The main functions of vitamin A are as follows: ① It is necessary to maintain the health of all epithelial tissues. When lacking, the epithelial tissue is dry, proliferated and hyperkeratinized, and the ability to resist microbial infection is reduced. For example, the secretion of lacrimal gland epithelium stops, which can make cornea and conjunctiva dry, inflame and even soften perforation. When sebaceous glands and sweat glands are keratinized, the skin is dry and prone to hair follicle papules and hair loss. ② Promote growth, development and reproduction. When vitamin A is lacking, children will suffer from stunted growth, skeletal dysplasia and decreased reproductive function. (3) The composition of photosensitive substances in visual cells. Vitamin A can be oxidized by dehydrogenase to produce retinol, which can combine with different opsins in photoreceptors (rod cells and cone cells) to produce various opsins with different absorption spectra, such as rhodopsin and rhodopsin. Pigment is a photosensitive substance, and its absorption of photons will cause a series of physical and chemical changes, resulting in receptor potential. This receptor potential is transformed into pulsed nerve impulses through various nerve cells in the retina, which are transmitted to the brain to produce vision. It is known that rhodopsin in retina can be continuously decomposed and regenerated and form a dynamic balance during the photosensitive process. When the retinin is in the dark, the retinoic acid in it exists in the form of 1 1- cis, which is called 1 1- cis, but it quickly turns into all-trans retinoic acid after illumination. With the change of configuration, retinol fades and decomposes into trans retinoic acid and retinol. Trans-retinoic acid can be transformed into 1 1- cis-retinoic acid again after low light irradiation, which combines with visual protein to form rhodopsin, thus ensuring that rod cells can continue to be sensitive to light and appear dark vision, that is, they can see the outline and shape of things clearly under low light. However, rhodopsin and retinaldehyde often undergo catabolism, so protein and vitamin A need to be supplemented continuously. If the supply of vitamin A is insufficient, the synthesis of rhodopsin in rod cells will decrease, which will lead to dark vision disorder-night blindness.
① vitamin B 1
B 1 is the earliest purified vitamin. 1896, hickmann, a scientist from the Kingdom of the Netherlands, first discovered that 19 10 was extracted and purified from rice bran by Polish chemist Fonk. White powder, easily soluble in water and easily decomposed in alkali. Its physiological function is to stimulate appetite and maintain normal nerve activity. Without it, it will cause beriberi and neurodermatitis. Adults need to take 2 milligrams a day. It is widely found in rice bran, egg yolk, milk, tomatoes and other foods, and has been artificially synthesized. Because its molecules contain sulfur and amino groups, it is called thiamine, also known as anti-beriberi vitamin. It mainly exists in seed skin and germ, and is the most abundant in rice bran, wheat bran, soybean, yeast, lean meat and other foods. In addition, Chinese cabbage, celery, Chinese medicine Saposhnikovia divaricata and plantain seed are also rich in vitamin B 1. The extracted vitamin B 1 hydrochloride is monoclinic platelets. Vitamin B 1 nitrate is a colorless triclinic crystal with no hygroscopicity. Vitamin B 1 is easily soluble in water and will be lost with water during food cleaning. After heating, B 1 mainly exists in soup. If vegetables are processed too finely, cooked improperly or canned, vitamins will be lost or destroyed in large quantities. Vitamin B 1 is easily destroyed when heated in alkaline solution, but it is thermally stable in acidic solution. Oxidants and reductants can also make it ineffective. Vitamin B 1 is converted into dehydrothiamine (also known as sulfur pigment) after oxidation, which can show blue fluorescence under ultraviolet irradiation. This characteristic can be used to detect and quantify vitamin B 1. Vitamin B 1 is converted into thiamine pyrophosphate (also known as cocarboxylase) in vivo, which participates in the metabolism of sugar in vivo. Therefore, when vitamin B 1 is deficient, the oxidation of sugar in tissues will be affected. It also inhibits cholinesterase activity. When vitamin B 1 is deficient, the activity of this enzyme is too high, and acetylcholine (one of neurotransmitters) is destroyed in large quantities, which affects nerve conduction and can cause gastrointestinal peristalsis, decreased secretion of digestive tract, loss of appetite, indigestion and other obstacles.
② Vitamin B2
B2 is also called riboflavin. Whey was first discovered by Bruce, a chemist from the United Kingdom of Great Britain and Northern Ireland, in 1879. It was extracted from milk by Goldberg, a chemist from the United States of America, and synthesized by Cohen, a German chemist, in 1935. Vitamin B2 is orange-yellow needle-like crystal, slightly bitter in taste, yellow-green fluorescence in aqueous solution, and easy to decompose under alkaline or light conditions This is why you don't need alkali to cook porridge. Without it, the human body is prone to stomatitis, dermatitis, microvascular hyperplasia and so on. Adults should take 2 ~ 4 mg daily, which is rich in cereals, vegetables, milk and fish.
Vitamin B3 is the most needed vitamin among B vitamins. It is not only a vitamin to maintain the health of digestive system, but also an indispensable substance to synthesize sex hormones. For modern people with heavy life pressure, the role of nicotinic acid in maintaining the health of nervous system and the normal operation of brain function can never be ignored.
Recommended daily intake: the recommended daily intake for adults is 13 ~ 19 mg. Pregnant women (pregnant women products, pregnant women information) is 20mg；; 22 mg for lactating women.
Insufficient: pellagra.
Food sources: whole wheat products, brown rice, mung beans, sesame seeds, peanuts, mushrooms, laver, figs, dairy products, eggs, chicken, liver, lean meat, fish and so on.
People in need:
For people who are worried about cholesterol, it is helpful to increase the intake of nicotinic acid;
When the skin (skin care products, skin information) is particularly sensitive to sunlight, it is often an early symptom of niacin deficiency; People with dermatitis, desquamation and rough skin need nicotinic acid;
People who lack vitamins B 1, B 2 and B 6 need extra supplements because they cannot synthesize nicotinic acid from tryptophan.
People who are often nervous and irritable, even those with schizophrenia, are beneficial to supplement vitamin B 3.
Patients with diabetes (diabetes products, diabetes information) and hyperthyroidism also need nicotinic acid.
③ Calcium pantothenate.
B5 is also called pantothenic acid. Anti-stress, anti-cold, anti-infection, prevent the toxicity of some antibiotics, and eliminate postoperative abdominal distension.
④ vitamin B6
Has the effects of inhibiting vomiting and promoting development. Without it, it will cause vomiting, cramps and other symptoms. Include pyridoxine, pyridoxal and pyridoxamine. Pyridoxine is transformed into pyridoxal in vivo, and pyridoxal and pyridoxamine can be transformed into each other. Foods such as yeast, liver, lean meat, grains and cabbage are rich in vitamin B6. Vitamin B6 is easily soluble in water and alcohol and slightly soluble in fat solvents. It is easy to be destroyed when exposed to light and alkali, and it is not resistant to high temperature. Vitamin B6 combines with phosphoric acid in vivo to form pyridoxal phosphate or pyridoxamine phosphate. They are coenzymes of many amino acid metabolizing enzymes, so they are very important for amino acid metabolism.
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.
Vitamin D is the engine that forms bones and cartilage, which can make teeth hard. It is also important for nerves and inhibits inflammation.
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.