The normal life activities of the human body are maintained by nutrients, also known as nutrients, which can provide the materials and energy needed for human growth, health maintenance and life and labor. The source of nutrients is usually obtained by eating food, and the nutrients in these foods can only be utilized after being eaten, digested and absorbed by the human body.
At present, more than 40 known nutrients can be roughly divided into six categories, namely: protein, fat, carbohydrates, vitamins, inorganic salts and water. The main functions of nutrients are: (1) main heat energy, which provides heat for human body, such as carbohydrate, protein, fat, etc. (2) It is helpful for human growth and development, and can construct various parts of the body, such as water, inorganic salts, fat, protein, carbohydrates and vitamins. (3) It can regulate essential physiological mechanisms of human body, such as water, vitamins, inorganic salts, fat, protein, etc.
protein
From single cells to complex human organs, protein is the basic substance, and protein is the foundation of life. Protein mainly exists in human muscle tissue, and the rest exists in blood, skin, soft tissue, hair, bones and teeth, accounting for about one third of these tissues. The heat supply in protein accounts for 10% of the total energy required by human body. Therefore, adults need to consume 70-80 grams of protein every day, while developing teenagers need to consume 80-90 grams. Protein is rich in animal foods, such as meat, eggs, fish and plant foods, such as beans.
fat
Fat is an important part of human body, which is divided into lipid and neutral fat. Lipids include phospholipids and cholesterol, and neutral fats, also known as triglycerides, are widely distributed around the skin, abdominal cavity, organs and muscle space. Fat accounts for about 13% of human body weight, and women are higher than men.
The heat production of fat accounts for 16%-20% of the total energy required by human body, and the daily requirement of adults is 50-70g. Eating too much will increase the burden on the digestive system and make it easy to suffer from obesity and cardiovascular diseases. The sources of fat mostly come from milk, egg yolk and plant seeds, such as peanuts, soybeans, sesame seeds, walnuts and other foods.
carbohydrate
Carbohydrate, also known as sugar, is a component of the human body. It is the main source of human energy and plays an obvious role in maintaining health. Adults have about 65,438+0,000 grams of carbohydrates. Carbohydrate is the most effective and economical energy source for human body. Heat can be generated half an hour after a meal, which is the main energy source of the human body. The average adult needs 480-600 grams of carbohydrates every day. Cereals, potatoes, beans, sugars, fruits and vegetables in food are the main sources of carbohydrates.
vitamin
Vitamins are essential for maintaining life and low-molecular-weight organic compounds necessary for maintaining human life and health. Some vitamins are some enzymes and important components in the body, and enzymes are catalysts for biochemical reactions. Therefore, without vitamins, there would be no human life activities.
Vitamins not only participate in the most basic metabolic activities of the human body, but also enhance the anti-inflammatory, disinfection and detoxification functions of the body, which can improve the body's ability to resist diseases.
mineral salt
Inorganic salts, also known as minerals, are composed of inorganic elements, accounting for 4% of human body weight. Due to the different contents of inorganic salts in human body, it can be divided into macro elements and trace elements. There are seven elements: calcium, phosphorus, sulfur, potassium, sodium, chlorine and magnesium, which are abundant in the body. Trace elements include iron, copper, zinc, iodine and selenium. These are relatively few in the human body.
Inorganic salts have many functions in human body. It builds human tissues, makes bones hard and supports the body. At the same time, it exists in cells, blood, nerves, muscles and other tissues, forming the soft tissue of human body. Inorganic salts can be dissolved in body fluids, which can strengthen various physiological functions of the human body and keep the human body in a relatively balanced state.
The supplement of inorganic salts also comes from daily diet.
water
The water content in the human body accounts for about 60% of the body weight, which is distributed in various tissues, organs and body fluids of the human body, excreted through the skin and urine, and constantly absorbed from the outside to supplement, so as to maintain the balance of water in the body.
If protein is the foundation of life, then water is the cradle of life. Because water is the solvent of nutrients, the solvent of metabolites and the medium of all reactions in the body. The digestion and absorption of nutrients, the exchange of substances, the circulation of blood, the synthesis of new tissues and the excretion of waste and toxic substances are all inseparable from water. In addition, water can lubricate joints, muscles and body cavities, keep skin soft, regulate human body temperature and protect human tissues and organs. Ordinary adults need 2000-3000 ml of water every day, and they can get enough water through food and drinks.