Vitamin is a kind of small molecule organic matter necessary to maintain the normal life process of living things. They are in small demand, but they are very important for keeping healthy. Vitamins cannot provide heat energy to the body, nor can they be used as substances that constitute body tissues. Their main function is to regulate the metabolism of the body by being a component of coenzyme. Long-term lack of any vitamin will lead to corresponding diseases (vitamin deficiency).
Vitamins are a group of low molecular weight organic compounds, which are necessary for the normal function of the body, but they cannot be synthesized in the body, or the amount of synthesis is very small, so they must be supplied through food.
Water-soluble vitamins: vitamin B (B 1, B2, pantothenic acid, vitamins PP, B6, biotin, folic acid, B 12), vitamin C, etc.
Fat-soluble vitamins: vitamins A, D, E, K, etc.
Reasons for vitamin deficiency:
6? 1 Insufficient food intake: partial eclipse, unreasonable dietary distribution and reduced intake;
6? 1 absorption disorder: gastrointestinal and hepatobiliary diseases, and the utilization rate is reduced;
6? The demand for 1 has increased: growing children, pregnant women and lactating women;
6? 1 take some drugs: normal intestinal bacteria can synthesize vitK, vitB6, vitPP, biotin, pantothenic acid and folic acid, and long-term use of antibiotics can inhibit bacteria from synthesizing antibiotics;
6? 1 Specific defects of the body: lack of endogenous factors affects the absorption of vitB 12, and chronic liver and kidney diseases prevent vitD from being hydroxylated into active vitD, resulting in vitD deficiency.
Fat-soluble vitamin
6? 1 *** Same function:
1. including a, d, e, k;
2. Insoluble in water, only soluble in fat and lipid solvents;
3. Lipophily, which exists with lipids in food and is absorbed with the absorption of lipids. When lipids are poorly absorbed, the absorption of fat-soluble vitamins is also reduced, and even diseases are caused;
4. Absorbed fat-soluble vitamins are transported in the blood by specific binding with lipoprotein and some special binding proteins, and can also be stored in the body, especially in the liver. So eating too much is prone to poisoning symptoms.
I. Vitamin A
(Also known as: retinol, anti-dry eye vitamin)
(1) Source
1. Animal food: liver and cod liver oil.
2, plant food: can be converted into vitamin A.
Carotenoid provitamin a
(3) Biochemical action
1, which constitutes the photosensitive substance in visual cells (1 1- cis retinoic acid, all-trans retinoic acid).
2. Participate in the synthesis of glycoprotein
3. Other functions
Maintain the integrity of epithelial tissue structure and function.
Maintain the growth and development of the body.
shortcomings
1, night blindness (passerine) has insufficient rhodopsin, and its adaptability to dark light is weakened, leading to night blindness.
2, dry eye long-term lack of vitamin A can lead to dry eye (conjunctivitis) caused by lacrimal gland secretion disorder.
3. Growth stagnation and infertility.
Excessive intake
Headache, nausea and diarrhea, hepatosplenomegaly
Pregnant women: fetal malformation
Second, vitamin D.
(Also known as: anti-rickets vitamin, calciferol)
(1) Source
Animal food: liver, milk, egg yolk, cod liver oil.
2. 7- dehydrocholesterol in skin microvessels can be converted into vitamin D3 by sunlight.
(3) Biochemical action
1, promoting the absorption of calcium and phosphorus in intestine.
2. Promote the reabsorption of calcium and phosphorus by renal tubules.
3. Increase the concentration of blood calcium and phosphorus, and promote bone calcification.
shortcomings
Children: rickets adults: rickets and osteoporosis
Third, vitamin E.
(1) Source:
Wheat germ oil, cottonseed oil, peanut oil and other plant seeds.
(2) Chemical essence:
Vitamin E is also called tocopherol and anti-infertility vitamin.
Anaerobic: thermal stability
Aerobic: easy to self-oxidize (can protect other substances)
(3) Biochemical action
1, antioxidant effect.
2. Anti-animal infertility.
3. Promote heme synthesis.
shortcomings
1, fewer red blood cells and shorter life span.
2. The brittleness of red blood cells increases.
3, neurological disorders (rare).
Excessive intake of vitamin e is non-toxic.
Four. Vitamin k
(1) Source
K 1 mainly exists in the livers of animals and plants, and K2 is the product of human intestinal bacterial metabolism. K3 and K4 used in clinic are synthetic.
(2) Chemical essence
(3) Biochemical action
As an auxiliary factor of glutamate carboxylase, it promotes the synthesis of prothrombin and coagulation factors Ⅱ, ⅶ, ⅸ and ⅹ, and participates in coagulation.
shortcomings
Coagulation factor synthesis disorder, prolonged coagulation time, easy to bleed, especially newborn babies are prone to hemorrhagic diseases.
Newborn babies are sterile in the intestines, unable to synthesize vitamin K, and have no storage in the body itself, so they are prone to bleeding due to vitamin K deficiency, so the content of vitamin K in the mother should be increased before birth.
the second part
water-soluble vitamin
* * * Same function
* Soluble in water, so it is easy to excrete with urine.
* It is not easy to store in the body and must be taken from food frequently.
kind
B vitamins and vitamin c
I vitamin B 1
(1) Source
Seed husk and germ, soybean, yeast and lean meat.
(2) Chemical essence
Also known as anti-beriberi vitamin, it is also called thiamine because its molecules contain sulfur and amino groups.
biochemistry
1 participates in the catabolism of sugar in the form of coenzyme. As a coenzyme of pyruvate dehydrogenase system and α -ketoglutarate dehydrogenase system, it participates in oxidative decarboxylation of α -keto acid.
2. As a coenzyme of transketolase, it participates in pentose phosphate metabolic pathway.
3.TPP can inhibit the activity of cholinesterase and participate in the synthesis of acetylcholine.
(5) Deficiencies:
1, beriberi: peripheral neuritis such as weakness of limbs, muscle numbness and abnormal sensation.
2, indigestion: gastrointestinal peristalsis slowed down, digestive juice secretion decreased, loss of appetite.
3. Peripheral neuritis.
Second, vitamin B2.
(1) Source:
Yeast, eggs, milk and green leafy vegetables.
(2) Chemical essence
Vitamin B2 is the condensation product of nucleolar alcohol and 6,7-dimethylisoalloxazine. It is a yellow needle-like crystal, soluble in water, also called riboflavin.
(5) No disease:
Long-term lack of vitamin B2 in diet, proliferation of blood vessels in cornea and corners of mouth, causing cataract, keratitis, glossitis and bursitis.
6? Daily requirement per person 1 vitamin B2: 0.6 mg for children and 0.6 mg for adults.
Third, vitamin PP
(1) Source
Meat, liver, grains, peanuts. In addition, the human body can use tryptophan to synthesize vitamin PP.
(5) insufficient
Bark pustule
Manifestations: symmetrical dermatitis, diarrhea, nerve injury and mental disorder (dementia).
Fourth, vitamin B6.
(1) Source
Animal and plant food. Intestinal bacteria can also synthesize some vitamin B6.
(5) insufficient
1, γ -aminobutyric acid synthesis disorder, overexcitation, allergies and even convulsions.
2, low hemoglobin, small cell anemia and increased serum iron.
3. Long-term use of isoniazid requires vitamin B6 supplementation.
acid regurgitatio
(1) Source
Animal food, cereals and bean products
(5) insufficient
The lipid in animal liver increases, the oxidative decarboxylation of pyruvate is blocked, the growth is slow, and reproductive disorders appear.
Seven. folic acid
(1) Source
Folic acid can also be synthesized by green vegetables, yeast, animal liver, kidney and intestinal bacteria.
(5) insufficient
Nucleic acid synthesis disorder, animal growth stagnation, red blood cell development and maturation disorder, megaloblastic anemia
VIII. Vitamin B 12
(1) Source
Animal food: meat, liver.
(2) Chemical essence:
Also known as cobalamin, it is the only vitamin containing metal elements. There are three forms of naturally occurring B 12: 5'- deoxyadenosine cobalamin, methylcobalamin and hydroxycobalamin.
(5) insufficient
Macrocytic anemia
Overview of B vitamins
1, intestinal synthesis: B2, PP, B6, pantothenic acid, folic acid, biotin, B 12.
2. Biotin and B 12 are directly used as coenzymes.
3. Metal-containing coenzyme: B 12.
4. Store in the liver: B 12
Nine, vitamin C.
(1) Source
Fresh fruits and vegetables
(5) insufficient
contemptible
Capillaries are prone to bleeding, and teeth and bones are underdeveloped or degenerated.
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