Salt is an indispensable condiment in daily life. Many people feel that eating too much salt is bad for the body and even control their salt intake. In essence, this is not wrong, but for the human body, a lack of salt is unacceptable. Today, let's understand why people need to eat salt and how to do it correctly.
Why do people need to eat salt
The "Seven Necessities" of opening the door: "Firewood, rice, oil, salt, sauce, vinegar, and tea," indicate that salt is a necessity for people. If you don't add a little salt to the dishes when eating, even the most delicacies will be as tasteless as chewing wax.
Why do people need to eat Salt is not only an important condiment but also a substance indispensable for maintaining normal human development. It regulates the balanced distribution of water in the body, maintains the osmotic pressure inside and outside cells, participates in the formation of gastric acid, promotes the secretion of digestive fluids, and can enhance appetite; at the same time, it also ensures the necessary pH for the action of pepsin, maintains the acid-base balance in the body, and the normal circulation of body fluids.
Humans cannot do without salt. Once the body lacks salt, it will lead to a low sodium content in the body, causing loss of appetite, limb weakness, and dizziness; in severe cases, it can even lead to nausea, loss of appetite, and accelerated heart rate.
So, how much salt does a person need every day? This depends on each person's age, physical condition, eating habits, and labor intensity. A normal person excretes about 380 milligrams of sodium daily from urine, skin, sweat, and feces. Converted to salt, this is less than 1 gram.
If a person consumes 4 grams of salt daily, it can show an effect on blood pressure. Therefore, everyone should not eat more than 4 grams of salt a day. However, it is not an easy task to change people's habit of consuming high-salt foods that has lasted for thousands of years.
Therefore, we must also be aware of the dangers of eating salt, not to eat salty foods, develop a low-salt habit in life, add oils and sour seasonings to food to make up for the blandness caused by the lack of salt.
Why humans cannot do without salt
Our body is like a water bag, with water accounting for about 60% of our body weight. About 8% of it is in the cardiovascular system, forming the plasma in the blood; 25% is in the spaces between tissues and cells, forming tissue fluid; the remaining 67% is inside the cells. These three parts are separated from each other by walls and cell membranes, but their water communicates with each other. Water diffuses from one part to another depending on which part has a higher salt concentration: water will automatically pass through a semi-permeable membrane from a low-concentration solution to a high-concentration solution until the osmotic pressure reaches equilibrium.
If you eat a very salty meal, the salt from the food is absorbed into the body and enters the blood, increasing the salt concentration in the blood. This breaks the osmotic balance, and water from the tissue fluid diffuses into the blood. As the water in the tissue fluid decreases, its salt concentration correspondingly increases, so water in the cells then diffuses into the tissue fluid. However, the cells have nowhere else to draw water from. As the water inside the cells gradually loses, the cells will wrinkle and shrink. Dehydrated cells cannot function normally, and in severe cases, they will die. Nerve cells in the brain are more sensitive to this, and once nerve cells dehydrate and die, they cannot be regenerated.
To avoid this consequence, you need to replenish water in a timely manner. By the time you drink water after eating a high concentration of salt, it is too late. Therefore, you must replenish water in time so that salt and water enter the body together.
After eating for about an hour, water and salt are absorbed from the intestines into the blood. If the food is very salty, the water you drink may not be enough, and the salt concentration in the blood will still increase. As long as the blood salt concentration increases by about 1%, the brain will sense it, and the pituitary gland will secrete "antidiuretic hormone" (ADH for short). It can change the permeability of the kidneys to water, increase the reabsorption of water by the kidneys, thereby temporarily reducing urine output to conserve water. Another effect of ADH is to make you feel thirsty. This is why if you eat a very salty meal, after an hour or two, you will feel thirsty again and want to drink water.
But after drinking so much water, our body's water bag becomes bloated. Although osmotic balance is maintained, water accumulates in the body, and blood volume increases, posing a risk of high blood pressure: blood vessels are a closed pipeline, and the more liquid inside, the greater the pressure. Therefore, food that is too salty cannot be compensated by just drinking more water; you should avoid eating too salty food from the beginning. The World Health Organization recommends that the daily salt intake for a healthy adult should not exceed 6 grams (equivalent to the capacity of a beer bottle cap), and it should be even lower for patients with high blood pressure. This includes the amount of salt consumed through various channels. In fact, the average person's salt consumption far exceeds this standard.
Consuming salt increases the salt concentration in the blood. Even without consuming salt, the loss of body water will also increase the salt concentration, which is the result of sweating. Sweat contains salt, but its concentration is lower than that of blood salt. If you sweat a lot during intense exercise or in hot weather, although you lose both water and salt at the same time, the proportion of water lost is higher than salt. The result is an increased blood salt concentration, stimulating the pituitary gland to secrete ADH, which makes you feel thirsty. To prevent dehydration, of course, you need to drink water. In cases of heavy sweating, you should also supplement the salt lost in sweat. Making your own saltwater to drink often results in a salt concentration that is too high, which has the opposite effect. It is best to make the saltwater concentration equal to that of sweat—that's how sports drinks are formulated. They are essentially sweat with sugar added.
How to eat salt
Zinc-added salt
Zinc is known as the "flower of life" and undertakes important physiological functions in the human body. It is a component of enzyme proteins and can promote the body's immune function and growth and development, protect the skin and vision, and maintain normal taste and appetite. Although foods such as animal offal, meat, eggs, and legumes are rich in zinc, people in rapid growth periods such as children, pregnant women, the elderly who eat less, and vegetarians may lack zinc in their bodies. Zinc-added salt is supplemented with a small amount of zinc sulfate or zinc gluconate to meet the needs of these groups.
It is a component of enzyme proteins Selenium-added salt
Selenium is called the "king of anti-cancer" elements in human trace elements by medical scientists. It can remove free radicals from the body, expel toxins, effectively inhibit the production of lipid peroxides, and enhance the body's immunity; selenium is also an important element for maintaining cardiovascular function, protecting the health of the cardiovascular system and myocardium. In addition, selenium can bind with heavy metals such as mercury, tin, thallium, and lead in the body to form metal-protein complexes for detoxification and detoxification. Selenium-added salt contains a certain amount of selenium compounds and is suitable for middle-aged and elderly people, patients with cardiovascular diseases, and other groups.
Riboflavin salt
Riboflavin, also known as vitamin B2, participates in the processes of biological oxidation and energy metabolism in the body. A lack of riboflavin in the human body affects biological oxidation, causing metabolic disorders, manifested as symptoms and diseases such as angular ulcers, keratitis, balanitis, blurred vision, and cataracts. Animal liver, kidney, egg yolk, green vegetables, legumes, and other foods contain relatively high amounts of riboflavin. For people whose diet is mainly plant-based, it may be advisable to eat some riboflavin salt. It can be seen that how to eat salt is not a small issue.
Iron-added salt
Iron participates in the transport of oxygen and tissue respiration in the body, maintains normal hematopoietic function, and is related to immune function. For special groups such as infants, women, and middle-aged and elderly people, who are prone to iron deficiency in their bodies, long-term consumption of iron-added salt can both season the food and meet their body's need for iron.
Low-sodium salt
The purity of sodium chloride in traditional salt is as high as 95% or more, while low-sodium salt replaces part of the sodium chloride with potassium chloride, with a sodium content of only 65% to 70%, which can effectively reduce the risk of suffering from cardiovascular diseases such as high blood pressure and heart disease. The content of magnesium and potassium in low-sodium salt is increased. Since potassium is also one of the essential trace elements for the human body, an appropriate amount of potassium helps lower blood pressure, and potassium chloride is also close to sodium chloride in taste. Low-sodium salt is mainly for special groups who need to restrict sodium salt due to kidney disease, high blood pressure, heart disease, etc. However, it should be noted that people with incomplete kidney function cannot excrete excessive potassium from the body, which will accumulate in the body and cause complications such as hyperkalemia, leading to adverse consequences. Therefore, even low-sodium salt should be eaten less by people with incomplete kidney function.
Traditional salt has a sodium chloride purity of over 95% Calcium-added salt
How to eat salt, especially calcium-added salt? Calcium is the main component of bones and teeth in the body. At the same time, calcium plays an important role in maintaining the activities of nerves and muscles, blood clotting, and the acid-base balance of body fluids. In children, calcium deficiency can cause rickets; in middle-aged and elderly people, it can easily lead to lumbar and leg pain, resulting in diseases such as osteoporosis (hyperplasia). Calcium-added salt is suitable for various groups that need to supplement calcium. Long-term use can maintain the balance of calcium in bones, blood, and cells in the human body and prevent various diseases caused by calcium deficiency. When eating calcium-added salt, you should also eat more foods rich in phosphorus, such as lean meat, eggs, nuts, peanuts, seaweed, kelp, fish, animal liver, black fungus, etc., to promote the absorption and full utilization of calcium.
Iodized salt
Iodine is of great significance to human health. It can synthesize thyroid hormones in the human body, which helps protein synthesis and nervous system development, promotes the metabolism of sugar and fat, and plays an important role in basic life activities such as water and salt metabolism and energy conversion. If iodine intake is insufficient for a long time, it is easy to develop goiter, also known as big neck disease. If a pregnant woman lacks iodine, it can hinder the development of the fetus, and if an infant lacks iodine, it can cause cretinism. At present, iodized salt is recognized worldwide as the most economical and effective fortified food for preventing and controlling iodine deficiency diseases. However, iodized salt is easily oxidized and decomposed, which makes the iodine ineffective. Therefore, iodized salt should be stored in a colored, sealed container in a cool and dry place, and do not buy too much at once. Because iodized salt will decompose and volatilize when exposed to high temperatures, salt should be added after the dishes are cooked when cooking. Try to avoid using iodized salt at the beginning of stir-frying, or for long stewing and boiling to reduce the loss of iodine.