Among them, carbohydrate, protein and fat are also called "three energy-supplying nutrients".
Carbohydrate:
physiological function
(1) Energy supply: glucose is produced per gram 16 kilojoules (4 kilocalories), and carbohydrates ingested by human body are digested into glucose or other monosaccharides to participate in body metabolism. There is no specific amount of carbohydrates in everyone's diet. Nutrition experts in China believe that the calories generated by carbohydrates should account for 60-65% of the total calories. Usually, the carbohydrate intake is mainly polysaccharide, which is high in staple foods such as rice and noodles. While ingesting carbohydrates, other nutrients such as protein, lipids, vitamins, minerals and dietary fiber can also be obtained. However, the intake of monosaccharides or disaccharides such as sucrose cannot supplement other nutrients except calories.
(2) Composition of cells and tissues: Each cell contains carbohydrates, the content of which is 2%- 10%, mainly in the form of glycolipids, glycoproteins and proteoglycans, which are distributed in meninges, organelle membranes, cytoplasm and intercellular substance.
(3) Save protein: The carbohydrate in food is insufficient, so the body has to use protein to meet the energy required for physical activities, which will affect the body's use of protein to synthesize new protein and tissue regeneration. Therefore, it is totally inappropriate to eat meat instead of staple food, because there are few carbohydrates in meat, so that body tissues will use protein to generate heat, which is not good for health. Therefore, the minimum carbohydrate intake of dieters or diabetics should not be lower than 150g staple food.
(4) Maintaining the normal function of brain cells: Glucose is an essential nutrient to maintain the normal function of the brain. When the blood sugar concentration drops, brain tissue can damage the function of brain cells due to lack of energy, leading to dysfunction, dizziness, palpitation, cold sweat and even coma.
(5) Others: Glycoproteins and proteoglycans in carbohydrates have lubricating effects. In addition, it can control the permeability of meninges. It is also the precursor of some synthetic biomacromolecules, such as purine, pyrimidine and cholesterol.
The main physiological functions of carbohydrates:
1, an important substance that constitutes the body;
2. provide heat energy;
3. Energy necessary to maintain brain function;
4. Regulating fat metabolism;
5. Provide dietary fiber.
Lack of carbohydrates:
It is easy to cause energy malnutrition in protein.
Protein:
1, which can constitute the body: it plays an important role in the growth and development of the body, tissue repair and aging tissue renewal, and is the main "raw material" that constitutes the body;
2. It can constitute important physiologically active substances: the enzymes, antibodies and hormones of human body are all composed of protein;
3, can maintain osmotic pressure: in the case of extreme lack of protein, resulting in the lack of intracellular protein, intracellular water will penetrate into the cells too much, causing nutritional edema;
4. It can provide energy.
Fat:
1, supplying human body with heat. Fat is oxidized in the human body, turning into carbon dioxide and water, releasing heat. Fat produces about 2.2 times as much calories as the equivalent protein or carbohydrate. This shows that fat is an important source of heat in the body.
2, constitute the role of body tissue and bioactive substances. Fat is one of the important components of human cells, especially brain nerve, liver, kidney and other important organs contain a lot of fat. Fat also constitutes body tissues and bioactive substances in the body, such as the main components of cell membranes, forming phospholipids, glycolipids and so on.
3, the role of regulating physiological function. Because fat is not a good heat conductor, subcutaneous adipose tissue is an isolation layer to protect the body and prevent body temperature from escaping. So fat has the function of keeping body temperature. Fat can also store "fuel" for the body as a backup. After eating fat, the inexhaustible part can exist in the body and be reused when the body needs calories. In addition, fat can also protect internal organs, moisturize skin and prevent earthquakes.
4, the role of dissolved nutrients. Some vitamins that are insoluble in water but only soluble in lipids can be absorbed and utilized by the human body only in the presence of fat.
Vitamins:
There are two kinds, water-soluble vitamins and fat-soluble vitamins.
Fat-soluble vitamins mainly exist in animal foods, such as pigs, beef and mutton, animal liver, edible oil, etc.
Water-soluble vitamins are mostly found in plant foods, such as vegetables and fruits.
Vitamins mainly include vitamins A, B, C, D, E, K, PP and vitamins.
Functions of various vitamins
Vitamin A(Vit A), also known as retinol, actually includes all kinds of substances with retinol biological activity, namely Vit A 1 and Vit A2 from animal foods, β -carotene and other carotenoids from plant foods. Vitamin A is mainly involved in the structure and function of internal membrane. Therefore, it is related to normal growth and development, reproduction, vision and anti-infection. There are two main kinds of vitamin A obtained by human body from food. First, provitamin A, that is, various carotenoids, exists in plant foods, such as green leafy vegetables, yellow vegetables and fruits. First, vitamin A in animal foods mostly exists in animal livers, milk and dairy products (non-defatted) and eggs in the form of esters.
Vitamin D(Vit D) is a kind of compounds with biological activity of cholecalciferol, which can be converted into vitamin D3 and vitamin D2 by ultraviolet activation from vitamin D precursor, 7- dehydrocholesterol and ergosterol. Vitamin D is transformed into the active forms of 25-(OH)D3 and 1, 25-(OH)2D3 in the liver and kidney in vivo, and transported to the intestine, bones and kidneys, and works together with parathyroid hormone * * * to maintain the blood calcium level.
Vitamin C(Vit C)Vit C is reducible, and can scavenge free radicals together with other antioxidants such as glutathione to prevent lipid peroxidation. It also participates in the hydroxylation of cholesterol to form cholic acid, thus reducing the blood cholesterol content. When vitamin C is insufficient, it will affect collagen synthesis, resulting in delayed wound healing, fragile microvascular wall and bleeding to varying degrees. Because of the lack of gulonolactone oxidase, the human body cannot convert glucose into vitamin C, so vitamin C must be obtained from diet. If vitamin C in the diet cannot meet the needs, it can lead to vitamin C deficiency or deficiency, and vitamin C deficiency can cause scurvy.
Harm of taking a large amount of vitamin C: a few grams 1 can cause diarrhea and abdominal distension; 2. False negative results of fecal occult blood; 3. Decreased iron absorption, thalassemia, sideroblastic anemia and hemochromatosis; ④ Some patients have hyperoxaluria; 5 dialysis patients are prone to hyperoxalemia; Patients with glucose -6- phosphate dehydrogenase deficiency are prone to hemolysis.
Thiamine, also known as vitamin B 1, anti-neuritis factor, anti-beriberi factor. Participate in the metabolism of sugar and branched-chain amino acids in the body. Vitamin B 1 can regulate neurophysiological activities, which is related to heart activity, maintaining appetite, normal gastrointestinal peristalsis and digestive juice secretion. Vitamin B 1 deficiency is often caused by insufficient intake, increased demand and obstacles in absorption and utilization. It can also lead to liver damage and alcoholism. Long-term renal dialysis, total parenteral nutrition and long-term chronic fever can all occur. Serious deficiency can cause beriberi, which can be divided into dry beriberi, wet beriberi and infant beriberi. No toxic reaction was found when a large amount of vitamin B 1 was ingested.
Riboflavin, also known as vitamin B2, is an indispensable auxiliary group of various oxidase systems in the body. FMN and FAD (vitamin B2 is a component of FMN and FAD) are yellow enzyme auxiliary groups. Its function is electron transfer, which plays a controlling role in the respiratory chain reaction of cell metabolism and directly participates in redox reaction. It can also activate vitamin B6 and participate in the process of converting tryptophan into nicotinic acid. In addition, it is also related to the absorption, storage and mobilization of iron in the body, and also catalyzes the N- oxidation of various imines.
vitamin deficiency
Vitamins are a large class of substances with different chemical structures and physiological functions, which must be supplied through diet every day. When the supply is insufficient, it is easy to be insufficient. Vitamin deficiency is a gradual process in the body. At first, the reserve decreases, then it involves biochemical metabolism abnormalities, physiological function changes, and then histopathological changes, resulting in clinical symptoms and signs. Although vitamin deficiency is rare in China, subclinical deficiency is more common in some areas and some people. Because subclinical deficiency is not easy to find, but it has adverse effects on health, it needs special attention.
Vitamin C deficiency: Long-term lack of vitamin C in the diet will hinder the synthesis of collagen in the body and lead to scurvy. The early symptoms are burnout, followed by gum pain and bleeding, subcutaneous bleeding and slow wound healing. In severe cases, the teeth are loose, the gums are atrophied, the teeth fall off, and some mucous membranes bleed, which may cause symptoms such as nosebleeds and bloody stools. Children may have subperiosteal bleeding.
Thiamine deficiency: due to long-term insufficient intake, increased demand or obstacles in absorption and utilization. The nature and degree of its symptoms are related to the degree of deficiency, acute and chronic. Generally divided into the following categories: dry beriberi: with the symptoms of polyneuritis as the main symptom, there is ascending peripheral neuritis, which is characterized by numbness of fingers and toes, muscle pain and tenderness, especially gastrocnemius.
Wet beriberi: edema and heart symptoms are the main symptoms. If not treated in time, it will often lead to heart failure.
Infantile beriberi: Infants who mostly occur in February-May have a sudden onset and are in a hurry. Early loss of appetite, vomiting, excitement, rapid heartbeat, shortness of breath and difficulty. Cyanosis, edema, enlargement of the heart, heart failure and tonic spasm occur in the late stage, and they often die within 1-2 days after symptoms appear.
Riboflavin deficiency: mainly manifested as inflammation of eyes, mouth and skin. Eyes: conjunctival congestion, pericorneal vascular hyperplasia, and sometimes edema at the junction of cornea and conjunctiva.
Oral cavity: the mouth is wet and white, with cracks, pain and ulcers; Lip swelling, cracks, ulcers and pigmentation; Tongue pain, swelling, erythema and atrophy of tongue nipple.
Skin: seborrheic dermatitis. Common in sebum-rich parts.
Anemia: Vitamin B2 deficiency often interferes with the absorption, storage and mobilization of iron in the body, leading to the decrease of iron content, and even iron deficiency anemia in severe cases.
Others: Vitamin B2 deficiency also affects growth and development; Insufficient pregnancy can lead to fetal skeletal malformation.
Nicotinic acid deficiency: Nicotinic acid deficiency is a boil. Early symptoms are fatigue, fatigue, decreased working ability, poor memory and frequent insomnia. Typical symptoms are dermatitis, diarrhea and dementia, the so-called "three D" symptoms.
Vitamin A deficiency: When dietary vitamin A or provitamin A is insufficient, or absorption, storage and utilization are affected, vitamin A deficiency can often be caused. The manifestations are: decreased dark adaptation, night blindness and dry eye; Mucosal epithelial changes; Growth and development are blocked; Others: taste and smell are weakened, and appetite is reduced.
Vitamin D deficiency: lack of vitamin D in diet or insufficient sunlight are the two main reasons for vitamin D deficiency. Vitamin D deficiency leads to decreased absorption of calcium and phosphorus, decreased blood calcium level, bone inorganic obstruction, osteomalacia, infantile rickets and adult osteomalacia.
Vitamin e deficiency: vitamin e deficiency rarely occurs in humans, which may be due to the following reasons: vitamin e is widely found in food; Vitamin E is stored in almost all organs and tissues of human body. Vitamin e can be stored in the body for a long time.
Dietary sources of vitamins
name
Main dietary sources
vitamin A
Green leafy vegetables, yellow vegetables, fruits, livers, milk and dairy products.
VD
Marine fish, liver, egg yolk, cream.
vitamin E
Oilseeds and vegetable oils
Vit B 1
Animal viscera, meat, beans, peanuts
Victor B2
Liver, kidney, heart, milk and eggs
Victor B6
Beans, meat, liver, fish
vitamin C
Fresh vegetables and fruits
folic acid
Liver, kidney, eggs, green leafy vegetables, yeast.
nicotinic acid
Liver, kidney, meat, fish, peanuts, grains.
Minerals:
1. Important components of body tissues: calcium, phosphorus and magnesium-bones and teeth. Lack of calcium, magnesium, phosphorus, manganese and copper may lead to weak bones or teeth.
2. It is the activator, cofactor or component of various enzymes: calcium activator of thrombin and zinc component of various enzymes.
3. Components of some substances with special physiological functions: iodine-thyroxine, iron-hemoglobin.
4. Maintain the body's acid-base balance and osmotic pressure of tissues and cells: maintain the body's acid-base balance through the proper coordination of acidic (chlorine, sulfur and phosphorus) and alkaline (potassium, sodium and magnesium) inorganic salts and the buffering effect of bicarbonate and protein; Inorganic salts and protein together maintain the osmotic pressure of tissues and cells; Lack of iron, sodium, iodine and phosphorus may lead to fatigue.
5. Maintaining neuromuscular excitability and membrane permeability: Potassium, sodium, calcium and magnesium are necessary conditions for maintaining neuromuscular excitability and membrane permeability.
6. Excessive intake of minerals is easy to cause overdose and poisoning. So we must pay attention to the proper intake of minerals.
7. Main minerals necessary for human body:
Calcium, magnesium, potassium, phosphorus, iron and zinc
Mineral deficiency:
1, iron: easy to cause iron deficiency anemia;
2, zinc: it has an impact on brain development;
3. Calcium: osteoporosis, hyperosteogeny, muscle twitching. At present, there are 109 kinds of diseases related to calcium, so I don't list them one by one.
4, iodine: deficiency dwarfism or thyroid edema, as well as hyperthyroidism.
Food sources of minerals:
Iron: animal liver, auricularia auricula
Zinc: oysters, rice and noodles.
Calcium: animal food, Chinese cabbage,
Iodine: algae, kelp, seaweed, etc.
dietary fibre
1, keep the digestive system healthy.
Step 2 strengthen the immune system
3. Reduce cholesterol and high blood pressure
4. Reduce insulin and triglycerides
5, laxative, diuretic, clearing the intestines and strengthening the stomach
6. Prevent cardiovascular diseases, cancer, diabetes and other diseases.
7. Balance hormones in the body and reduce hormone-related cancers.
Food source: leek, coarse grains, etc.
Water:
1, water participates in the whole process of metabolism in human body-water has strong solubility and ionization ability, which can make water-soluble substances in human body exist in dissolved state and electrolyte ion state; Because of its great fluidity, water can accelerate the transport of nutrients and the excretion of wastes in the process of digestion, absorption, circulation and excretion, so that metabolism and physiological and chemical reactions in the human body can be carried out smoothly.
2. Water is an important part of cells and body fluids-every cell and its basic unit of the human body contains water, and all kinds of gland secretions of the human body are liquids. If there is water shortage in the body, the secretion of digestive juice will be reduced, food digestion will be affected, appetite will decrease and blood flow will slow down. The accumulation of wastes in the body reduces metabolic activity, which leads to physical failure and aggravates the disease.
3. Water keeps a certain blood solubility in human body-the water content of human blood accounts for about 80%. If a large amount of water is lost, the blood solubility will decrease, which will lead to a decrease in blood pressure, thus affecting the functional activities of various organs of the human body, especially the heart, brain and kidney, so the blood solubility is closely related to the water content.
4. Water plays an important role in regulating human body temperature-the specific heat value of water is high, and it needs 1000 calories to increase or decrease10 degree per gram of water. Because the human body contains a lot of water, the resulting heat energy is absorbed by water during metabolism, so the body temperature will not increase significantly; Secondly, the evaporation value of water is large, and the heat of vaporization per milliliter of water is about 579.5 kcal. Therefore, as long as a small amount of water is evaporated, the human body can release a lot of heat to maintain a certain body temperature. For example, if the external environment temperature is high, human body heat can evaporate with water through the skin to maintain a constant body temperature.
5. Water plays an important role in lubricating human joints, muscles and body cavities-if human body lacks water, it will affect digestion and absorption, blood circulation, joint activity, body temperature regulation, body cavity organ function and waste metabolism, so water can play a role in buffering, lubricating and protecting various organs, joints, muscles and tissues of human body.
6. Water is one of the three magic weapons of medicine and medical treatment-medical infusion, blood transfusion and oxygen delivery. Especially for patients with high fever, diarrhea and dehydration, intravenous infusion is often used, and normal saline and necessary drugs are injected through intravenous vessels, which can quickly lead to the whole body, thus playing a role in bringing back the dead; General diseases are mostly caused by the invasion of various pathogens. After taking drugs to eliminate pathogens, pathogens, metabolic wastes and redundant drugs need to be discharged. Therefore, it takes a lot of drinking water to produce a lot of sweat and urine, and discharge dead pathogens, metabolic wastes and redundant drugs.
Hazard: Drinking too much water will change the blood salt concentration to a certain extent, thus promoting the change of fluid flow in the body, leading to brain swelling, skull compression and other symptoms, causing "water poisoning" and causing harm to the human body. Some athletes drink too much water after exercise, or some mental patients drink too much water to clean evil and toxins, which will cause "water poisoning"
The principle of drinking water:
1, drink water regularly and quantitatively, don't wait for thirst, drink 2500ml a day;
2. Drink water and drink naturally cooled boiled water (25 C);
3. Don't drink too much water before eating to prevent stomach acid from diluting and digesting nutrients;
4. Don't drink too much soup and drinks when eating to prevent it from affecting digestion;
5. Pay attention to drinking water hygiene: don't drink overnight water, repeatedly heated water or insufficiently heated water.