Salt is the "king of all flavors," an indispensable and important condiment in people's lives, and also the main source of chlorine and sodium in the human body. However, since chlorine and sodium are widely found in animal and plant foods such as meat, fish, eggs, vegetables, and fruits, the normal diet generally lacks little sodium. According to the estimation of the Food and Nutrition Board of the U.S. National Academy of Sciences, the adequate daily intake of sodium for adults is 1100-3300 milligrams. In this way, the daily intake from natural foods is sufficient to meet the human body's need for sodium, that is, to maintain the normal metabolism of sodium in the body, without the need to add more salt. However, because people are accustomed to using salt in their daily lives, it is not practical to completely avoid it. The problem is that the current amount of salt people use far exceeds their physiological needs. According to the results of the 1982 national nutrition survey and epidemiological investigations in China, it was found that the average daily salt intake of Chinese residents is about 10-15 grams, and a certain relationship was found between salt intake and the incidence of hypertension.
Excessive salt intake can have more adverse effects on the elderly and people with heart disease, hypertension, kidney disease, cirrhosis, or ascites. Therefore, Chinese nutritionists recommend that the daily salt supply per person should be 8-10 grams, while the American Longevity Society suggests it could be reduced to 2-4 grams. Due to long-term eating habits, people's tastes vary, some "light" and some "heavy," but this is not a physiological need. For the sake of health and longevity, the elderly should control their salt intake according to their individual conditions. For example, those with heart, kidney, or liver diseases can follow medical advice and the guidance of nutritionists to adopt a low-salt diet, consuming only 2-4 grams of salt per day; or a salt-free diet, which means no salt is added to the diet; or a low-sodium diet, which limits the consumption of certain high-sodium foods, such as pickles, dried noodles, fried dough sticks, dried small shrimp, cabbage, spinach, celery, and amaranth.
As early as ancient times, humans knew that excessive salt intake was harmful to the body. The ancient Chinese medical classic "Neijing" (The Yellow Emperor's Inner Canon) records that "excessive consumption of salty food will constrict the meridians and change the complexion."
The famous Tang dynasty physician Sun Simiao also said: "Excessive salt shortens one's life." This shows that the ancients had long been aware of the harm of overly salty substances to the human body. Many famous Chinese physicians believe: salt enters the kidney meridian; in moderation, it can tonify the kidneys and strengthen bones, which is essential for people. However, excessive consumption damages the kidneys, leading to premature aging. Therefore, it is emphasized that in daily diet, "the flavor should be moderate and not too salty," especially for soups, which should be light and delicious.
In summary, eating less salt is beneficial for preventing hypertension, myocardial damage, and cerebrovascular accidents. Therefore, the saying "less salt leads to a longer life" has a certain scientific basis.