Classification: Various vitamins can be divided into two categories:
One: water-soluble vitamins:
Include vitamin B 1 (thiamine), vitamin B2 (riboflavin), vitamin PP (nicotinic acid and nicotinamide), vitamin B6 pyridoxal (alcohol, amine), vitamin B 12 (cobalamin), pantothenic acid, biotin, folic acid, lipoic acid and vitamin C.
Two: fat-soluble vitamins:
Include vitamin a, vitamin d, vitamin e and vitamin K.
The role of various vitamins:
A, fat-soluble vitamins:
1, vitamin a:
Vitamin A, also known as retinol, includes vitamin A 1 and vitamin A2. Vitamin A 1 mainly exists in the liver of mammals and saltwater fish; A2 mainly exists in the liver of freshwater fish.
Vitamin A is the component that constitutes the photosensitive substance in visual cells. Vitamin A can also stimulate RNA synthesis in many tissues. In addition, when vitamin A is deficient, the immune function of the body will be reduced.
When vitamin A is deficient, it will reduce the sensitivity to low light, weaken the adaptability to sunlight, and in severe cases, night blindness will occur. Moreover, vitamin A is also necessary to maintain the structure and function of epithelial tissue. When lacking, it can cause epithelial tissue drying, proliferation and keratinization.
2, vitamin D:
The main sources of vitamin D in food are: cod liver oil, egg yolk, milk, liver, kidney, skin tissue and so on, all of which are rich in vitamin D, and cod liver oil is the most abundant. Vitamin D in dietary form is mainly absorbed with the help of bile salts in the small intestine.
The main function of vitamin D is to promote the absorption and regulate the metabolism of calcium and phosphorus, which is beneficial to bone formation and calcification. Vitamin D can prevent rickets, rickets and hand-foot convulsions (note that calcium should be supplemented first when using vitamin D). Therefore, when vitamin D is lacking, rickets can occur in children and rickets can occur in adults.
3. Vitamin E:
Because vitamin E is related to animal fertility, it is called tocopherol, which mainly exists in vegetable oil, especially soybean oil, corn oil, wheat germ oil and sunflower seed oil.
Vitamin E has antioxidant activity, which can prevent unsaturated fatty acids from automatically oxidizing, protect cell membrane, prolong cell life, and protect the activity of intracellular sulfhydryl enzyme. It is the most important oxidant in the body.
Vitamin E is related to the reproductive function of animals. When animals lack vitamin E, their reproductive organs are damaged or even infertile. Vitamin E is commonly used in clinic to treat threatened abortion and habitual abortion.
Physiological functions of vitamin E include: anti-reproductive infertility, muscular atrophy, anemia and abnormal blood cell morphology.
Vitamin E is generally not easy to be deficient. The mass concentration of vitamin E in normal plasma is 0.9-1.6 mg100 ml, and if it is lower than 0.5mg/ 100ml, vitamin E deficiency can occur.
4, vitamin K:
Vitamin K includes K 1, K2, K3 and K4, in which K 1 and K2 are natural vitamins. At present, vitamin K3 is the most commonly used in clinic. Its main sources include: synthesis of food and intestinal microorganisms, green vegetables, animal liver, soybeans, milk, lactic acid bacteria and Escherichia coli.
The main function of vitamin K is to promote the synthesis of prothrombin in the liver to promote blood coagulation. It plays an important role in blood coagulation. When vitamin K is lacking, some coagulation factors in blood will be reduced, which will lead to prolonged coagulation time and even muscle and gastrointestinal bleeding.
However, because vitamin K is abundant in natural green plants, and the Escherichia coli in the gastrointestinal tract of human body can also synthesize vitamin K, under normal circumstances, the human body will not lack vitamin K.
Second, water-soluble vitamins:
1, vitamin B 1:
Vitamin B 1, also known as thiamine, is an anti-neuritis vitamin (also known as anti-beriberi vitamin). Its main sources are the germ and cortex of lean meat, yeast and cereals. Vitamin B 1 is heat-resistant, and it will not be destroyed even when heated to 120℃.
When vitamin B 1 is deficient, it will hinder the body's glucose metabolism, lead to the accumulation of pyruvate, increase the content of pyruvate in patients' blood, urine and brain tissue, and cause symptoms such as multiple neuritis, skin numbness, heart failure, muscle atrophy, limb weakness and edema of lower limbs, which is called beriberi clinically. According to the research, vitamin B 1 deficiency can also cause gastrointestinal peristalsis to slow down, and the secretion of digestive juice to decrease, leading to symptoms such as loss of appetite and indigestion.
(Vitamin B 1 is very soluble in water, so it is not advisable to wash rice too much to avoid loss.)
2, vitamin PP:
Also known as anti-furuncle vitamin. It is widely distributed in nature, with the most abundant content in yeast, peanuts, cereals, meat and animal liver, and tryptophan can be converted into vitamin PP in the body.
Function: It plays an important role in various enzymatic oxidation-reduction reactions in the body and forms coenzyme with other substances, which plays an important role in metabolism.
3, vitamin B2:
Also known as riboflavin. It is easy to cause oxidation-reduction reaction in vivo, which has two types: oxidation type and reduction type, so it plays a role in transferring hydrogen in the oxidation-reduction process in vivo. It widely exists in animals and plants, and is abundant in animal liver, yeast, soybean and rice bran.
4. Pantothenic acid:
Also known as pantothenic acid, it exists widely in the biological world and is the most abundant in yeast, liver, kidney, eggs, rice bran, wheat, peanuts and peas. It is widely used as an important auxiliary drug for various diseases.
The main active form of pantothenic acid is coenzyme A, which plays an important role in sugar metabolism, lipid catabolism, amino acid metabolism and the synthesis of some important substances in the body.
5, vitamin B6:
Vitamin B6 is widely distributed in animals and plants, especially in grains. At the same time, intestinal bacteria can also synthesize vitamin B6, so vitamin B6 deficiency rarely occurs in human body.
(This article focuses on popular science. If the functional explanation of vitamin B6 or some other vitamins involves too much professional knowledge, it will not be elaborated here.)
6, vitamin B 12:
Vitamin B 12 is widely derived from animal foods, especially in meat and liver. It can also be synthesized in the intestines of humans and animals, so it will not be lacking in general. Vitamin B 12 deficiency is more common in patients with gastrointestinal diseases or after gastrectomy (vitamin B 12 needs to be combined with the internal factors secreted by gastric parietal cells to be absorbed).
Vitamin B 12 is involved in DNA synthesis, which is also important for the maturation of red blood cells. When vitamin B 12 is lacking, pernicious anemia is easily caused.
7. Biotin:
It is rich in sources, such as liver, kidney, egg yolk, yeast, vegetables and cereals. Autogut bacteria can also be synthesized. Therefore, there is generally little shortage.
However, if a large amount of raw egg white is eaten, it can cause biotin deficiency (reason: fresh eggs contain avidin, which can combine with biotin to form a substance that is inactive and difficult to digest and absorb, but the protein of eggs can be destroyed after heating). In addition, taking antibiotics for a long time can inhibit intestinal flora and cause biotin deficiency.
8. Folic acid:
Folic acid widely exists in liver, yeast and vegetables, and can also be synthesized by human intestinal bacteria, so it is generally not easy to be deficient.
Folic acid is related to the synthesis of nucleic acid. When folic acid is deficient, DNA synthesis is inhibited, DNA synthesis in bone marrow megalobocytes decreases, cell division speed decreases, and cell volume increases, so this kind of cell is called megalobocyte, and most of this kind of red blood cells have been destroyed before they mature in bone marrow, resulting in anemia (called megaloblastic anemia). Therefore, folic acid can be used to treat megaloblastic anemia in clinic.
9, lipoic acid:
Lipoic acid is widely distributed in nature, especially in liver and yeast. Lipoic acid and vitamin B 1 coexist in food.
10, vitamin c:
It is also called ascorbic acid because of its function of preventing and treating scurvy. Vitamin C is widely distributed in animals and plants. Only a few vertebrates-humans and other primates, guinea pigs, some birds and some fish-can't synthesize it by themselves, but must get it from food.
Function: 1), ascorbic acid is a strong reducing agent, which participates in many redox reactions in organisms. 2) Vitamin C has the function of preventing anemia, and can also prevent the toxic effects of some transported metal ions. 3) Vitamin C can stimulate the immune system and prevent and treat infection. 4) Vitamin C can prevent the accumulation of histamine and improve allergic reaction.
When vitamin C is deficient, scurvy, capillary fragility, gingival inflammation and bleeding will occur.
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