The catalysis of enzymes is closely related. Coenzymes must participate in the activity of enzymes. It is known that many vitamins are coenzymes of enzymes or constituent molecules of coenzymes.
Therefore, vitamins are important substances to maintain and regulate the normal metabolism of the body. It can be considered that vitamins exist in human tissues in the form of "bioactive substances".
Most vitamins cannot be synthesized in the human body, or the amount of synthesis is insufficient to meet the needs of the human body. Therefore, it must be taken from food. Vitamin content in food
Less, the human body's demand is not much, but it is an indispensable substance. If there is a lack of vitamins in the diet, it will cause metabolic disorders in the human body, resulting in vitamin deficiency.
If vitamin A is lacking, night blindness, dry eye and dry skin will appear;
Lack of vitamin d can cause rickets;
Lack of vitamin B 1 can cause beriberi;
Lack of vitamin B2 can lead to cheilitis, angular stomatitis, glossitis and bursitis;
Lack of PP can cause furuncle;
Lack of vitamin B 12 can lead to pernicious anemia;
Lack of vitamin c can lead to scurvy.
Vitamins are a huge family, and there are dozens of vitamins known at present, which can be roughly divided into two categories: (fat-soluble) and (water-soluble).
The former includes vitamins A, D, E and K, while the latter includes vitamin B and vitamin C, as well as many "vitamins".
The vitamins found in medicine now mainly include:
Fat-soluble vitamin
Vitamin a: maintain normal vision and prevent night blindness; Maintain the health of epithelial cells; Promote growth and development; Increase resistance to infectious diseases;
Prevention and treatment of dry eye.
Vitamin D: regulates the metabolism of calcium and phosphorus in human body, promotes absorption and utilization, and promotes bone growth.
Vitamin e: maintain normal reproductive capacity and normal muscle metabolism; Maintain the integrity of the central nervous system and vascular system.
Vitamin k: stop bleeding. It is not only the main component of prothrombin, but also can promote the liver to produce prothrombin. Vitamin k deficiency in children
water-soluble vitamin
Vitamin B 1: Maintain normal functions of circulation, digestion, nerves and muscles; Adjust the function of gastrointestinal tract; Coenzymes that form decarboxylases participate in sugar metabolism; Can prevent beriberi.
Vitamin B2: Also called riboflavin. Nucleocandin is a component of many important coenzymes in the body. These enzymes can transfer hydrogen during the metabolism of substances in the body. It is also protein.
Substances necessary for sugar and fatty acid metabolism and energy utilization and composition. Can promote growth and development, and protect the health of eyes and skin.
Pantothenic acid (calcium pantothenate): anti-stress, anti-cold, anti-infection, preventing the toxicity of some antibiotics, and eliminating postoperative abdominal distension.
Vitamin B6: It plays an important role in protein's metabolism. Treat neurasthenia, vertigo, atherosclerosis, etc.
Vitamin B 12. Anti-fatty liver, promote the storage of vitamin A in the liver; Promote cell development and maturation and body metabolism; Treat pernicious anemia.
Vitamin B 13 (lactic acid clear).
Vitamin B 15 (alanine). It is mainly used to resist fatty liver and improve the oxygen metabolism rate of tissues. Sometimes it is used to treat coronary heart disease and chronic alcoholism.
Vitamin B 17. Highly toxic. Some people think it can control and prevent cancer. P-aminobenzoic acid. Among the B vitamins, it is one of the newly discovered vitamins.
It can be synthesized in human body.
Inositol: One of the B vitamins, and it is a lipophilic vitamin like choline.
Vitamin c: connecting bones, teeth and connective tissue structures; It has adhesion function to the cells of capillary wall; Increase antibodies and enhance resistance; Promote red blood cell maturation.
Vitamin P: Vitamin PP (nicotinic acid). It plays a role in transferring hydrogen in the process of cell physiological oxidation and has the effect of preventing and treating furuncle.
Folic acid (vitamin M): anti-anemia; Maintain the normal growth of cells and the function of immune system.
Vitamin T: Helps blood coagulation and platelet formation.
Vitamin U: It plays an important role in treating ulcers.
Vitamins are organic compounds needed for human nutrition and growth. If the body lacks vitamins, there will be some kind of disease. Therefore, some people think that vitamins are nutrients.
Entering is "the more the better". The more vitamins people need, the better? The answer is no. The key to reasonable nutrition lies in "moderation". Excessive intake of certain vitamins is not good for your health.
Not only useless, but harmful.
As we know, vitamins can be roughly divided into water-soluble (vitamins B and C) and fat-soluble (vitamins A, D, K, etc.). The excess of water-soluble vitamins can generally follow urine.
The liquid is excreted, and the fat-soluble vitamins A or D cannot be excreted. This gives people the impression that it is harmless to eat too much water-soluble vitamins. Some people argue that.
Take 3-5g of vitamin C orally every day to achieve the purpose of health care. In fact, this is harmful. Experiments have confirmed that taking vitamin C 1 g or more for a long time can cause oxaluria and high uric acid.
Blood disease, hyperemia. Some people may have rash, edema, blood pressure drop and nausea all over their bodies. Among fat-soluble vitamins, vitamin A and vitamin D are caused by taking too much.
Poisoning is the most common. Excessive vitamin A will cause insomnia, asthma, dizziness, alopecia, nausea and diarrhea. Excessive vitamin D can cause loss of appetite, burnout,
Constipation, weight loss and low fever.
Normal people need vitamin C 50-100 mg, vitamin A 2500-3000 international units and vitamin D 300-400 international units every day.
In terms of nutrition, the so-called vitamins should be indispensable for the normal metabolic process and the regulation of physiological functions because the human body can't synthesize them (or the amount of synthesis can't meet the needs).
A kind of substance. They are nutrients that must be supplied by food. Therefore, when it is lacking, some typical clinical symptoms will appear. So far, it has not been found that due to lack of bitter almonds
Glycosides and suffer from any deficiency, so these two substances can not be called vitamins at all.
Vitamin B 15 and vitamin B 17 are food ingredients that are beneficial to human health and are named vitamins by some foreign nutritionists, but they have not been recognized by scholars all over the world so far.
Recognized.
Recent studies have shown that vitamins have some special functions, such as the emotional regulation of pantothenic acid, the reduction of DNA loss by folic acid and vitamin B 12, and folic acid plus B6.
Good for cardiovascular and so on.
For vitamin supplement, we should supplement it from two aspects: diet and vitamin preparation. Fruits and vegetables have high vitamin content, but because of the vitamin content of each vegetable and fruit,
Are different, may not be able to balance vitamin supplements in all aspects, vegetables and fruits in the processing, cooking vitamins are also lost, vitamin preparations can play a balanced role.
However, vitamin preparations are not easy to absorb and are not natural and green, so they are mainly supplemented by fruits and vegetables.
Precautions when taking vitamins ||| Misunderstanding of vitamins||| Common vitamin preparations||| Vitamin adjuvant therapy||| Vitamins and children's health related reference: vitamins.
And health column (columnist: Lin Fanshun) carotene.
References:
How do vitamins work?
If we think of the human body as the engine of a car, vitamins are like pistons. This amazing substance is very small in food, what effect does it have on human body?
Vitamins normalize human metabolism through enzyme system. As long as a vitamin is lacking, it may endanger the whole body.
Vitamins are the constituent elements of human enzyme system. This enzyme system is just like the ignition device of a piston-adjusting the condition of the body, making all parts work effectively and promoting the human body's health
Normal metabolism, normalizing the whole body.
Compared with protein, fat, carbohydrates and other nutrients, the intake of vitamins (even for therapeutic purposes) is very small.
Yes. However, as long as any vitamin is lacking, it may lead to a dangerous state of the whole body.
The main causes of vitamin deficiency are:
① The content in the diet is insufficient. Because of poverty, monotonous diet and partial eclipse, the intake of vitamins in the diet can not meet the needs of the body;
② Dysabsorption in the body. For example, accelerated intestinal peristalsis, reduced absorption area and long-term diarrhea reduce the absorption and storage of vitamins;
③ Increased discharge. It can be excreted by breastfeeding, sweating a lot, and using diuretics for a long time.
(4) accelerated destruction of vitamins in the body due to drugs and other effects;
⑤ physiological and pathological requirements increased;
⑥ Unreasonable food processing and cooking causes a large number of vitamins to be destroyed or lost.
Measures to prevent vitamin deficiency:
① provide a balanced diet;
② Adjust the vitamin supply in time according to the physiological and pathological conditions of human body;
③ Timely treatment of intestinal diseases affecting vitamin absorption;
④ Food processing and cooking should be reasonable to minimize the loss of vitamins.
Fat-soluble vitamins, including A, D, E and K, coexist with lipids in food, and are also related to lipid absorption during intestinal absorption, so the excretion efficiency is low, so when ingested too much,
Can accumulate in the body, produce harmful effects, and even poisoning. Water-soluble vitamins include ascorbic acid (VC) of B vitamins (B 1, B2, B6, B 12, PP, etc.).
Characteristics of water-soluble vitamins:
① Soluble in water, insoluble in fat and organic solvents;
② It is easy to be excreted from urine, and the excretion efficiency is high, so eating in large quantities generally does not produce accumulation and toxic effects;
③ Most of them participate in various enzyme systems in the form of coenzymes or auxiliary groups, which play an extremely important role in many links of intermediate metabolism;
④ Most of the nutritional levels in the body can be reflected in blood and urine.
I. Vitamin A(VA) and Provitamin A (carotenoid)
Vitamin A(retinol), also known as retinol, is as stable to heat, acid and alkali as carotenoids, and it will not be damaged by general cooking methods, but it is easily oxidized.
High temperature and ultraviolet rays can promote this oxidative damage, and it is more stable if it coexists with phospholipids, VE, VC and other antioxidants.
(1) Physiological function
1. Participate in the synthesis and regeneration of retinal rhodopsin, maintain normal dark adaptation and maintain normal vision.
2. Participate in the biosynthesis of glycoprotein in epithelial cells and mucosal cells, and maintain the normal structure and function of epithelial cells.
3. Promote the biosynthesis and differentiation of bone cells in protein, and promote the growth of the body and the development of bones.
4. Immunoglobulin is also a glycoprotein, and its synthesis is related to VA, so it can increase the body's anti-infection effect.
5.VA can promote the normal differentiation of epithelial cells and control their malignant transformation, thus preventing cancer.
(B) VA deficiency
Due to the nutritional deficiency caused by insufficient intake of VA and VA, the dark adaptation ability first decreases in clinic, and further development can form night blindness.
Hyperplasia and hyperkeratosis of skin basal cells, especially the transformation of hair follicle into hair follicle papules (mostly occurring on the surface of extensor muscles of limbs, shoulders, neck, back and around hair follicles of buttocks);
Sweat glands and sebaceous glands atrophy, dry skin and dry hair; Corneal keratosis and lacrimal gland secretion decrease, forming dry eye, and further development may lead to corneal ulcer, perforation,
Blindness, conjunctival folds and Pitting spots may also occur; Skeletal development is hindered, and immune and reproductive functions are reduced.
According to the WHO report, due to VA deficiency, 500,000 preschool children worldwide suffer from active corneal ulcer and 6 million suffer from dry eye every year, which affects vision and leads to blindness.
Important reasons.
People in our country eat less animal food, and mainly take β-carotene from vegetables, so mild VA deficiency is still quite widespread, and prevention should be strengthened.
System work.
(3) Hyperva
The excretion efficiency of VA after entering the body is not high, and long-term excessive intake can accumulate in the body, causing excessive VA. Adults can take 15000μg retinol equivalent every day for a long time.
Poisoning symptoms are mostly caused by excessive intake of VA preparation or eating the liver of wintering dogs or wolves. The main symptoms are anorexia, excessive irritability, peripheral pain at the end of long bones, and physical activity.
Limited, sparse hair, hepatomegaly, muscle stiffness, itchy skin, headache, dizziness, etc. Stop eating in time, and the symptoms will disappear quickly.
Adults ingest 99,000 ~ 33,000 μ g retinol equivalent at a time, and children consume more than 99,000 μ g retinol equivalent at a time, which may lead to acute VA poisoning. Adults appear after 6 to 8 hours.
Sleepiness or excessive excitement, headache, vomiting, increased intracranial pressure,12 ~ 30 hours later, the skin became red, swollen and thick, followed by peeling (especially on hands and soles); Acute infant illness
The main feature of the toxin is the increase of intracranial pressure, with fullness of anterior chimney, nausea, vomiting, fundus edema, increased cerebrospinal fluid pressure and sharp increase of serum VA content.
(4) Food sources
Natural VA exists only in animals. Animal liver, cod liver oil, milk, eggs and fish eggs are the best sources of VA. Pro-VA (the precursor of VA) carotenoids are widely distributed.
Among plant foods, β -carotene is the most important one. Red, orange and dark green plant foods are rich in β-carotene, such as carrots, sweet potatoes with red hearts,
Spinach, amaranth, apricot, mango, etc. Theoretically,1mol β -carotene can be decomposed into 2molVA in vivo, but because the absorption and utilization rate of carotene is much lower than that of VA, experiments prove that,
As far as its physiological activity is concerned, 6 μ g β -carotene can be equivalent to 1μgVA. β -carotene is the main source of VA in Chinese people's diet.
(5) Supply quantity
Infants and children have different supply levels (200 ~ 750 μ g retinol equivalent) at different ages, ranging from 13 years old to adult old age.
Pregnant women 1000μg, wet women 1200μg retinol equivalent.
1μg carotene =0. 167μg retinol equivalent. In the past, the amount of VA was usually expressed in international units (IU). 1 IUVA=0.33μgVA=0.33μg retinol equivalent.
When both VA and β -carotene are ingested from the diet, they should all be converted into μg retinol equivalent, namely:
Retinol equivalent (μg)=VA(μg)+0. 167×β- carotene (μg).
(VI) Evaluation of human VA nutritional status
The commonly used indicators for evaluating the nutritional status of VA in human body are:
① Determination of serum VA content. The normal content of serum VA in adults is 300 ~ 900μ g retinol equivalent /L, and it is deficient when it is lower than 120μg, but the level of serum VA is influenced by many factors.
Therefore, we should make a concrete analysis of the specific situation;
② Determination of visual dark adaptation function. The dark adaptation ability of VA deficient people is worse than that of normal people.
③ Determination of retinol protein in plasma. It is reported abroad that there is a positive correlation between its content and plasma VA content.
Second, vitamin D(VD)
VD is a general term for all steroids with biological activity of cholecalciferol. Among them, VD2 (calciferol) and VD3 (cholecalciferol) are the heaviest.
Yes, VD. VD2 and VD3 are both fat-soluble vitamins, which are similar in structure and function, and are stable to heat, oxygen, acid and alkali, which is mainly different from the source of VD2.
In plants, most plants contain trace amounts of ergosterol, and leaves of plants are exposed to sunlight to form VD2 (ergocalciferol or calciferol) and VD3 (cholecalciferol or bile).
Calcium alcohol) comes from animals, and 7- dehydrocholesterol in human and animal skin can be transformed into VD3 after ultraviolet irradiation, and then transported to liver and kidney to be transformed into bioactive forms.
And then play its important physiological function.
(1) Physiological function
VD is very important for bone formation. Its main function is to regulate calcium and phosphorus metabolism, promote the absorption and utilization of calcium and phosphorus by small intestine, and form sound bones and teeth.
(2) VD deficiency
VD is closely related to calcium and phosphorus metabolism in the body. Therefore, when VD is deficient, rickets will occur in children and osteomalacia and osteoporosis will occur in adults. Rickets often occurs in infants,
Due to the enlargement of cartilage joint and bone position of bone, square skull, beaded ribs and chicken breast can be seen clinically; Due to osteomalacia, the part of the bone under great pressure bends.
Deformation, such as curvature of the spine and lower limbs, can also cause the fontanel to close slowly and form Harrison's sulcus between the chest and abdomen. If VD is lacking in adults, it can decalcify mature bones and lead to bone formation.
Osteomalacia and osteoporosis are most likely to occur in women during pregnancy and lactation. The most common sites are pelvis and lower limbs, and then gradually spread to the spine and other parts.
(3) HyperVD
VD can accumulate in the body, and too much intake can cause VD excess. Adults take 2500μg daily and children take 500 ~1250 μ g daily, and poisoning can occur after several weeks.
It is characterized by headache, anorexia, nausea, thirst, polyuria, low fever, lethargy, increased serum calcium and phosphorus, calcification of soft tissue, renal failure, hypertension and other symptoms.
Stop eating and return to normal after a few weeks.
(4) Food sources
The foods with the richest content of VD3 are cod liver oil, animal liver and egg yolk, while the content of VD3 in milk and other foods is less. VD2 comes from plant food. Generally speaking, people only need
Can often contact the sun, under the general dietary conditions, will not cause VD deficiency. Babies who take milk as their staple food should be properly supplemented with cod liver oil and often exposed to sunlight.
Conducive to growth and development
(5) Supply quantity
Adults provide 5μg daily, and pregnant women, nursing mothers, children, adolescents and the elderly are all10 μ g.
(VI) Nutritional status assessment
At present, high performance liquid chromatography (HPLC) is widely used to determine 25-OH-D3 in plasma as an index to identify the nutritional status of VD3, and the results are accurate and reliable.
Iii. vitamin E(VE)
VE is the general name of all chromone derivatives with α -tocopherol biological activity, among which α -tocopherol has the highest activity. Soluble in fatty solvents, stable to heat and acid, and alkali.
Sensitive, can be slowly destroyed by oxidation.
(1) Physiological function
VE has a strong antioxidant effect, which can prevent unsaturated fatty acids from being damaged by peroxidation, thus maintaining the integrity and integrity of cell membranes with more unsaturated fatty acids.
Constant function; Because lipid peroxidation is prevented, the damage of other components in the body by lipid peroxide is eliminated. Therefore, it has the functions of delaying aging and preventing large cell lysis.
Blood anemia; It is also related to the development of sexual organs and embryos. Animal experiments show that the lack of VE in rats will cause damage to the reproductive system of females and males and make the reproductive epithelium hair.
Irreversible changes, male can cause sperm to stop forming and testicular degeneration, and female can cause embryo death. Clinically, it is often used to treat infertility and habitual abortion.
(2) Food sources
All kinds of vegetable oils (wheat germ oil, cottonseed oil, corn oil, peanut oil, sesame oil), germ of grain, many green plants, meat, cream, milk, eggs, etc. are all VE good or.
A better source.
(3) Supply quantity
3 ~ 8 mg for children, 10mg for adolescents and adults, and 12mg for pregnant women, nursing mothers and the elderly.
(4) Evaluation of nutritional level
1. Determine the content of α -tocopherol in serum, which is an index that directly reflects the adequacy of VE storage in the body. It is generally considered that less than 5mg/L is a poor nutritional status.
2. In vitro test of red blood cells, those who lack VE in vivo are more sensitive to hemolysis caused by H2O2 than normal people.
Iv. vitamin B 1(VB 1)
VB 1 (thiamine) is very easy to be damaged at high temperature, especially in high-temperature alkaline solution, and is easily damaged by ultraviolet rays, and it is stable in acidic solution.
Good, even when heated, it is stable.
(1) Physiological function
VB 1 is the main component of decarboxylation coenzyme, which is involved in the oxidative decarboxylation of pyruvate and α -ketoglutarate in carbohydrate metabolism. It can inhibit the activity of cholinesterase and maintain gastrointestinal tract.
Normal peristalsis of Tao and secretion of digestive gland.
(B) VB 1 deficiency
When VB 1 is absent, carbohydrate metabolism in nerve tissue is firstly hindered, which causes pyruvate to accumulate in nerve tissue, causing polyneuritis and beriberi.
Also known as beriberi, it is more common in areas where rice is the staple food. It is especially common in Southeast Asia, especially in the Philippines, Vietnam, Thailand, Myanmar and other countries. China has been rare since the founding of the People's Republic of China.
However, in recent years, due to the improvement of living standards, the consumption of refined white rice has increased, and the prevalence rate has rebounded in some areas. It can also be absorbed too little due to alcoholism and various gastrointestinal diseases.
Consumptive diseases such as tuberculosis and hyperthyroidism make it relatively insufficient and cause the disease.
Due to insufficient diet, symptoms usually appear after taking a low VB 1 diet for 3 months. Early manifestations are fatigue, muscle aches, loss of appetite and weight loss.
Then there are typical symptoms: ascending symmetrical peripheral neuritis, which first occurs in the lower limbs and is distributed like socks; Abnormal sensation, muscle weakness, tachycardia, precordial area
Pain; Severe cases are manifested as heart failure and edema. Clinically, it can be divided into four types:
① Dry type, with peripheral neuritis as the main manifestation;
② Wet type, mainly edema and serous exudation;
(3) fulminant type, characterized by acute cardiovascular system, accompanied by phrenic nerve and recurrent laryngeal nerve paralysis;
(4) mixed type, with the above two or more manifestations.
(3) Food sources
Foods rich in VB 1 include cereals, beans, dried fruits, yeast and hard-shelled fruits, especially in the epidermis of cereals, so the grinding accuracy should not be excessive.
The contents of animal viscera, eggs and green leafy vegetables are also high, and the contents of celery leaves and lettuce leaves are also rich, which should be fully utilized. Although the content of potatoes is not high, potatoes are used
The region that is the staple food is also the main source of VB 1 Thiaminase is contained in some fishes and mollusks. Eating it raw can cause the loss of VB 1 in other foods, so
The saying "eat fish raw and shrimp alive" is neither hygienic nor scientific.
(4) Supply quantity
The demand of VB 1 is directly proportional to the total heat intake of the body, so the supply of VB 1 is expressed by the heat supply per 4.2MJ( 1000kcal). Accordingly, it is recommended in China.
VB 1 supply is 0.5mg/4.2MJ.
(5) Evaluation of nutritional level
1.The subjects took VB 15mg orally in the morning, and then collected urine within 4 hours. The VB 1 content was determined: <100μ g was nutritional deficiency, and100 ~ 200μ g was.
Insufficient, > 200μ g is normal, > 400μ g is abundant.
2. The ratio of VB 1 to creatinine content in urine on an empty stomach is less than 27, 27 ~ 65 is low, 66 ~129 is appropriate, and ≥ 130 is too high.
3. Determination of glycolaldehyde activity in red blood cells This is a specific indicator for determining the nutritional status of VB 1. If TPP (thiamine pyrophosphate) effect is greater than16%, it means that VB 1 is deficient.
V. Vitamin B2(VB2)
VB2 (riboflavin) is an orange-yellow crystal, which melts and decomposes at 280℃. It is stable to heat in neutral and acid solutions and easy to decompose and destroy in alkaline conditions. dissociate
VB2 is sensitive to light, especially ultraviolet light.
(1) Physiological function
VB2 is a coenzyme part of various flavases in the body, which plays a widely role in hydrogen transfer in the process of biological oxidation. Participate in the metabolic process of three thermogenic nutrients in the body, and heat energy.
Metabolism is directly related.
(B) VB2 deficiency (riboflavin deficiency)
Without VB2, there will be disorder of energy and substance metabolism, which is manifested in the syndrome of external genitalia, tongue, lips and mouth. According to two nutrition surveys in China, the average resident
The intake is only 1/2 of the standard supply. At present, people in China eat less animal food, which is easy to cause VB2 deficiency. Clinical manifestations are:
① angular stomatitis; ② cheilitis; ③ glossitis; ④ blepharitis; ⑤ Cystitis; ⑥ Seborrheic dermatitis.
(3) Food sources
Animal foods contain more VB2, especially in liver, heart and kidney, and milk and eggs are also abundant. Plant foods are generally low in content except green vegetables and beans.
(4) Supply quantity
Same as VB 1, 0.5mg/4.2MJ.
(5) Evaluation of nutritional level
1.Determine the content of VB2 in cells. This is a good index to evaluate the nutritional level of VB2. The content of <140μ g/L is deficient, and that of > 200μ g/L is good.
2. After oral administration of 5mgVB2 in load test, it is insufficient that the amount of VB2 excreted in urine is less than 350μ g within 4 hours.
3. VB2 creatinine ratio (μ g/g) < 27 is insufficient, 27 ~ 79 is low, 80 ~ 269 is suitable, and > 270 is abundant.
4. Determination of glutathione reductase activity The coefficient of enzyme reduction activity (AC) >1.2 indicates that VB2 in tissues is insufficient.
Vi. Nicotinic acid (VPP)
Nicotinic acid, also known as nicotinic acid, is the main existing form in biological tissues, and it is a biologically active derivative of nicotinic acid (VPP).
It can be hydrolyzed into VPP, both of which are relatively stable white crystals dissolved in water. Generally, VPP is called anti-furuncle vitamin. VPP is very stable at ordinary cooking temperature, and it is very stable in acid.
There won't be much loss in sexual or alkaline solution.
(1) Physiological function
VPP is an important component of coenzyme I and coenzyme II, both of which are coenzyme of dehydrogenase, which plays the role of transferring hydrogen atoms in the process of biological oxidation. Without VPP, people
The body cannot use carbohydrates, fats and protein to generate energy, nor can it synthesize protein and fat; It plays an important role in maintaining the normal functions of skin, nerve and digestive system.
Function; It also has the effect of dilating blood vessels.
(B) VPP deficiency (also known as leprosy, pellagra)
VPP deficiency (pellagra) mostly occurs in areas where corn is the staple food. In the past, residents in southern Xinjiang used corn as the staple food for quite some time, and they did not have the habit of adding alkali to eat it.
The supply of non-staple food is insufficient, so there has been an epidemic of leprosy, and the prevalence rate of residents in some areas is as high as 50%. After long-term prevention and treatment, coupled with the improvement of living standards, the disease has been basically obtained at present.
Control.
Its typical symptoms are dermatitis, diarrhea and demantia, so-called "three-D" syndrome. Early often have loss of appetite, indigestion, abdomen.
Diarrhea, insomnia, headache, weakness, weight loss and other phenomena. Followed by symmetrical dermatitis in the exposed part of the skin, redness, itching, dark brown skin, pigmentation and rough skin,
There is obvious edema, which may be accompanied by herpes, ulcer and infection. There is also inflammation in the digestive tract and tongue, with scarlet tongue, ulcer, nausea, vomiting, diarrhea and other symptoms. nervous system
In addition to the early symptoms, there are muscle tremor, tendon reflex allergy or disappearance, irritability, anxiety, depression, forgetfulness, and a few patients may have mental disorders. Other symptoms are female vagina.
Inflammation, irregular menstruation, burning sensation when men urinate, loss of libido, etc.
(3) Food sources
The foods rich in VPP are animal liver, yeast, peanuts, whole grains, beans and meat. The content of VPP in corn is not small, but it is combined and cannot be directly absorbed by human body.
Absorb and utilize. Therefore, in order to prevent furuncle, corn is treated with alkali (for example, corn is treated with lime in Mexico, and corn with alkali is popularized in Xinjiang, China).
A large amount of free VPP can be released, which has achieved good results in the prevention of furuncle. At the same time, the proportion of beans, rice and wheat flour should be increased in the diet to reduce the intake of corn.
Input.
In addition, part of the VPP needed in the body can be converted from tryptophan, and about 60mg of tryptophan can be converted into 1mgVPP.
(4) Supply quantity
It is not only directly proportional to the heat energy demand, but also 10 times the supply of VB/kloc-0 and VB2, and the recommended supply is 5 mg/4.2 mj.
(5) Evaluation of nutritional level
1.Determination of the excretion of VPP metabolites The forms excreted from urine are mainly N'- methylnicotinamide (N'-Me) and 2- pyridone-methylnicotinamide (2- pyridone).
When the total amount of the two drugs is more than 5 mg, it is normal. If the N'-Me is 0.5 ~ 0.8 mg, 2-pyridone <1mg is deficient, and clinical symptoms will appear soon. 2- pyridone /N' used abroad
–me ratio to evaluate the nutritional level of VPP, with the ratio >1.3 as normal and <1as deficiency.
2. the subjects were given a standard diet, which provided VPP 10mg and tryptophan 1000mg. urine was collected for 24 hours, and the contents of N'-Me and 2- pyridone in urine were determined, which showed a relatively low nutritional level.
The total amount of the two metabolites is 7.0 ~ 37 mg in good patients, and less than 3 mg in patients with leprosy.
Vii. vitamin c (ascorbic acid, VC)
VC(ascorbic acid) is an acidic polyhydroxy compound, which is easily soluble in water and relatively stable under dry and light-free conditions. Easily oxidized, heated or exposed to air,
Alkaline solution and metal ions (Cu2+,Fe3+) can accelerate its oxidation.
(1) Physiological function
Participate in the redox process in vivo, maintain the normal energy metabolism of tissues and cells and adjust the intracellular redox potential; Promote collagen synthesis in vivo; Trivalent iron in plasma transferrin
Reducing to ferrous iron to promote the absorption of iron; Increase the body's disease resistance and promote wound healing; Blocking the formation of nitrosamines in the body, with anti-cancer and anti-cancer effects; A lot of VC is ok
Promote myocardial utilization of glucose and synthesis of myocardial glycogen.
(B) VC deficiency
Lack of VC in human beings can cause scurvy, which is characterized by increased capillary fragility, swelling and bleeding of gums, loosening and shedding of teeth, petechiae and ecchymosis on skin, and joint bleeding.
Hematoma, epistaxis, bloody stool, menorrhagia. It can also affect the normal calcification of bones, resulting in poor wound healing, low resistance and tumor spread. Fresh fruits in northern China
There are fewer vegetables than in the south, so VC deficiency is more common than in the south.
(3) Food sources
VC mainly comes from fresh vegetables and fruits, among which Ziziphus jujuba, hawthorn, citrus, strawberry, wild rose fruit, Mimickey peach and so on are high in content; Pepper has the most content in vegetables, while other vegetables.
Vegetables also contain more VC, the content of leaves in vegetables is higher than that in stems, the new leaves are higher than the old leaves, and the photosynthetic leaves have the highest content. Dried beans and seeds do not contain VC, but when beans or seeds
After the seeds germinate, VC can be produced.
(4) Supply quantity
From birth to 12 years old, it is 30 ~ 50mg according to different ages, 60mg for teenagers, adults and the elderly, 80mg for pregnant women and 0/00 mg for wet nurses.
(5) Evaluation of nutritional level
1.after oral administration of 500mgVC, the urine output of 4 hours is normal,1~ 3 mg is insufficient, and <1mg is deficient.
2. Determining the content of VC in white blood cells < 2 mg/100g is malnutrition.