The human body must take a certain amount of nutrients from food. Insufficient or excessive intake will lead to metabolic disorders or diseases. Only when the intake of nutrients is complete, sufficient and appropriate, can all kinds of nutrients be in a balanced state in the body, interact with each other, form an orderly chain connection, and maintain the vitality of the body.
If you take too few nutrients for a long time, it will destroy the nutritional balance in the body, have a negative impact on physiological functions, and even cause diseases. For example, if the body lacks vitamin A for a long time, the eyes will feel dry, photophobia, tears, blurred vision, night blindness and corneal softening; If the body lacks vitamin B 1 for a long time, it will cause indigestion, numbness of hands and feet, polyneuritis and beriberi; If the body lacks vitamin C for a long time, the gums will swell and bleed easily, and the wound will not heal easily. In severe cases, you will suffer from scurvy; Long-term calcium deficiency in the body will cause osteoporosis and rickets in children; If the body lacks magnesium for a long time, it will cause arterial spasm, which will easily lead to cardiac arrest and sudden death; If iron deficiency occurs in the body for a long time, anemia will occur, which will affect the function of the immune system; If the body lacks copper for a long time, it will affect the nervous system and cause cardiovascular rupture; If the body is short of zinc for a long time, it will increase the susceptibility of esophageal cancer; If the body lacks iodine for a long time, it will cause insufficient thyroid secretion, fatigue, slow thinking and goiter; If the body lacks sulfur, nickel and B vitamins for a long time, it will have a negative impact on pancreatic vitality. ...
If you consume too many nutrients for a long time, it will also destroy the nutritional balance in the body, make metabolism disorder and cause diseases. For example, if you eat too much fat for a long time, it will make you obese and cause heart disease, colon cancer and breast cancer. If you consume too much protein for a long time, it will increase the burden on the kidneys, and too much uric acid in the blood will damage the enamel of teeth, the luster of teeth will disappear, gray spots will appear, and bone and kidney diseases will appear; If you consume too much copper for a long time, it will accelerate the decomposition of iron stored in the body, and the protein effect of plasma iron transfer will be negatively affected, which will increase the excretion and decomposition of iron, thus reducing the iron content in the body and causing anemia; If you take too much iodine for a long time, it will unbalance the regulation of water and body temperature in the body and cause hyperthyroidism. ...
In addition to a certain amount of nutrients, the human body should take them in an appropriate proportion. Nutrients taken from the diet can only maintain the nutritional balance in the body and help maintain vitality, such as protein, fat, carbohydrates, etc., so we should take them in a certain proportion. The ideal ratio proposed by the World Health Organization is that 30% of heat energy is supplied by fat, 12% by protein and 58% by carbohydrate. There is another ratio: carbohydrate accounts for 68% of total calories, fat accounts for 20%, and protein accounts for 12%. No matter which proportion, there is a certain truth, which shows that taking various nutrients from the diet can only contribute to good health if it is taken in a certain proportion.
As for protein, the human body basically needs two things: one is to maintain nitrogen balance, and the other is to supply heat energy. Protein is the material basis of human body, and muscles, hair, skin, blood and enzymes are all made of protein or protein is one of its main components. The main function of protein in human body is to ensure the growth, renewal and repair of cells, and to maintain the nitrogen balance of human body, while the heat energy provided by protein is in a secondary position, so the proportion of heat energy provided by protein is the smallest. In other words, in addition to maintaining nitrogen balance, the protein intake should only be enough to supply 12% of calories.
With regard to fat, under normal physiological conditions, fat is directly stored in fat cells in the body after being ingested, that is, it is directly converted into body fat, which provides about 20% ~ 30% heat energy for the human body. If you eat too much fat for a long time, you will gain weight and become fat.
As for carbohydrates, they are stored in the muscles, brain cells and liver of the whole body in the form of glycogen, which directly provides heat energy for the body, so we should take more. Among protein, fat and carbohydrate, carbohydrate intake should be the largest.
The proper proportion of nutrients is also reflected in many aspects, such as protein in diet. Only by matching in proportion can we receive ideal nutritional value. Protein can only be absorbed when it is decomposed into amino acids in gastrointestinal tract, and it can be used as a raw material to synthesize human protein. In other words, the human body's need for protein is actually the need for amino acids. The human body needs more than 20 kinds of amino acids to synthesize protein, and the proportion of each amino acid is certain. If any required amino acid exceeds the required proportion, the excess will not participate in the synthesis of protein. If the ratio is lower than required, protein will be synthesized according to this minimum value. For example, the synthesis of myoglobin in human body only needs 9.5% lysine, and the excess part is not only useless for the synthesis of myoglobin, but also hinders the intake of arginine, which can promote the secretion of growth hormone by pituitary gland. It can be seen that the types and proportions of essential amino acids in the diet are complete, far more important than the absolute amount.