Why is water so important to us? Macroscopically, the digestion of food, the regulation of body temperature and the excretion of metabolites all need the participation of water. From the microscopic level, normal biochemical reactions, the dissolution and transportation of substances, and the regulation mechanism of neurohumors are also inseparable from water. Therefore, body fluids with water as the main component account for 60% of our body weight. Although water is very important to us, it needs to be balanced. Too much or too little water will bring adverse effects: too much water may cause blood pressure rise, systemic edema, hyponatremia and other reactions, and too little water may cause blood pressure drop, listlessness, kidney damage and other manifestations. Seeing this, some friends may worry: does this mean that drinking too much water or drinking too little water is not good? Don't worry for the time being, because our kidneys will solve the problem.
The kidney has a very important function: filtering our blood can discharge useless, redundant or harmful substances, including excess water, to purify the blood. But this work is not a task that can be completed over and over again, but needs to be carried out all the time, day and night. Every hour, our kidneys filter blood 12- 15 times to create a healthier and more stable internal environment. Then the problem comes: the water we drink is mainly distributed in the blood. If we drink more water, shouldn't the kidneys need to filter blood more often? Will this increase the burden on the kidneys? No, besides filtering blood, the kidney has two important functions: reabsorption and concentration.
There are three important "workshops" in the kidney, namely glomerulus, renal tubule and collecting duct. Among them, blood filtration is mainly carried out in the glomerulus, but the original urine produced by glomerular filtration is as high as 180L, and our total blood volume is only 4-5L, so the original urine filtered by glomerulus will not be directly excreted, otherwise we would have been squeezed dry. Before urine is formed and excreted, the original urine will pass through two "workshops" in turn: in the renal tubules, 99% of the useful substances in the original urine will be absorbed into the blood again. In the collection tube, the human body will secrete a substance called "antidiuretic hormone" according to the osmotic pressure and blood volume of the crystal, and concentrate the urine:
After drinking a lot of water, our crystal osmotic pressure will drop slightly and our blood volume will increase slightly. At this time, although the total amount of blood filtered by glomerulus will increase, it will not increase the workload per unit time, but reduce the reabsorption of urine by renal tubules and collecting tubes and increase the total amount of urine excreted. More importantly, each kidney has about 6.5438+0 million nephrons (composed of glomeruli and renal tubules), and they also have a reasonable working system, which will take turns to work and rest, and the kidneys will not be damaged due to overwork. Therefore, increasing the amount of drinking water properly will not harm the kidneys. So, can drinking more water protect the kidneys? Water is an important solvent. Most useless, redundant and harmful substances in the human body need to be dissolved in water before they can be excreted through urine. If you drink less water, these substances will accumulate in the body or in the kidneys, which may damage the kidneys and make it easier to form stones.
Therefore, increasing the amount of drinking water has a certain protective effect on the kidneys, but this does not mean that the more water you drink, the better the kidneys. The so-called protective effect is limited by preconditions: compared with people who drink less water, the kidneys are healthier. This is true for healthy people, and people with kidney damage have reached similar conclusions. Related studies have found that compared with people who drink less water, increasing drinking water appropriately can delay the decline of renal function, which may be related to the decrease of antidiuretic hormone secretion. The antidiuretic hormone can not only concentrate urine and regulate blood volume in kidney, but also act on blood vessels to raise blood pressure. For people with kidney damage, excessive secretion of antidiuretic hormone may accelerate the decline of renal function. Therefore, drinking water in moderation is beneficial to the kidneys. Of course, if the function of the kidney has been seriously reduced, it is necessary to reduce the amount of drinking water, otherwise it will aggravate the damage to the heart and blood vessels.
So, how to drink water is healthier? First of all, we should control the investment reasonably. The human body will lose water in many ways. Breathing and sweating may lose 800 to 1000 ml of water, urine will excrete 1000-2000 ml of water, and stool also contains 100-200 ml of water, which may lose more than 2000 ml of water every day on average. However, this does not mean that we need to replenish more than 2000 ml of water. This is because our own metabolism will produce 300 ml of water, and food also contains hundreds of thousands of ml of water. Therefore, on the whole, it is reasonable for ordinary people to keep the daily drinking water between 1.500- 1.700 ml, which is more conducive to kidney health. Of course, if you have strenuous exercise, excessive sweating, severe vomiting or diarrhea, you need to increase your water intake. If you are complicated with metabolic diseases such as hyperuricemia, you need to increase the amount of drinking water, 2000-3000 ml per day, to reduce the deposition of uric acid in the kidney and reduce the risk of uric acid nephropathy.
Secondly, we should choose the right one. Drink boiled water first, and try to drink less sugary drinks. The influence of boiled water on metabolism is neutral, and excessive intake of sugary drinks (with added sugar content above 5%) will increase the risk of obesity, diabetes and cardiovascular diseases. Although some drinks do not contain added sugar, if they contain more artificial flavoring agents, they will also increase the risk of coronary heart disease and stroke. In addition, drink less fructose-rich drinks, especially carbonated drinks and fruit juice, which will inhibit uric acid excretion, especially in patients with hyperuricemia.
On the contrary, the intake of milk, light tea and coffee can be increased appropriately. Many studies show that increasing the intake of dairy products, including yogurt, can not only provide rich protein and calcium, but also reduce the risk of hypertension, diabetes and ischemic stroke, but it should not be too much, and it is appropriate to 150-300ml per day. In drinking tea, drinking 50-250g of tea every month, especially green tea, can also reduce the risk of metabolic diseases and cardiovascular diseases, but it is not recommended to use strong tea as light tea, otherwise it will affect the absorption of iron, reduce the quality of sleep, and even induce gastric mucosal damage. As for coffee, studies from western countries show that drinking 1-4 cups of coffee every day has a protective effect on cardiovascular system, but stay away from dinner for more than half an hour, otherwise it will affect the absorption of calcium, iron and vitamins in food.
Finally, emphasize the distribution of drinking time. After drinking water, the human body does not store excess water in the body, but gradually excretes it. Take drinking 1000 ml water (two bottles of mineral water) as an example, the human body will discharge the excess water in time within 2 hours, so it is not recommended to drink a lot of water at a time, and it is advisable to drink a glass of water at a time to replenish the water lost at night and dilute the blood. Drinking plenty of water before going to bed is not recommended, especially for the elderly. The concentration function of kidney decreased, resulting in nocturia. Drinking water before going to bed may increase the number of nocturia and reduce the quality of sleep. There should be at least two hours between drinking water and sleeping. Try to drink less tea and coffee before going to bed, especially those who are sensitive to caffeine, otherwise it will increase the excitability of the nerves and may be difficult to fall asleep at night. Tea, coffee and sleep should be separated by at least four hours, which can reduce the impact.
To sum up, water is an important part of human body, and kidney is an important organ to regulate water balance. The water we drink is filtered by the glomerulus, reabsorbed by the renal tubules, concentrated by the collecting tube, and then excreted in the form of urine. After drinking plenty of water, the concentration and reabsorption of urine will be reduced, maintaining the stability of the internal environment, so the kidney will not be damaged by increasing the workload of glomerulus. Compared with people who drink less water, it is useless to drink water in moderation. Healthy drinking water needs to be controlled reasonably, and the daily drinking amount should be 1500- 1700 ml. In case of hyperuricemia, the amount of drinking water should be increased, and in case of severe renal damage, the amount of drinking water should be reduced. Give priority to boiled water and drink less sugary drinks rich in artificial sweeteners and fructose, which can appropriately increase the intake of milk, coffee and light tea. Drinking a lot of water at a time is not recommended. You can drink a cup of warm water in the morning and try to avoid drinking water before going to bed, which is more beneficial to your health.
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