Useful, that is, the physiological function of vitamin C is on the high side. Vitamin C, also called L- ascorbic acid, is a water-soluble vitamin, which can treat scurvy and is acidic, so it is called ascorbic acid. It is rich in lemon juice, green plants and tomatoes. Ascorbic acid is monoclinic or needle-like crystal, which is easy to be oxidized to produce dehydrogenated bad blood acid, and still has the function of vitamin C. In alkaline solution, the lactone ring in dehydrogenated bad blood acid molecule is easy to be hydrolyzed to diketone gulonic acid. This compound can't change into lactone structure in animals. Oxalic acid or sulfate is combined with sulfuric acid, which is finally produced in human body and excreted from urine. Therefore, diketone gulonic acid no longer has physiological activity. Norwegian chemist holst found it in lemon juice on 1907. 1934 to obtain pure product, which can be synthesized artificially now. Vitamin C is the most unstable vitamin. Because vitamin C is easily oxidized, it will be destroyed during food storage or cooking, even when chopping fresh vegetables. Trace amounts of copper and iron ions can accelerate the destruction. Therefore, only fresh vegetables, fruits or raw vegetables are rich sources of vitamin C, which is colorless crystal with melting point of 190 ~ 192℃ and is easily soluble in water. The aqueous solution is acidic, has strong chemical activity and is easily decomposed by heat, alkali and heavy metal ions. Therefore, copper pots are not allowed, and the heating time is too long. Plants and most animals can synthesize vitamin C in their own bodies. However, humans, primates and guinea pigs can't synthesize vitamin C, because they lack enzymes to convert L- gulonic acid into vitamin C, so they must take it from food. If vitamin C is lacking in food, scurvy will occur. At this time, there are symptoms such as bleeding, loose teeth, difficult wound healing and easy fracture due to interstitial generation disorder. Because vitamin C has a long half-life in human body (about 16 days), scurvy will only appear after eating food without vitamin C for 3 ~ 4 months. Because vitamin C is easy to be oxidized and reduced, it is generally believed that its natural function should be related to this characteristic. Vitamin C is directly related to the normal synthesis of collagen, tyrosine metabolism and iron absorption. The main function of vitamin C is to help the human body complete the redox reaction and improve the sterilization and detoxification ability of the human body. Long-term lack of vitamin C can lead to scurvy. Eating more fruits and vegetables can meet the human body's demand for vitamin C. Vitamin C plays an important role in promoting the firmness of brain cell structure, preventing the relaxation and contraction of brain cell structure, and preventing the nerve tubules that transport nutrients from being blocked, thinned and relaxed. Taking enough vitamin C can improve the permeability of neural tubules, make the brain get nutritional supplements in time and smoothly, and thus improve brain power and intelligence. According to Nobel Prize winner Pauling, taking large doses of vitamin C has a certain effect on preventing colds and fighting cancer. However, it has been suggested that vitamin C can promote the production of free radicals in the presence of ferrous ions (Fe2+), so it is not safe to use it in large quantities. Daily requirement: Adults need to take 50 ~ 100 mg every day. That is, guava half, pepper 75g, cauliflower 90g, kiwi fruit 2, strawberry 150g, grapefruit 1 piece, papaya half, fennel 125g, cauliflower 150g and orange juice 200ml. Efficacy: Vitamin C can capture free radicals and prevent diseases such as cancer, arteriosclerosis and rheumatism. In addition, it can enhance immunity and is good for skin, gums and nerves. Side effects: So far, vitamin C is considered harmless, because the kidney can excrete excess vitamin C. A newly published research report in the United States pointed out that there is a large amount of vitamin C circulating in the body, which is not conducive to wound healing. Daily intake of vitamin C exceeding 1000 mg will lead to diarrhea, infertility in kidney calculi and even genetic defects. Adverse reactions of taking vitamin C According to the research at home and abroad, with the increase of the dosage of vitamin C, there are more and more adverse reactions. Diarrhea. Taking1~ 4g of vitamin C every day can accelerate small intestine peristalsis and cause abdominal pain and diarrhea. Gastric bleeding. Long-term oral administration of vitamin C can cause nausea and vomiting. At the same time, due to the increase of gastric acid secretion, it can aggravate the pain of gastric and duodenal ulcers, and in severe cases, it can also lead to gastric mucosal congestion and edema, leading to gastric bleeding. Stone. After a large amount of vitamin C enters the human body, most of it is metabolized by the liver, and the final product is oxalic acid, which is excreted from the urine to become oxalate; Studies have found that taking 4 grams of vitamin C orally every day, the content of oxalate in urine will surge from 58 mg to 620 mg within 24 hours. If you continue to take it, oxalate will continue to increase, and it is easy to form urinary calculi. Gout. Gout is a disease caused by the disorder of purine metabolism in the body, which is mainly manifested by the high concentration of uric acid in the blood, leading to a series of symptoms in joints, connective tissues and kidneys. Taking a large amount of vitamin C will lead to a sharp increase in uric acid and induce gout. Infant dependence. Pregnant women take a lot of vitamin C continuously, which will make the fetus dependent on drugs. After birth, if you don't give your baby a lot of vitamin C supplements, scurvy may occur, such as listlessness, gingival swelling and bleeding, subcutaneous bleeding, etc. There are even symptoms such as gastrointestinal bleeding and urinary tract bleeding. Orthopedic diseases in children. Children who take a lot of vitamin C will suffer from orthopedic diseases with a high incidence. Infertility. Women of childbearing age take a large amount of vitamin C for a long time (such as when the daily dose exceeds 2 grams), which will reduce their fertility. Immunity is reduced. Taking a large amount of vitamin C for a long time will reduce the phagocytosis of white blood cells and reduce the body's disease resistance. Allergic reaction. The main manifestations are rash, nausea and vomiting. In severe cases, anaphylactic shock may occur and cannot be abused. Physiological Function of Vitamin E Vitamin E, also known as tocopherol, is a fat-soluble vitamin, which mainly exists in vegetables and beans and is the most abundant in wheat germ oil. There are 8 kinds of naturally occurring vitamin E, all of which are derivatives of benzodihydropyran. According to its chemical structure, it can be divided into tocopherol and tocotrienols (Figure 12), and each class can be divided into four types according to the number and position of methyl groups. α-tocopherol has the highest physiological activity among commercially available vitamin E, while the physiological activities of β-tocopherol, γ-tocopherol and α-triene tocopherol are only 40%, 8% and 20% of α-tocopherol. Vitamin E is a slightly viscous light yellow oil, which is relatively stable under oxygen-free conditions and will not be destroyed even if it is heated above 200℃. However, in the air, vitamin E is easily oxidized and its color becomes darker. Vitamin E is easily oxidized, so it can protect other substances that are easily oxidized (such as vitamin A and unsaturated fatty acids) from being destroyed. Vitamin E in food is mainly absorbed in the upper small intestine of animals, and is mainly carried by β -lipoprotein in blood and transported to various tissues. Isotope tracing experiments show that α -tocopherol can be oxidized into α -tocoquinone in tissues. The latter can combine with glucuronic acid in the liver, enter the intestine with bile, be reduced to α-reproductive hydroquinone, and then be excreted through feces. The metabolism of other vitamin E is similar to that of α-tocopherol. Vitamin e is necessary for animal reproduction. When vitamin E is deficient, the testis of male rats degenerates and normal sperm cannot be formed. Female mouse embryos and placenta atrophy and are absorbed, which will cause abortion. Lack of vitamin E in animals may also lead to muscle atrophy, anemia, encephalomalacia and other neurodegenerative diseases. If accompanied by protein deficiency, it will cause acute liver cirrhosis. Although the metabolic mechanism of these diseases has not been fully clarified, the multiple functions of vitamin E may be related to its antioxidant effect. The symptoms of some human diseases are similar to those of animals lacking vitamin E. Because the content of vitamin E in general food is still sufficient and easy to be absorbed, vitamin E deficiency is not easy to occur, and it is only seen in the absorption of lipids in the intestine. Vitamin E is widely used in clinic, and it has been found that it can prevent and treat some diseases, such as atherosclerosis, muscular dystrophy, brain edema, male and female infertility, threatened abortion and so on. In recent years, vitamin E has been used to prevent aging. Vitamin E was discovered by American chemist Evans in 1922 and extracted from malt oil. It was synthesized artificially in the 1940s. 1960 China has been ready for mass production. It is odorless and tasteless liquid, insoluble in water and soluble in organic solvents such as ether. Its chemical properties are stable, heat-resistant, acid-resistant and alkali-resistant, but it is easy to be destroyed by ultraviolet rays, so it should be kept in a brown bottle. Vitamin E is an excellent antioxidant in human body. Without it, both men and women can't have children, and in severe cases, their muscles will atrophy and their nerves will be numb. Vitamin E is widely found in meat, vegetables and vegetable oils. Under normal circumstances, there is no shortage of people. Daily requirement: The daily requirement of vitamin E for adults is not clear, but the results of animal experiments show that 50 mg of food per day can meet the needs. The demand for pregnancy and breastfeeding has increased slightly. Four spoonfuls of sunflower seed oil, 100 mg of olive oil, 100 g of peanuts or 30 g of almonds and 70 g of walnuts contain vitamin e needed for one day. Efficacy: Vitamin E can resist the invasion of free radicals and prevent myocardial infarction caused by cancer. In addition, it also participates in the formation of antibodies and is a true "descendant supporter". It promotes men to produce energetic sperm. Vitamin E is a strong antioxidant, and insufficient supply of vitamin E will cause various mental or emotional disorders. Wheat germ, cottonseed oil, soybean oil, sesame oil, corn oil, peas, sweet potatoes, eggs and butter are rich in vitamin E. Side effects: taking 200 mg of vitamin E every day will cause nausea, muscle atrophy, headache and fatigue. Taking more than 300 mg of vitamin E every day can lead to high blood pressure, delayed wound healing and limited thyroid function.