The relationship between salt and human health

Table salt, also known as table salt, is one of the most important substances for human survival and the most commonly used seasoning in cooking. The main chemical component of salt, sodium chloride (chemical formula NaCl), has a content of 99% in table salt. Potassium chloride is added to table salt produced in some areas to reduce the content of sodium chloride and reduce the incidence of hypertension. At the same time, table salt in most parts of the world is added with iodine to prevent iodine deficiency diseases. Table salt with added iodine is called iodized salt.

Salt is indispensable in people's lives. The total amount of sodium ions contained in the adult body is about 60 g, of which 80% is present in extracellular fluid, that is, in plasma and intercellular fluid. Chloride ions are also found mainly in extracellular fluid. The physiological functions of sodium ions and chloride ions mainly include the following points:

1. Maintain the osmotic pressure of extracellular fluid

Na and Cl are the main ions that maintain the osmotic pressure of extracellular fluid ; K and HPO4 are the main ions that maintain the osmotic pressure of intracellular fluid. Among the total cations in the extracellular fluid, Na accounts for more than 90%, and among the total anions, Cl accounts for about 70%. Therefore, salt plays an important role in maintaining osmotic pressure and affects the movement of water in the human body.

2. Participate in the regulation of acid-base balance in the body

Sodium bicarbonate formed from Na and HCO3 has a buffering effect in the blood. There is also a balance between Cl and HCO3 between plasma and red blood cells. When HCO3 penetrates from the red blood cells, the anions in the red blood cells decrease, and Cl enters the red blood cells to maintain the electrical balance. Vice versa, the same is true.

3. Chloride ions participate in the generation of gastric acid in the body

Gastric juice is highly acidic, with a pH of about 0.9 to 1.5. Its main components are pepsin, hydrochloric acid and mucus. Parietal cells in the corpus gastric glands secrete hydrochloric acid. Parietal cells transport HCO3 into the blood and secrete H into the gastric juice. At this time, Cl enters the gastric juice from the blood through the parietal cells to maintain electrical balance. Why can such strong hydrochloric acid not corrode the stomach wall in the stomach? Because there is a kind of mucus cell in the gastric body gland, the secreted mucus forms a layer of mucus about 1 mm to 1.5 mm thick on the surface of the gastric mucosa. This mucus layer is often called the barrier of the gastric mucosa. Under the attack of acid, The gastric mucosa will not be digested by digestive enzymes and form ulcers. However, drinking alcohol will weaken the barrier function of the gastric mucosa, often increasing the possibility of causing gastric ulcers.

In addition, salt also plays a role in maintaining the normal excitability of nerves and muscles. When a large amount of extracellular fluid is lost (such as excessive bleeding, excessive sweating) or there is a lack of salt in the food, the content of sodium ions in the body is reduced, and potassium ions enter the blood from the cells, resulting in thickening of the blood, oliguria, and yellowing of the skin. and other diseases. The human body's requirement for salt is generally 3 g to 5 g per person per day. Due to different living habits and tastes, the actual salt intake varies greatly from person to person and from place to place. The average person in my country consumes about 10 g to 15 g of salt every day.

Instructions for consumption

1. Buy less and eat promptly

Buy small amounts and then buy after eating to prevent the volatilization of iodine. Because potassium iodate will decompose and volatilize under conditions of heat, light, wind, and humidity.

2. Avoid high temperatures

When cooking and making soup, avoid adding iodized salt at high temperatures. When stir-frying, add iodized salt to the pot, and the iodine consumption rate is only 10. If you put iodized salt in the middle, the consumption rate will be 60;

3. Avoid long-term storage in open containers.

If iodized salt is in contact with sunlight and air for a long time, iodine will easily volatilize. It is best to put it in a colored glass bottle, seal it tightly after use, and store it in a sealed container.

4. Avoid adding vinegar

Iodine will be destroyed when combined with acidic substances. According to tests, if vinegar is added at the same time when cooking, the consumption rate of iodine will be reduced by 40 to 60%. In addition, when iodized salt meets acidic vegetables (such as sauerkraut), the consumption rate will also decrease.

Notes

Excessive salt consumption can cause cataracts·

Australian researchers have found that if the salt content in food is too high, the possibility of cataracts will increase. Increase.

Cataracts are whitening of the lens of the eye and can lead to blindness if left untreated.

A study by Dr. Robert G. Cumming of the University of Sydney and colleagues found that people with the highest sodium intake were twice as likely to develop posterior subcapsular cataracts as those with the lowest sodium intake. Cataract is the most damaging form of vision. Their research report was published in a recent issue of the journal American Epidemiology.

The researchers examined the eyes of about 3,000 adults aged 49 to 97 and asked the subjects to fill out a questionnaire about their eating frequency. 160 people had posterior subcapsular cataracts, and 970 had one of two other cataracts not related to sodium intake.

The study also found that people with high salt intake may also suffer from other diseases that can lead to cataracts, such as diabetes or high blood pressure, and may have taken corticosteroid anti-inflammatory drugs. [2]

The pros and cons of salt on humans

Usually, the salt concentration of water in human tissue is 0.9, that is, 100 ml of water contains 0.9 grams of salt.

Salt is not only an indispensable condiment in people's meals, but also an indispensable material component in the human body. Its main ingredient is sodium chloride, which is a neutral inorganic salt with a mild taste. It tastes salty and is cold in nature. It enters the stomach, kidneys and large and small intestine meridians. It has the functions of clearing away heat and detoxifying, cooling blood and moisturizing dryness, nourishing the kidneys and laxative, killing insects and reducing inflammation, inducing vomiting and stopping diarrhea.

"Shen Nong's Materia Medica" records: "Salt is suitable for athlete's foot, cleans teeth, strengthens teeth, and treats all skin diseases." Washing feet with salt and perilla root decoction in water can cure beriberi. Scrubbing the skin with salt water can make the skin healthy and enhance its resistance. Salt has an analgesic effect. If hot water burns the skin, rubbing some salt (or soy sauce) can reduce the pain. Drinking some light salt water in hot weather can prevent and treat constipation, sore throat, toothache and abdominal pain. Drinking a glass of salted water every morning can prevent hoarseness in the voice. If you accidentally eat poisonous food, drink some salt water to detoxify. Milk is prone to spoilage in summer and autumn, so adding less salt to the milk can extend the shelf life of the milk. Before eating vegetables and fruits, soak them in light salt water for 20 minutes. This can remove residual pesticides and parasite eggs and kill germs. Wash the fish in salt water before frying it so that the fish will have no earthy or fishy smell. In addition, table salt can soften acidic bumps in the body.

From a physiological perspective, salt is of great significance to maintaining human health: Salt can help the human body digest food. The salty taste of salt can stimulate people's sense of taste and increase oral saliva secretion, thus increasing appetite and improving food digestibility. Salt can participate in body fluid metabolism. Salt is an important component of body fluids. People who work at high temperatures sweat excessively and need to supplement with food and beverages; people with excessive vomiting and diarrhea need to inject physiological saline; people with massive blood loss also need to drink warm salt water urgently. These are all because Salt can maintain the body's osmotic pressure and acid-base balance.

In the past, we foolishly believed that salt was a necessary food for human survival. Modern science has given us a loud slap in the face. Salt is one of the killers of human health. Excessive consumption of salt can cause humans to suffer from many diseases. People in China generally consume too much salt. According to the national nutrition survey, the amount of salt used ranges from 12 grams to 15 grams from the south to the north. According to the 6 grams prescribed by the World Health Organization, ours is more than double. Moreover, eating too much salt will have a direct impact on the body, so we must control the amount of salt we eat, mainly light, and eat scientifically.

1. Excessive salt consumption can cause high blood pressure

According to expert surveys, there is a certain relationship between the amount of salt eaten and the incidence of hypertension. The more salt eaten, the higher the incidence of hypertension. The Eskimos in Alaska eat very little salt and basically do not suffer from high blood pressure. However, the residents of northern Japan, who eat about 20 grams of salt a day, have an alarmingly high incidence of hypertension. In my country's Guangdong Province, where salt consumption is low, the incidence of hypertension is only 3.5. However, for northerners who like salty food, the incidence of hypertension is significantly higher. This is because salt, under the action of certain endocrine hormones, can increase the sensitivity of blood vessels to various blood pressure-raising substances, causing spasm of small arteries, raising blood pressure, and may also accelerate the hardening process of small renal arteries. At the same time, salt also has the function of absorbing water.

If there is too much salt accumulation, the water content will be greatly increased, and the blood volume will also increase accordingly. In addition, the potassium and sodium ratio inside and outside the cells will be imbalanced, which will damage the function of red blood cells, make the blood flow viscous and slow, and aggravate the problems of blood circulation. Work burden leads to further increase in blood pressure.

2． Too much salt can cause edema

Because too much salt causes sodium to accumulate in the body, and sodium is hydrophilic, it causes edema and increases the burden on the kidneys.

3． Excessive salt intake can cause colds

High concentrations of sodium salt have a strong osmotic effect and will affect the disease resistance of human cells. Excessive salt consumption will, firstly, reduce saliva secretion, resulting in a corresponding decrease in lysozyme in the oral cavity, giving the virus a chance to implant in the oral cavity. Second, due to the penetration of sodium salt, the defense function of epithelial cells is inhibited and the disease resistance is greatly lost. Cold viruses can easily invade the human body through cells that have lost their barrier function, so it is easy for people to catch colds. Upper respiratory tract inflammation such as pharyngitis and tonsillitis also often occur. Excessive salt consumption can cause heart disease.

4. Too much salt can harm the heart

The "Nei Jing" has this record: "Eating too much salt will cause the pulse to condense and change color." "If the taste is too salty, the bones will be damaged and the heart will be suppressed." Too much salty food makes people sad. Eating too much salty food can constrict the arterioles, which is harmful to the heart. For example, the death rate from heart disease among residents in Hunan is four percentage points higher than the national average. This is closely related to the heavy reliance on pork and excessive salt consumption.

5. Excessive salt consumption can cause gastric cancer

The largest number of gastric cancer patients in Japan are in Akita and Yamagata prefectures in the northeast, where salty foods are popular. There are also many people suffering from gastric cancer. Akita Prefecture, which ranks first in the number of gastric cancer cases, launched a salt reduction campaign, resulting in a reduction of more than 20% in deaths from gastric cancer. It can be seen that excessive salt consumption is a major cause of cancer. There are no carcinogens in salt, but it can easily damage the gastric mucosa and help carcinogens. In addition, kidney disease and stroke are also closely related to excessive salt consumption.

Therefore, a reasonable diet of salt should be 2-5 grams per day. Don’t eat too salty vegetables in your daily life, especially for the elderly and infants. Food cannot be given to children according to the taste of adults, which will harm the children and induce high blood pressure and myocardial weakness. When cooking for the elderly, try to use spicy seasonings such as vinegar, shepherd's purse, and pepper to replace salt and reduce the amount of salt.