Nutrition and physiological function of water: Life comes from water environment. Without water, there would be no life on the earth. More than 60% of human body weight is water, and all living cells and physiological and metabolic activities are inseparable from water. Because water is widely available, its composition is relatively simple, and it does not produce energy, so many people think that water itself has no nutritional value, and even some food experts have this view. But from the concept of nutrition, water is the most important nutrient. The main nutritional and physiological functions of water are as follows. 1. Water is the transport medium of nutrients and metabolic wastes in the body. The nutrient supply and metabolites of each cell and tissue are transported through the blood circulation system and lymphatic system, and water is the main component. Not only amino acids, glucose, minerals and many other water-soluble components are transported by water, but also the surface of lipids is generally wrapped by some water-soluble protein, so they can travel freely in the blood system and lymphoid tissues. In this respect, water is both a solvent and a detergent in the body. Nitrogen-containing wastes produced by protein metabolism can be dissolved in blood. The kidneys can filter these wastes out of the blood and excrete them together with water in the form of urine. 2. Water directly participates in human metabolism. Almost all physiological and biochemical metabolic reactions in human body need to be carried out in water environment. For example, the amount of water in cells will not only affect the activity and reaction rate of enzymes, but also change the reaction direction. At the same time, water is also the substrate or product of some reactions. 3. Lubricants, chemical buffers, physical buffers and coolants. Another important characteristic of water is incompressibility, so water can play the role of lubrication and buffering in joints, provide shock protection for spinal cord and maintain the normal pressure of retina and lens in eyeball. Water is also a lubricant for the digestive system and all other mucous tissues. Water is the coolant for regulating body temperature. In a high temperature environment, human body water evaporates in the form of sweat, which will take away a lot of heat and lower the body temperature. Water is the source of many trace elements. Therefore, it is very important to ensure adequate water intake to maintain normal physiological functions of the human body. The amount of drinking water needed by each person every day should be balanced with the amount of water lost, which changes due to changes in activities, environment and diet. Normal people should drink more water, and don't wait until they are thirsty, which is beneficial to health. For patients with heatstroke, kidney calculi's disease, constipation, fever and other diseases, it is very helpful to increase drinking water in moderation to alleviate the disease. Jiang Weibo made a systematic analysis and summary of drinking water and health and safety, which will be published in recent bloggers, including the following contents: * Investigation case analysis-celebrities who died of water poisoning *