Vitamins are organic compounds that are essential to human metabolism. The human body is an extremely complex chemical plant, constantly carrying out various biochemical reactions. The reactions are closely related to

enzyme catalysis. To produce enzyme activity, there must be coenzymes to participate. It is known that many vitamins are coenzymes of enzymes or are constituent molecules of coenzymes.

Therefore, vitamins are important in maintaining and regulating the normal metabolism of the body. Vitamins can be considered to be present in human tissues in the form of "biologically active substances".

Most of the vitamins cannot be synthesized in the human body, or the amount of synthesis is insufficient to meet the needs of the human body. Therefore, they must be taken from food. The content of vitamins in food

is relatively small, and the human body does not need much, but it is a substance that can never be reduced. Dietary vitamin deficiency will cause metabolic disorders in the human body, resulting in vitamin deficiency.

such as lack of vitamin A will appear night blindness, dry eyes and dry skin;

lack of vitamin D can suffer from rickets;

lack of vitamin B1 can get foot fungus;

lack of vitamin B2 can be affected by lipitis, stomatitis, lingual inflammation and scrotal inflammation;

lack of PP can be affected by mangina;

lack of vitamin B12 can suffer from pernicious anemia;

lack of vitamin B12 can be affected by anemia;

lack of vitamin B12 can be affected by pernicious anemia. B12 can suffer from pernicious anemia;

Vitamin C deficiency can suffer from scurvy.

Vitamins are a huge family, on the current knowledge of vitamins there are dozens of kinds of vitamins, can be roughly divided into (fat-soluble) and (water-soluble) two categories.

The former includes vitamins A, D, E, K, and the latter includes B vitamins and vitamin C, as well as many "vitamin-like".

The main vitamins found in medicine now are:

Fat-soluble vitamins

Vitamin A: Maintains normal vision and prevents night blindness; maintains healthy epithelial cell tissues; promotes growth; increases resistance to infectious diseases;

Prevents and treats dry eye disease.

Vitamin D: regulates the metabolism of calcium and phosphorus in the body, promotes absorption and utilization, and promotes bone growth.

Vitamin E: Maintain normal fertility and muscle metabolism; maintain the integrity of the central nervous and vascular systems.

Vitamin K: Hemostasis. It is not only the main component of plasminogen, but also induces the liver to make plasminogen. Pediatric Vitamin K Deficiency

Water-soluble Vitamins

Vitamin B1: Maintains normal circulatory, digestive, neurological, and intramuscular functions; regulates gastrointestinal functions; constitutes a coenzyme of decarboxylase, and participates in the metabolism of sugar; and prevents beriberi.

Vitamin B2: also known as riboflavin. Riboflavin is a component of many important coenzymes in the body, these enzymes can transfer hydrogen in the body's metabolic process, it is also protein,

sugar, fatty acid metabolism and energy utilization and composition of the necessary substances. It can promote growth and development, and protect the health of eyes and skin.

Pantothenic acid (vitamin B5): anti-stress, anti-cold, anti-infection, prevent the toxicity of some antibiotics, eliminate postoperative bloating.

Vitamin B6: plays an important role in protein metabolism. Treatment of neurasthenia, vertigo, atherosclerosis.

Vitamin B12: anti-fatty liver, promote the storage of vitamin A in the liver; promote cell maturation and body metabolism; treatment of pernicious anemia.

Vitamin B13 (lactic acid clear).

Vitamin B15 (Pantethine). Mainly used for anti-fatty liver, increase the rate of oxygen metabolism in the tissues. Sometimes used to treat coronary heart disease and chronic alcoholism.

Vitamin B17. highly toxic. Some people believe it has cancer-controlling and preventive effects. Para-aminobenzoic acid. One of the most recently discovered vitamins in the B vitamin family.

Synthesized in the body.

Inositol: One of the B vitamins, and like choline, a lipophilic vitamin.

Vitamin C: Connects bones, teeth, and connective tissue structures; has a bonding function between individual cells of the capillary wall; increases antibodies and strengthens resistance; promotes maturation of red blood cells.

Vitamin P: Vitamin PP (niacin). In the cell physiological oxidation process plays a role in the transmission of hydrogen, has the effect of preventing and controlling mange.

Folic acid (vitamin M): anti-anemia; maintenance of normal cell growth and immune system function.

Vitamin T: helps blood clotting and platelet formation.

Vitamin U: important in the treatment of ulcers.

Vitamins are organic compounds needed for nutrition and growth. If the organism is deficient in vitamins, a certain disease will occur. Therefore, some people think that vitamins are nutrients, and that it is better to take them in

The more vitamins you take, the better. The more vitamins a person needs, the better? The answer is no. The key to proper nutrition is "moderation". Excessive intake of certain vitamins is not

only unhelpful but harmful to the body.

We know that vitamins can be broadly divided into water-soluble (vitamins B, C) and fat-soluble (vitamins A, D, K, etc.) two categories. Water-soluble vitamins can be excreted in urine

Fat-soluble vitamins A or D, the excess can not be excreted. This gives people the impression that water-soluble vitamins eat more harmless, some people advocate

daily oral vitamin C 3-5 grams to achieve the purpose of health care. In fact, this is harmful, experiments have confirmed that long-term daily dose of vitamin C1 grams or more, can cause oxaluria, hyperuricemia

hemoglobinaemia, hyperglobinaemia. Some people may have a rash, swelling, blood pressure drop, nausea. In fat-soluble vitamins, vitamin A and vitamin D overdose caused by

the most common poisoning. Vitamin A excess, will cause insomnia, asthma, dizziness, hair loss, nausea, diarrhea, etc.; vitamin D excess, can cause loss of appetite, tiredness,

constipation, weight loss and low fever.

Normal people need daily vitamin C50-100 mg, vitamin A2500-3000 international units, vitamin D300-400 international units.

Nutritionally speaking, the so-called vitamins should be the human body can not be synthesized (or synthesized in quantities that do not meet the needs) but in the body's normal metabolic processes and regulate physiological function of the indispensable

a class of substances. They are nutrients that must be supplied by food. Therefore, in case of deficiency, some typical clinical symptoms will appear. Up to now, no deficiency has been found due to a lack of bitter almond

glycosides, so these two substances can not be called vitamins at all.

Vitamin B15 and vitamin B17 are some nutritional scholars in foreign countries proposed beneficial to human health of food ingredients, and named as vitamins, but so far have not been recognized by the world scholars

.

In recent studies, vitamins also have some special functions, such as pantothenic acid mood regulation, folic acid and vitamin B12 to reduce the role of DNA loss, folic acid and B6

Beneficial cardiovascular and so on.

For vitamin supplementation, you should supplement with both diet and vitamin preparations. Fruits and vegetables are high in vitamins, but since the vitamin content of each vegetable and fruit is

different, it may not be possible to supplement vitamins in a balanced manner in all aspects, and fruits and vegetables lose vitamins in processing and cooking, so vitamin preparations can play a balanced role.

But vitamin preparations are not easily absorbed and are not naturally green, so it is better to supplement with fruits and vegetables.

Precautions when taking vitamins||Misconceptions about Vitamins||Common Vitamin Preparations||Vitamin Supplemental Therapy||Vitamins and Children's Health Related: Vitamins

And Health Columns (Columnist: Lin Fanshun)Carotene

References:

How Vitamins Work

If we envision the human body as the If we think of the human body as the engine of an automobile, vitamins are like pistons. What does this amazing substance, which is found in very small amounts in food, do for the human body?

● Vitamins normalize the body's metabolism through the enzyme system. A deficiency of just one vitamin can jeopardize the entire body.

Vitamins are the building blocks of the body's enzyme system. This enzyme system is like the ignition of a piston - regulating the body's condition, making all parts work efficiently, promoting normal metabolism, and normalizing the whole body.

Compared to other nutrients such as protein, fat, and carbohydrates, the amount of vitamins consumed (even in large quantities for therapeutic purposes) is very small

. However, a deficiency in any one of these vitamins can lead to a dangerous situation for the entire body.

The main causes of vitamin deficiency are:

1) Inadequate dietary levels. Can be due to poverty, dietary monotony, partiality, etc. so that the amount of dietary vitamins can not meet the body's needs;

② body absorption disorder. Such as intestinal peristalsis accelerated, absorption area is reduced, long-term diarrhea, etc. so that the absorption of vitamins, storage is reduced;

③ increased discharge. Can be due to lactation, sweating, long-term use of diuretics and other large amounts of increased discharge;

4 accelerated destruction of vitamins in the body due to the role of drugs;

5 physiological and pathological need to increase;

6 irrational food processing and cooking vitamins destroyed or lost in large quantities.

Prevention of vitamin deficiency measures:

①Provide a balanced diet;

②Adjust the supply of vitamins in accordance with the body's physiological and pathological conditions;

3 Timely treatment of intestinal diseases affecting the absorption of vitamins;

④Reasonable processing of food cooking to minimize the loss of vitamins.

Fat-soluble vitamins, including A, D, E, K four, in the food and lipid **** with the existence of intestinal absorption and lipid absorption, excretion efficiency is low, so the intake of excessive,

can be accumulated in the body, resulting in harmful effects, and even poisoning. Water-soluble vitamins include B vitamins (B1, B2, B6, B12, PP, etc.) ascorbic acid (VC).

Water-soluble vitamins features:

1) soluble in water, insoluble in fat and organic solvents;

2) easy to discharge from the urine, and discharge efficiency, so a large number of ingested generally do not produce accumulation and toxic effects;

3) the vast majority of the form of coenzymes or cofactors to participate in the work of the enzyme system in the intermediary metabolism of the many links play an important role;

3) the vast majority of co-enzyme or cofactor form, in the intermediary metabolism of many aspects of the work of the enzyme system.

3 Most of them participate in various enzyme systems in the form of coenzymes or cofactors, and play an important role in many aspects of intermediary metabolism.

I, vitamin A (VA) and vitamin A original (carotenoids)

Vitamin A (retinol), also known as retinol, and carotenoids, like heat, acid, alkali stability, general processing and anti-cooking methods will not cause damage, but easy to oxidize,

High temperatures and ultraviolet rays can promote the oxidation of damage, and if the coexistence with phospholipids, VE and VC and other antioxidants is more If coexist with phospholipids, VE and VC and other antioxidants is more stable.

(I) Physiological functions

1. Participate in the synthesis and regeneration of retinal retinal uvea, maintain normal dark adaptation ability, maintain normal vision.

2. It participates in the biosynthesis of glycoproteins in epithelial cells and mucosal cells to maintain the normal structure and function of epithelial cells.

3. It promotes protein biosynthesis and differentiation of osteoblasts, and facilitates growth and bone development.

4. Immunoglobulin is also a glycoprotein, and its synthesis is related to VA, so it has the effect of increasing the body's resistance to infection.

5. VA can promote the normal differentiation of epithelial cells and control their malignant changes, thus having an anti-cancer effect.

(2) VA deficiency disease

The nutritional deficiency disease caused by insufficient intake of VA and VA original, clinically, the first appearance of the dark adaptation ability to reduce the further development of night blindness can be formed.

Skin basal cell hyperplasia and hyperkeratosis, especially follicular keratinization as follicular papules (mostly occurring on the surface of extensor muscles of the limbs, shoulders, neck, back, buttocks around the hair follicles);

Sweat glands, sebaceous glands atrophy, skin dryness, hair dryness and shedding; conjunctival keratinization, reduced secretion of the lacrimal glands, the formation of dry eye, and further development of the cornea can be ulceration, perforation,

Blindness, and also the formation of night blindness.

Blindness, conjunctival folds and Biden's spots can also occur; skeletal development is hindered, immune and reproductive functions decline.

According to WHO, 500,000 preschool children worldwide suffer from active corneal ulcers and 6 million people suffer from dry eye every year due to VA deficiency, which is an important cause of vision and blindness.

China's people dietary intake of animal food is small, mainly from vegetables in the intake of beta-carotene (β-carotene) so mild VA deficiency is still quite widespread, should strengthen the prevention

System work.

(C) VA overdose

VA is not efficiently excreted into the body, and long-term excessive intake can accumulate in the body, causing VA overdose. Adults who consume 15000μg of retinol equivalent per day for a long time can develop

Toxicity, mostly due to excessive intake of VA preparations or ingestion of the liver of dogs or wolves over winter. The main symptoms are anorexia, hyperarousal, peripheral pain at the end of the long bones, limb movement

restriction, hair thinning, liver enlargement, muscle stiffness, itchy skin, headache, dizziness. If you stop consuming it in time, the symptoms will disappear soon.

Adults ingesting VA 99000~33000μg retinol equivalent, children exceeding 99000μg retinol equivalent, can be acutely poisoned by VA. Adults in 6 to 8 hours after the emergence of

drowsiness or over-excitement, headache, vomiting, increased intracranial pressure, 12 to 30 hours after the skin redness and swelling and thickening, followed by peeling (to the palms of the hands and feet is most obvious); infants and young children acute poisoning

toxicity with increased intracranial pressure as its main feature, the emergence of the front of the chimney fullness, nausea, vomiting, fundus oedema, cerebrospinal fluid pressure increases, serum VA content increased dramatically. The cerebrospinal fluid pressure increases, and the serum VA level increases dramatically.

(D) Food sources

Natural VA exists only in animals. Animal liver, cod liver oil, milk, eggs and fish eggs are the best sources of VA. VA proto (precursor of VA) carotenoids are widely distributed

in plant foods, the most important of which is β-carotene. Red, orange, and dark green plant foods are rich in beta-carotene, such as carrots, sweet potatoes,

spinach, amaranth, apricots, and mangoes. Theoretically, 1mol of β-carotene can be decomposed into 2mol of VA in the body, but since the absorption and utilization rate of carotene is much lower than that of VA, experiments have proved that

in terms of its physiological activity, 6 μg of β-carotene can only be equivalent to 1 μg of VA. β-carotene is the main source of VA in the diets of the people in China.

(E) supply

Infants and children of different ages, the supply varies (200-750 μg retinol equivalent), from 13 years of age teenagers to the elderly adults are 800 μg retinol equivalent.

1000 μg for pregnant women and 1200 μg retinol equivalent for lactating mothers.

1μg carotene = 0.167μg retinol equivalent. In the past, the amount of VA was often expressed in international units (IU).1 IUVA = 0.33 μg VA = 0.33 μg retinol equivalent.

When both VA and β-carotene are consumed in the diet, all of them should be converted into μg of retinol equivalents, i.e.

Retinol equivalents (μg) = VA (μg) + 0.167 × β-carotene (μg).

(F) human VA nutritional status assessment

Assessment of the human body VA nutritional status of commonly used indicators:

① Determination of serum VA content. Adult serum VA normal content of 300 to 900 μg retinol equivalent / L, less than 120 μg for the lack of, but because the serum VA content is affected by many factors,

So should be a specific analysis of specific cases;

② visual dark adaptive function measurement. VA deficient dark adaptive ability is worse than the normal people;

③ plasma retinol protein measurement. It is reported that there is a positive correlation between its content and plasma VA content.

Two, vitamin D (VD)

VD is a collective term for all steroids with cholecalciferol biological activity. Among them, VD2 (calciferol) and VD3 (cholecalciferol) are the most important

VD. VD2 and VD3 are similar in structure and function, and are fat-soluble vitamins, which are stable to heat, oxygen, acid and alkali, but the main difference is that the two are from different sources, and the source of VD2 is from plants. Most plants contain trace amounts of ergosterol, plant leaves exposed to sunlight to form VD2 (called ergocalciferol or calcitriol), VD3 (also known as cholecalciferol or cholecalciferol

calciferol) from animals, human and animal skin 7-dehydrocholesterol can be converted to VD3 after ultraviolet light irradiation, and then transported to the liver and kidneys to be converted into a biologically active form,

and then The VD3 is then transported to the liver and kidney to be converted into a biologically active form,

which then performs important physiological functions.

(I) Physiological function

VD is extremely important for bone formation, and its main function is to regulate calcium and phosphorus metabolism, promote the absorption and utilization of calcium and phosphorus in the small intestine, and constitute sound bones and teeth.

(2) VD deficiency

VD is closely related to calcium and phosphorus metabolism in the body, so when VD deficiency, rickets occurs in children and osteomalacia and osteoporosis in adults. Rickets often occurs in infants and young children,

Because of the cartilage joints of the skeleton and the skeletal parts of the skeleton increase in size, clinically can be seen in the square skull, rib beads, chicken breast; due to the softening of the bone, the bone part of the skeleton to withstand the greater pressure to bend

Deformation, such as spinal curvature, curvature of the lower limbs, but also can occur fontanelle closure retardation, the formation of the chest and abdomen, between the Harrison's ditch. If the adult lacks VD, can make the mature bone decalcification, and the occurrence of bone

chondromalacia and osteoporosis, pregnant and lactating women are most likely to occur, the most common parts of the pelvis and lower limbs, and then gradually spread to the spine and other parts of the body.

(C) VD overdose

VD can be accumulated in the body, and excessive intake can cause VD overdose. Adults ingest 2500μg per day, children ingest 500～1250μg per day, poisoning can occur after a few weeks.

The symptoms include headache, anorexia, nausea, thirst, polyuria, hypothermia, drowsiness, increase in serum calcium and phosphorus, calcification of soft tissues, renal failure, hypertension and other symptoms.

Stop eating and return to normal after a few weeks.

(D) food sources

VD3 content of the richest food for the cod liver oil, animal liver and egg yolk, milk and other foods in the VD3 content is less. VD2 from plant foods, in general, as long as

can often contact with sunlight, in the general dietary conditions, will not cause VD deficiency. Milk-based diet of infants, should be appropriate supplementation of cod liver oil, and often receive sunlight exposure,

favorable to growth and development.

(E) supply

Adults daily supply 5μg, pregnant women, lactating mothers, children and adolescents and the elderly are 10μg.

(F) nutritional status assessment

Currently, high-performance liquid chromatography (HPLC) method is often used to determine the plasma 25-OH-D3, as an indicator of the identification of the nutritional status of the VD3, and the results are accurate and reliable.

Three, vitamin E (VE)

VE is all the α-tocopherol biological activity of the chromone derivatives of the collective term, with α-tocopherol activity is the highest. It is soluble in fat solvents, stable to heat and acid, sensitive to alkali

and can be slowly destroyed by oxidation.

(I) Physiological function

VE has a strong antioxidant effect, can prevent unsaturated fatty acids from damage by peroxidation, thus maintaining the integrity of the cell membrane and the integrity and normal function of unsaturated fatty acids

; as a result of the prevention of lipid peroxidation, thus eliminating the other components of the body by the damage of lipid peroxides. Therefore, it has the effect of delaying aging and preventing macrocytic soluble

hemolytic anemia; it is also related to the development of sex organs and embryos. Animal experiments have shown that the lack of VE in rats will cause damages to the reproductive system of both female and male animals, resulting in irreversible changes in the reproductive epithelium, and in males, spermatozoa can be halted and testes degraded, and in females, the death of embryos can be caused. It is commonly used to treat infertility and habitual abortion.

(2) Food sources

Various vegetable oils (wheat germ oil, cottonseed oil, corn oil, peanut oil, sesame oil), germ of grains, many green plants, meat, cream, milk, eggs, etc. are good or

better sources of VE.

(C) supply

Children for 3 to 8mg, teenagers and adults for 10mg, pregnant women, lactating mothers and the elderly for 12mg.

(D) Nutritional level assessment

1. Determination of serum alpha tocopherol content, which is a direct reflection of the body's VE storage is an indicator of the adequacy of the body is generally considered to be less than 5mg / L for the It is generally recognized that less than 5mg/L is considered to be a poor nutritional status.

2. In vitro erythrocyte test, the lack of VE in the body, its in vitro erythrocyte hemolysis caused by H2O2 is more sensitive than normal people.

Four, vitamin B1 (VB1)

VB1 (thiamine, thiamine) in high temperature, especially in high-temperature alkaline solution, is very easy to destroy, and susceptible to ultraviolet damage, in acidic solution, the stability of

better, and even when heated is also stable.

(I) Physiological functions

VB1 is the main component of decarboxylating coenzyme, which is involved in the oxidative decarboxylation of pyruvate and α-ketoglutarate in the metabolism of carbon-hydride; it can inhibit the activity of cholinesterase and maintain the normal peristalsis of gastrointestinal

tracts and the secretion of digestive glands.

(2) VB1 deficiency

VB1 deficiency, the nerve tissue of the carbon-hydride metabolism is first impeded, resulting in the accumulation of pyruvic acid in the nerve tissue, resulting in polyneuritis and beriberi,

also known as beriberi is most commonly found in areas where rice is the staple food. In Southeast Asia, especially in the Philippines, Vietnam, Thailand, Myanmar and other countries is particularly common. After the founding of China has been rare,

But in recent years, due to the improvement of living standards, consumption of refined white rice increased, in some areas of the prevalence of the disease has risen again. It can also be caused by alcoholism, various gastrointestinal diseases that make it too little absorption,

Tuberculosis, hyperthyroidism and other consumptive diseases that make it relatively insufficient to cause the onset of the disease.

Dietary deficiencies generally cause symptoms to appear after 3 months on a low VB1 diet. Early symptoms include fatigue, muscle aches, loss of appetite, and weight loss.

Subsequently, the typical symptoms appear: ascending symmetrical peripheral neuritis, which occurs first in the lower limbs and is distributed in the form of a stocking stuffer; sensory abnormalities, muscle weakness, tachycardia, precordial

pain; and, in severe cases, heart failure and edema. Clinically, it can be divided into four types:

①dry type, with peripheral neuritis as the main manifestation;

②wet type, with edema and plasma exudation as the main manifestation;

3rd, with acute cardiovascular manifestation as the main manifestation, accompanied by phrenic nerve and laryngeal recurrent nerve paralysis;

4th, with mixed type, with the manifestation of more than the two above mentioned types at the same time.

(C) Food sources

VB1-rich foods include grains and cereals, legumes, dried fruits, yeast, and hard-shelled fruits, especially in the epidermal part of grains and cereals, and should not be overly milled.

Animal offal, eggs and leafy greens are also high in content, celery leaves, lettuce leaves are also rich in content, should be fully utilized. Although the content of potatoes is not high, but with potatoes

the main food areas, is also the main source of VB1. Some fish and mollusks, containing thiaminase, eaten raw can cause the loss of VB1 in other foods, so

"Eat raw fish, live shrimp," said both unhygienic and unscientific.

(D) supply

VB1 needs and total body heat intake is proportional to the supply of VB1, so the supply of VB1 per 4.2MJ (1000kcal) caloric supply to how much, according to China's recommended

VB1 supply of 0.5mg/4.2MJ.

(E) nutritional level evaluation

1. p>1. Load test: The subjects were given 15mg of VB1 orally in the early morning, then urine was collected within 4 hours and the VB1 content was measured: <100μg is considered as nutritional deficiency, 100-200μg is considered as

insufficient, >200μg is considered as normal, >400μg is considered as sufficient.

2. Measurement of VB1 and creatinine content in fasting urine: the ratio of VB1 and creatinine is <27 as insufficient, 27-65 as low, 66-129 as appropriate, and ≥130 as too high.

3. Erythrocyte transhydroxyglyoxalase activity measurement This is a specific indicator of the nutritional status of VB1, if the TPP (thiamin pyrophosphate) effect > 16% that is, VB1 deficiency.

Fifth, vitamin B2 (VB2)

VB2 (riboflavin, riboflavin) for the orange-yellow crystals, 280 ° C melting and decomposition, in neutral and acidic solution is heat-stable, easy to decompose and destroy in alkaline conditions. Free

VB2 is sensitive to light, especially ultraviolet light.

(I) Physiological function

VB2 is the coenzyme part of various flavoprotein enzymes in the body, and widely plays the role of hydrogen delivery in the process of biological oxidation; it participates in the metabolic process of the three major thermogenic nutrients in the body, and is directly related to the metabolism of heat energy

.

(2) VB2 deficiency (riboflavin deficiency)

The lack of VB2 in the organism will lead to disorders in the metabolism of energy and substances, which will be manifested in the syndromes of the external genitalia, the tongue, the lips and the corners of the mouth. According to two nutritional surveys in China, the average

intake of the population is only 1/2 of the supply standard.

Currently, our people consume less animal food, which is easy to cause VB2 deficiency. Clinical manifestations are:

①Keratitis; ②Lipitis; ③Tongueitis; ④Blepharitis; ⑤Scrotalgia; ⑥Seborrheic dermatitis.

(C) food sources

Animal food contains more VB2, especially in the liver, heart, kidney rich, milk, eggs in the food content is also a lot; plant food in addition to green vegetables and beans are generally not high.

(D) supply

Same as VB1, 0.5mg/4.2MJ.

(E) nutritional assessment

1. Determination of cellular VB2 content This is a good indicator of the nutritional level of VB2, the content of ＜140μg/L for the lack of ＜200μg/L for good.

2. Load test: After 5mg of VB2 was taken orally, the amount of VB2 excreted in the urine in 4 hours＜350μg is considered insufficient.

3. VB2 creatinine ratio (μg/g) <27 is insufficient, 27～79 is low, 80～269 is appropriate, >270 is sufficient.

4. Glutathione reductase activity measurement Enzyme reduction activity coefficient (AC) > 1.2 indicates that VB2 is insufficient in the tissue.

Six, nicotinic acid (VPP)

Nicotinic acid (nicotinic acid), also known as niacin, in biological tissues, nicotinamide is the main form of existence, it is nicotinic acid (VPP) with biological activity of the derivatives,

can be hydrolyzed to VPP, both of which are water-soluble, stable white crystals, generally known as the anti-vitamin for VPP. VPP is very stable at normal cooking temperatures and does not lose much in acidic

or alkaline solutions.

(I) Physiological function

VPP is an important component of coenzyme I and coenzyme II, both coenzymes of dehydrogenase, in the process of biological oxidation, play a role in the transfer of hydrogen atoms, if there is no VPP, the body can not utilize the carbons, fats and proteins to produce energy, and also can not synthesize proteins and fats; maintain the normal function of the skin, nervous system and digestive system plays an important role.

It plays an important

role in maintaining the normal function of the skin, nervous system, and digestive system; it also dilates blood vessels.

(B) VPP deficiency disease (also known as mange, pellagra)

VPP deficiency disease (pellagra) occurs in areas where corn is the staple food, in the past, a considerable period of time in southern Xinjiang, residents of the corn-based diet, and no alkali consumption habits,

Insufficient supply of non-food items, so the epidemic of mange has occurred, and the prevalence rate of some residents of the region up to 50%. The prevalence rate is as high as 50%. After a long period of prevention and treatment, coupled with the improvement of living standards, the disease has been

control.

The typical symptoms are dermatitis (dermatitis), diarrhea (diarrhea) and dementia (dementia), the so-called "three Ds". Early on, there is often a loss of appetite, indigestion, abdominal

diarrhea, insomnia, headache, weakness, weight loss and other phenomena. Then symmetrical dermatitis appears on the exposed parts of the skin, with redness, itching, dark brown skin, hyperpigmentation, rough skin,

significant swelling, which may be accompanied by herpes, ulcers and infections. There is also inflammation of the digestive tract and tongue, with scarlet tongue, ulcers, nausea, vomiting and diarrhea. Nervous system

In addition to the early symptoms, there are muscle tremors, hypersensitive or absent tendon reflexes, irritability, anxiety, depression, forgetfulness, and in a few patients, mental disorders. Other symptoms include vaginitis in women, irregular menstruation, burning sensation during urination in men, and loss of libido.

(C) food sources

VPP-rich food for animal liver, yeast, peanuts, whole grains, beans and meat content is high; corn in the VPP content is not small, but for the binding type, can not be directly absorbed and utilized by the body

. Therefore, in order to prevent mange, the application of alkali treatment of corn (such as Mexico with lime treatment of corn, China's Xinjiang in the prevention and treatment of mange in the process of promotion of corn with alkali consumption)

can release a large number of free VPP, in the prevention of mange has received good results. At the same time, the proportion of beans, rice and wheat flour in the diet should be increased, and the intake of corn should be reduced

.

In addition, part of the body's VPP can be converted from tryptophan, about 60mg of tryptophan can be converted to 1mg of VPP.

(D) supply

Not only is it proportional to the amount of calorie needs, but also 10 times the amount of VB1, VB2 supply, the recommended amount of supply of 5mg/4.2MJ.

(E) Nutritional Levels Evaluation

1. Determine the amount of VPP metabolites excreted from the urine mainly in the form of N'-methylnicotinamide (N'-Me) and 2-pyridone-methylnicotinamide (2-pyridone),

The total amount of both of them excreted>5mg is normal, if the N'-Me is 0.5mg, the recommended amount is 5mg/4.2MJ. '-Me is 0.5-0.8mg, 2-pyridone <1mg for deficiency, and soon appear clinical symptoms. Overseas, the nutritional level of VPP is assessed by the ratio of 2-pyridone/N'

-Me, and the ratio of >1.3 is considered normal, and <1 is considered deficient.

2. The subjects were given a standard diet, which provided 10mg of VPP and 1000mg of tryptophan, and the urine was collected for 24 hours to determine the content of N'-Me and 2-pyridone in the urine, and the total amount of the two metabolites of the subjects with better nutritional level was 7.0-37mg, and the total amount of the subjects with mange was less than 3mg.

Seven, vitamin C (ascorbic acid, VC)

VC (ascorbic acid) is an acidic polyhydroxy compounds, soluble in water, dry and no light conditions are more stable. It is easily oxidized, and its oxidation can be accelerated by heating or exposure to air,

alkaline solution and metal ions (Cu2+,Fe3+).

(I) Physiological functions

Participate in the redox process in vivo, maintain the normal energy metabolism of tissue cells and regulate intracellular redox potential; promote collagen synthesis in vivo; plasma ferritin in the trivalent iron

Reduce the divalent iron to promote iron absorption; increase the body's resistance to disease, promote wound healing; block the formation of nitrosamine in vivo, has a It can prevent and fight cancer; a large amount of VC can also

promote the synthesis of myocardial utilization of glucose and myocardial glycogen.

(2) VC deficiency disease

Human lack of VC can cause scurvy, manifested as increased fragility of capillaries, swollen and bleeding gums, loose teeth, loss of teeth, petechiae and ecchymosis of the skin, bleeding in the joints can be formed

Hematoma, epistaxis, blood in the stool, menorrhagia. It can also affect the normal calcification of bones, poor wound healing, low resistance, tumor proliferation and so on. China's northern region of fresh fruit

vegetables than the south is less, so VC deficiency disease is more common than the south.

(C) food sources

VC mainly from fresh vegetables and fruits, fruits to sour dates, hawthorn, citrus, strawberries, wild rosehips, fruit, such as the high content of lemongrass; vegetables to chili peppers with the highest content of other vegetables

Vegetables also contain a greater number of VC, vegetables, leaf than the stem of the content of the high, the new leaves are higher than the old leaves, the highest content of photosynthesis of the leaves. Dried beans and seeds do not contain VC, but when beans or

seeds are sprouted, VC can be produced.

(4) Supply

From birth to 12 years of age depending on the age of the 30-50mg, teenagers, adults and the elderly are 60mg, pregnant women 80mg, breastfeeding mothers 100mg.

(5) Nutritional level assessment

1. Load test: After 500mg of oral PVC, 4 hours of urinary excretion>3mg is normal, 1-3mg is insufficient, and <1mg is deficient.

2. Determination of VC content in leukocytes <2mg/100g for undernutrition.

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