In the process of studying the nutritional components of salt, dietary experts found such a strange phenomenon: residents living in mountainous areas such as New Guinea, Guizhou and Yunnan, as well as "indigenous people" living in islands and less civilized areas, have almost no high blood pressure, while people in the "taste-oriented" northern region often have a high incidence of high blood pressure.

What's going on here?

It turns out that this is all because the salt intake of southerners is very low, while the dietary taste of northerners is more biased.

The World Health Organization recommends that normal people's daily salt intake should not exceed 5 grams, and Chinese nutritionists recommend that it should not exceed 6 grams. In China, the average daily salt intake of northerners is 15 ~ 20g, and the prevalence of hypertension is 10%. The daily average salt intake of southerners is 12 ~ 13g, and the prevalence rate is about 5% ~ 7%.

The chemical name of salt is sodium chloride, and too much sodium salt is harmful to the prevention and treatment of hypertension. Researchers have done related animal experiments. Experiments have found that eating foods containing too much sodium can increase the blood pressure of animals, while limiting sodium can reduce blood pressure. Later, it was verified by medical clinic that about 20% ~ 60% of hypertensive patients received certain antihypertensive effect after adopting low-salt or salt-free diet.

Medicine also believes that people who eat 12 grams of salt every day have an average blood pressure of 20 mm Hg higher than those who eat less than 8 grams of salt every day. Why is the difference so big?

It is found that salt is easy to accumulate on the blood vessel wall. The greater the vascular resistance, the higher the blood pressure, and the heavier the load of internal organs such as heart and kidney, the normal metabolic function of the body will be disrupted, and the risk of edema, cerebrovascular accident or heart failure will be greatly increased.

When eating too salty, because the human body ingests a lot of salt, it first enters the blood circulation through the intestinal mucosa. The salt in the blood is high and needs to be diluted by absorbing water, so people will feel thirsty, so they drink a lot of water and the water enters the blood, which expands the blood volume. Then blood pressure will rise. It's not that people with high blood pressure can't drink water, but because if there is no excessive salt in the blood, water can't stay in it, and it will be excreted as urine through the kidneys soon, but the situation of high salt in the blood is different. Salt keeps water in the blood and raises blood pressure.

At present, a large number of studies have confirmed that salt restriction in traditional Chinese medicine can effectively reduce blood pressure and hypertension mortality. If 4 grams of salt is limited every day, about13 patients with moderate hypertension do not need to take medicine, and their blood pressure can reach the effective standard; Although the blood pressure of some people is not obvious, the symptoms such as headache and chest tightness are relieved and the blood pressure is stable; Moderate salt restriction (3 ~ 5g/ day) can enhance the effect of other antihypertensive drugs.

Here we suggest that patients with hypertension should control their salt intake below 3 ~ 4 grams per day. If it is mild or early, simple salt restriction may make blood pressure return to normal.

In addition, salt restriction is mainly to control the amount of salt used in cooking and table. If everyone eats 3 ~ 4 grams of salt every day, the sodium content is enough to ensure the normal needs of the human body; If everyone can control the daily intake of salt to 6-8 grams, that is to say, a family of three uses 500 grams or more of salt a month, it is more appropriate. This is not only beneficial to health, but also will not affect the delicious food.

In addition, nutritionists also suggest eating foods with high salt content as little as possible, such as pickled products, animal offal, clam shells, spinach and so on. Alkaline steamed bread also contains sodium, so you should eat more cereals and fruits because it contains less sodium. If you need to supplement potassium, you can eat more foods containing more potassium, such as kelp, laver, fungus, yam, banana, potato, fish, tomato, dried mushrooms and so on. Eating "low sodium salt" and "health salt" with low sodium and high potassium can play a dual role in limiting salt and supplementing potassium.

Eating too much salt can easily lead to respiratory diseases.

According to the survey of epidemiologists, the sales volume of salt is directly proportional to the local mortality rate of bronchial asthma, which means that the more salt you eat, the higher the morbidity and mortality rate of bronchial asthma. Why is this happening?

Medicine believes that: first of all, high-salt diet reduces oral saliva secretion, which is conducive to the breeding of various bacteria and viruses in the throat. Secondly, high salt will kill the normal parasitic flora of the upper respiratory tract, leading to flora imbalance and disease. Finally, high-salt diet will inhibit the proliferation of mucosal epithelial cells and make them lose their disease resistance. These factors will reduce the ability of upper respiratory mucosa to resist disease invasion, and all kinds of bacteria and viruses can easily take advantage of it.

In addition, if we eat too salty, high concentration of sodium in the blood is prone to bronchitis, which will make the bronchi contract more easily, thus leading to the secretion that is not easy to eliminate and breeding bacteria. Eating too much salt can also induce asthma attacks. If a person eats too much salt, he is not only prone to high blood pressure, but also increases the incidence of asthma.

After studying influenza in recent years, medical scientists found that the susceptibility of human body to influenza is related to salt intake. So what's the relationship between salt and flu?

It turns out that high concentration of sodium salt has a strong osmotic effect. On the one hand, it can kill bacteria or inhibit the growth and reproduction of bacteria, but it also affects the defense function of human cells. If a person consumes too much salt, it can reduce saliva secretion and lysozyme in the mouth, making it easier for the virus to establish itself in the upper respiratory mucosa.

In addition, the penetration of salt inhibits epithelial cells, greatly weakening or losing the disease resistance including interferon secretion; The neuraminidase of influenza virus acts on mucopolysaccharide on the cell surface and invades the cell, which makes the throat mucosa lose its barrier function and makes other viruses and bacteria "enter". At this time, pharyngitis, tonsillitis and other upper respiratory tract inflammation also appeared.

Little knowledge:

Nutritionists suggest that children aged 1 ~ 6 should not eat more than 2 grams of salt a day; Before 1 year-old, it is advisable not to exceed 1 gram every day. In order to control children's salt intake, it is suggested to use the method of "adding salt at meals", that is, no salt is added when cooking, and then salt is added when the dishes are cooked. Because salt is put at this time, the salt mainly adheres to the surface of food and dishes, and it is too late to penetrate into the interior, while the taste of people mainly comes from the surface of dishes. Just add a little salt, it's salty enough to eat.

Salt will make your bones lose.

According to the statistics of the American Osteoporosis Foundation, about 8 million women in the United States suffer from osteoporosis, and the number of people who die from osteoporosis and other diseases is as high as 7? Twenty thousand people. Nutritionists believe that sodium usually causes women to lose about 1% of their bones every year.

How can seemingly insignificant salt have such great power?

The content of sodium, the main component of salt, is about 40%, which can be said to be the direct killer of bone loss in human body. Generally speaking, human kidneys excrete used sodium with urine every day, but for every 65,438+0,000 mg of sodium excreted, it also consumes about 26 mg of calcium. This seems to have no effect, but the more sodium the human body needs to excrete, the greater the consumption of calcium, which will eventually affect the calcium necessary for bone health.

Too much sodium in diet can make too many sodium ions compete with calcium ions when renal tubules reabsorb, and the excretion of calcium increases, which stimulates parathyroid gland to secrete more parathyroid hormone, thus activating adenylate cyclase on osteoclast membrane, promoting the dissolution of calcium in bone, destroying the dynamic balance of bone calcium metabolism, and easily leading to calcium deficiency, osteoporosis and even fractures.

At the same time, too much salt will increase the burden of renal excretion and stimulate the excretion of calcium. Excessive calcium excretion will lead to osteoporosis and urinary calculi, because salt will increase the excretion of calcium and oxalic acid from urine and form calcium oxalate calculi. In addition, eating too salty directly affects children's absorption of zinc, leading to zinc deficiency in children, which will also reduce immunity.