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In order to survive and develop, human beings must ingest food, and the useful ingredients in food are called nutrients. Nutrition is an important material basis for the growth and development of tissues and cells, tissue repair and renewal, organ protection, production of various body fluids and metabolic regulation.
The nutrients needed by human body can be summarized as protein, lipids, carbohydrates, inorganic salts, vitamins, dietary fiber and water. If one or more nutrients are often lacking in daily life, it will affect your health.
The life activities of human body need energy, which is called heat energy. The energy-producing nutrients in food are carbohydrates, fats and protein. If the human body's long-term heat intake is insufficient or excessive, it will bring harm to health. According to the standards recommended by the Nutrition Society of China, the daily supply of adult males is 10000 joules-16750 joules, and that of adult females is 92 10 joules-0/4235 joules.
1. protein
Protein is the material basis of life. It consists of many kinds of amino acids, such as carbon, hydrogen, oxygen, nitrogen, sulfur, etc., and there are more than 20 kinds of amino acids that make up protein. Protein's function is to form cells and tissues of the body, promote growth and development, participate in substance metabolism, form antibodies, enhance immunity and supply heat energy. Each gram of protein can provide 16.75 joules of heat energy.
The supply of protein depends on different ages, living and working environments. Under normal circumstances, the daily weight of an adult is 0.8g-1g. If the intake of plant protein is the main factor, it can be increased appropriately. Generally speaking, for an adult male aged 18-40, the daily protein supply should be 70g- 105g. 18-40 adult female, weighing 53kg, the daily protein supply should be 60g-85g.
2. Carbohydrates
It is an organic compound composed of carbon, hydrogen and oxygen. Carbohydrate mainly supplies heat energy and is the main nutrient of human energy. The heat production per gram of carbohydrate is 16.75 joules.
3. Lipids
Fat is composed of carbon, hydrogen and oxygen, and triglycerides composed of fatty acids are the main form.
Phospholipids and cholesterol are both lipids. Phospholipids are composed of fatty acids, phosphorus and nitrogen, and are important components of all cells. Phospholipids play an important role in body fat metabolism. Cholesterol is an important part of the body. Too much or too little cholesterol intake is not good for health.
The main function of lipids is to supply heat energy. Every gram of fat produces 37.68 joules of heat, which is the nutrient with the highest heat production. It can promote the absorption of fat-soluble vitamins, maintain body temperature, protect organs, supply essential fatty acids, improve food taste and stimulate appetite. The supply of fat can vary according to age, labor intensity and weight. And the average adult's daily intake is 0.8 g/kg body weight.
4. Inorganic salts
Also known as minerals, it is the tissue component of human body. Among them, macro elements with more inorganic salts are needed by human body, such as calcium, phosphorus, potassium, sodium, magnesium, chlorine and sulfur. Only trace or extremely trace elements are called trace elements, such as iron, iodine, copper, zinc, selenium, molybdenum and so on. Inorganic salts cannot be synthesized in the body and must be taken from food.
The role of inorganic salts is to participate in the formation of bones, teeth, muscles, glands, blood, enzymes, hair and other tissues, regulate the physiological functions of the human body, maintain osmotic pressure, maintain acid-base balance and maintain the normal beating of the heart. It is an extremely important nutrient for human body. If some trace elements are lacking, it will lead to the decline of immunity and induce related diseases.
5. vitamins
There are many kinds of vitamins, which can be divided into fat-soluble vitamins and water-soluble vitamins. Vitamins A, D, K and E are fat-soluble vitamins. Vitamins c, b, d and folic acid are water-soluble. Most vitamins cannot be synthesized in the body and must be taken from food.
Vitamins do not provide calories in the body, nor do they form tissues. Their main functions are to regulate physiological functions, enhance immunity and synthesize coenzyme. The demand of vitamins in the body is very small, expressed in milligrams or micrograms, but it plays a very important role in the growth, metabolism and physiological functions of the body. Lack of one or more vitamins can cause vitamin deficiency or other related diseases.
6. Edible fiber
It can be divided into soluble fiber and insoluble fiber. Pectin, seaweed and bean gum in food are all soluble fibers. Crude fiber, semi-fiber and lignin are insoluble fibers.