, 80g cucumber, salt and monosodium glutamate 1g, 8g starch and 3g pepper.
Practice bracken washing and cutting, cucumber washing and cutting; Add a proper amount of water to the pot, add bracken and cucumber until the water boils, add various seasonings and thicken with starch.
Efficacy: improving eyesight and tranquilizing mind, clearing away heat and toxic materials, promoting fluid production and quenching thirst. It can be used for treating vision loss, dizziness, edema and dysuria.
Pteridium aquilinum contains provitamin A, the content of which is about 280μ g/65438 000g. Cucumber is crisp, sweet and nutritious. This soup is light and delicious, and has the functions of quenching thirst and relieving summer heat, diuresis and detoxification, moistening lung and relieving cough.
Mutton liver japonica rice porridge
The raw materials are sheep liver 1 50g, japonica rice100g, salt and monosodium glutamate1g, and leek powder 25g.
Practice wash the japonica rice, put it in a pot, add some water and boil it; Remove the sheep liver with boiling water, cut it into cubes, wash the leek and cut it into powder; Boil japonica rice until it is six-ripe, and put it into sheep liver; After the porridge is cooked, add seasoning and stir well.
Efficacy: nourishing blood, improving eyesight, nourishing stomach and strengthening spleen. Can be used for treating vision loss, night blindness, spleen and stomach weakness, etc.
Characteristics Sheep liver is rich in vitamin A; Japonica rice is nutritious and can promote digestion. As a condiment, leek adds flavor and color to food. This kind of food is slightly salty, refreshing and delicious, which can stimulate people's appetite, maintain gastrointestinal health, protect eyesight and prevent night blindness.
Fresh mango juice
The raw materials are 500g of mango and 50g of sweet orange.
Practice: Peel and core mango and sweet orange, put them into a juicer, and squeeze out mango sweet orange juice for drinking.
Has the effects of promoting fluid production, quenching thirst, invigorating spleen, regulating stomach, and stimulating appetite. Can be used for treating anorexia, dyspepsia, dizziness and anemia.
Characteristics Mango is rich in vitamin A, with about 1340 micrograms per 100 grams, which is rich in vitamin A in fruits. Sweet orange contains vitamin A (nearly 30 micrograms per100g), vitamin B, vitamin C, vitamin D and other vitamins, which are rich in nutrition. This kind of fruit juice is sweet and sour, which quenches thirst and helps digestion.
Drinking a glass of iced mango sweet orange juice in hot summer can relieve summer heat and help to recover physical strength.