The zero nitrogen balance reflects the relationship between nitrogen intake and nitrogen discharge. Nitrogen balance includes zero nitrogen balance, positive nitrogen balance and negative nitrogen balance.
Nitrogen balance is the dynamic balance of protein decomposition and synthesis in the body, which is measured by the amount of nitrogen absorbed and discharged by the body. Under normal circumstances, the adult's body no longer grows, and the daily intake of protein decomposes to meet the needs of tissue protein renewal, and at the same time produces energy and nitrogen-containing waste (discharged with urine), which shows that nitrogen intake and discharge are roughly equal, which is called total nitrogen balance (or total nitrogen balance).
Healthy adults maintain zero nitrogen balance and are 5% richer. If nitrogen intake exceeds nitrogen excretion, it is a positive nitrogen balance, that is, B >; 0, children in the growth and development stage, when women are pregnant, when they are recovering from diseases, and when exercise and labor need to increase muscles, they should ensure proper positive nitrogen balance to meet the extra needs of the body for protein.
When nitrogen intake is less than nitrogen discharge, it is negative nitrogen balance, that is, B.
Importance of nitrogen balance:
"Nitrogen Balance" is used to measure the protein requirement of human body and evaluate the protein status of human muscles. Protein is decomposed into amino acids and small peptides in the digestive tract and absorbed. Most of them are used to synthesize tissue proteins, repair and grow damaged muscle tissues after exercise, and some of them are used to synthesize various functional proteins and other nitrogen-containing compounds, such as purine and creatine. After a small amount of amino acids are absorbed, they are decomposed in the body for energy supply.
Under the condition that the body does not consume protein at all, the protein in the body is still decomposed and synthesized. A 60kg adult man still excretes 3.2g nitrogen in his daily metabolism, which is equivalent to 20g protein. This inevitable consumption of nitrogen without intake of protein is called "necessary nitrogen loss". In other words, an adult male weighing 60kg should consume at least 20g of high-quality protein every day. Maintain normal protein metabolism in the body. ?