Encyclopedia of Family Medicine

Chapter 5 Human Body and Nutrition (5)
Fat in cooking oil plays an important role in human health.In the cold winter, the body needs to produce more heat to keep warm. People who work in the field or heavy manual workers consume more calories, so they should eat more fat.In the hot summer, people's appetite is often poor. In addition, due to sweating and drinking a lot of water, the gastric juice is diluted and the digestive function is reduced, so you should eat less oil.In addition, people suffering from liver and gallbladder diseases have reduced bile secretion and fat is not easy to digest, so they should not eat more oil; people suffering from dysentery, acute gastroenteritis, and diarrhea should not eat greasy food due to gastrointestinal dysfunction. One of the factors that cause the body to gain weight. After middle age, if the amount of activity is small, do not pay attention to exercise, eat food with too much oil, and accumulate a lot of fat under the skin and viscera, such as the heart, liver, kidney and other organs, it will accelerate Premature aging and disease of organs can harden blood vessels and cause diseases such as high blood pressure and coronary heart disease.

As for infants and adolescents, they are in the stage of growth and development, they have a lot of activities and consume a lot of heat energy. Eating more oil is beneficial to human health.

The Importance of Cholesterol

Cholesterol is widely distributed in the whole body of the human body. It is not only one of the lipids in the blood, but also the basic component of cell biomembranes.

In the human body, the highest cholesterol content is the adrenal gland and the brain.It can turn into hormones, and without cholesterol, the synthesis of sex hormones, adrenal cortex hormones becomes a problem.The ultraviolet rays in the sun directly irradiate the human skin, which can be produced into vitamin D3. This kind of vitamin D7 is free and self-made in the body, and its raw material is [-]-dehydrocholesterol.Bile is one of the important digestive juices for digesting and absorbing fat. The main component of bile is bile acid, and the main component of bile acid is cholesterol.Recent studies have found that natural cholesterol has anti-cancer properties.It can be seen how important cholesterol is to life.

A small part of human cholesterol comes from food, and most of it is synthesized by the body itself.Under normal circumstances, the amount of synthesis in the body can be automatically adjusted to maintain a certain level. Too much or too little is not good for health.For teenagers with strong metabolism and young adults who often participate in physical activities or insist on exercising, harmful cholesterol is not easy to accumulate, and there is no need to excessively restrict cholesterol intake.However, for middle-aged and elderly people, due to changes in endocrine levels, or due to excessive mental stress, reduced physical activity, or suffering from hypertension, obesity and other diseases, lipid metabolism disorders, resulting in increased serum cholesterol, not only excessive intake of saturated fat and Cholesterol can cause this disorder, which in turn can promote elevated blood lipids or develop as a consequence of atherosclerosis.

The role of carbohydrates in the human body

Carbohydrates, also known as sugars, are the main source of energy for the human body.After it is digested in the human body, it is mainly absorbed and utilized in the form of glucose.Glucose is rapidly oxidized and provides (releases) energy.Each gram of carbohydrates can release 4 kilocalories of heat energy when oxidized and burned in the human body.Starch food is the staple food in my country, and 60-70% of the total heat energy in the human body comes from sugar in food, which is mainly supplied by food containing starch such as rice, flour, corn, and millet.These carbohydrates are the building blocks of the body and play important roles in a variety of life processes.For example, glycolipids formed from carbohydrates and lipids are components of cell membranes and nerve tissues; mucins synthesized from mucopolysaccharides and proteins are the basis of connective tissue; carbohydrates and proteins are combined into glycoproteins to form antibodies, certain enzymes and Hormones and other substances with important biological activities.The human brain and red blood cells must rely on blood sugar for energy, so sugar is also needed to maintain the normal function of the nervous system and red blood cells.Carbohydrates are also closely related to fat and protein metabolism.Carbohydrates have the effect of saving protein.When protein enters the body, the concentration of free amino acids in the tissues increases, and the synthesis of the amino acids into protein in the body is an energy-consuming process. If carbohydrates are taken at the same time to supplement energy, part of the amino acids can be saved, which is beneficial to protein synthesis.Dietary fiber is a sugar that cannot be broken down by human digestive enzymes.Although it cannot be absorbed, it can absorb water, making the stool soft and bulky, thereby promoting intestinal peristalsis and helping defecation.

The function of carbohydrates in the human body
(1) Supply energy (heat).Supplying energy is the main function of sugar, and it is also the main component of nerves and cells.The average adult needs 6 grams of sugar per kilogram of body weight per day.Although fat produces twice as many calories per unit as sugar, the diet contains more sugar than fat.Sugar is the thermogenic nutrient that keeps the body warm.People often say that "when you are full, you will be warm". This is the truth.

(2) Form body tissue.Sugar participates in many life activities in the body.For example, glycoprotein is an important component of cell membrane; mucin is an important component of connective tissue; glycolipid is an important component of nerve tissue.

(3) Protect liver and detoxify.When the liver glycogen reserves are abundant, the body's resistance to certain bacterial toxins will increase accordingly.Therefore, keeping the liver rich in glycogen can protect the liver and improve the normal detoxification function of the liver.

(4) Save protein.Sugar is widely distributed in nature with easy sources.Using sugar to supply heat can save protein, and make protein mainly used for tissue construction and regeneration.

(5) Anti-ketone effect.Fat is completely oxidized in the human body and needs sugar for energy.When there is insufficient sugar in the body, or the body cannot use sugar (such as diabetics), most of the energy required is supplied by fat.Incomplete fat oxidation will produce a certain amount of ketone bodies, and its excessive accumulation will make the acidity in the blood higher and the alkalinity lower, which will cause ketone coma.So sugar has an anti-ketogenic effect.

(6) Enhance intestinal function and synthesize vitamins.The cellulose in sugar that is not digested and absorbed by the body can promote intestinal peristalsis, prevent constipation, provide energy for microorganisms in the intestinal cavity, and synthesize vitamin B.

(7) Increase appetite.Sugar is not only food, but also can be used as seasoning to adjust food flavor and increase appetite.

The dangers of eating too much sugar
In the preparation of food, sugar can add sweetness, flavor and interest, and is an easily digestible source of heat energy, so some people especially like sweets.But sugar and sweets should not be eaten too much, because eating too much is not only useless, but harmful.

(1) Insufficient sugar and nutrition.If you eat more sugar or sweets every day, then eat less other nutrient-rich foods.Especially for children, if they eat too much sugar or sweets, they will reduce their meal intake, so protein, minerals, vitamins, etc. will not be replenished in time, resulting in nutritional deficiencies.

(2) Sugar and dental caries.Eating sweets often provides good conditions for the growth and reproduction of bacteria in the oral cavity. It is easy to be affected by lactic acid bacteria to produce acid, decalcify the teeth, and easily cause dental caries.

(3) Sugar and obesity.If you eat too much sugar, the remaining part will be converted into fat, which can bring about the consequences of obesity, and can lead to obesity, diabetes and hyperlipidemia.

(4) Sugar and fractures.Too much sugar reduces the amount of vitamin B in the body.Because vitamin B is an essential substance when sugar is converted into energy in the body, insufficient vitamin B1 greatly reduces the activity of nerves and muscles.Therefore, accidental falls are prone to fractures.

(5) SUGAR AND CANCER.Experimental studies have confirmed that cancer is closely related to calcium deficiency, and white sugar, which can cause calcium deficiency, is considered to be one of the inducing factors causing certain cancers.

(6) SUGAR AND LIFE.People who eat high-sugar food for a long time can cause malnutrition, enlargement of liver and kidney, and increase in fat content, and their average life expectancy will be shortened.

Cultivate correct sugar eating habits

First talk about how to establish the habit of eating sugar correctly.People who eat sugar, especially children who love to eat sugar, should correct their habit of eating sugar. When eating sugar, chew the sugar into pieces to shorten the time that the sugar stays in the mouth as much as possible. They should not eat sugar before going to bed. The secretion of saliva stops, and if there is no saliva to clean the mouth, the fermentation of sugar will produce more acid, which is not conducive to the health of teeth; after eating sugar, it is best to rinse your mouth with plain water to minimize the sugar content in your mouth.

Regarding the reasonable consumption of sugar, due to the difference in people's living habits, dietary structure and labor intensity, nutrition scholars at home and abroad have great differences in formulating standards.my country's current supply of sugar accounts for about 60-70% of the total energy demand.That is: about 4-6 grams per kilogram of body weight per day for adults, about 6-10 grams per kilogram of body weight per day for children and adolescents, and about 1 grams per kilogram of body weight for infants under 12 year old.In foreign countries, the more consistent opinion in recent years is that the daily body weight should be controlled at about 0.5 grams per kilogram.That is to say, children with a weight of 20 kg have a daily sugar intake of 10 grams, and adults with a body weight of 60 kg have a daily sugar intake of about 30 grams.Infants and young children who mainly eat cow and goat milk should also pay attention to adding less sugar and cultivate eating habits that are not addicted to sweets.

Strictly controlling sugar intake will not affect the body's demand for sugar, because in addition to carbohydrate foods, there are too many sugary processed foods.When you drink a cup of coffee or black tea, you have taken in 10-15 grams of sugar, eat a piece of dessert, and get another 20 grams of sugar, and then drink a bottle of cool drink, and get another 30 grams of sugar.These are enough for the body's daily demand for sugar.

Nutritional value of sucrose

In daily life, the white sugar, granulated sugar, and brown sugar we commonly use are all sucrose, which is made from sugar cane or sweet radish (that is, beet stems).After making sugar, it becomes white sugar after some processing and refining.Granulated sugar and soft white sugar are only different in crystal size. The crystal particles of granulated sugar are large and contain little water, while the crystal particles of soft white sugar are small and contain more water.They are all pure carbohydrates, which only provide heat energy and do not contain other nutrients, but they have the effects of nourishing the lungs and promoting body fluid, harmonizing the lungs, and soothing the liver qi.Brown sugar is not highly refined sucrose. In addition to having the function of carbohydrates to provide heat, it also contains trace elements such as iron, chromium and other minerals.Although its appearance is not good, its nutritional value is much higher than that of white sugar and granulated sugar. It contains 90 mg of calcium and 4 mg of iron per 3 grams, which are [-] times that of white sugar and granulated sugar.

Traditional Chinese medicine believes that brown sugar is warm in nature and sweet in taste, and enters the spleen. It has the functions of nourishing qi, slowing the middle, and transforming food.The national habit of our country advocates that women eat some brown sugar after giving birth, thinking that it has the effect of nourishing blood and promoting blood circulation.When suffering from cold and abdominal pain, brown sugar ginger soup is often used to dispel the cold.

vitamins that regulate metabolism
Vitamins are organic compounds that are essential for human metabolism.Many vitamins are known to be coenzymes of enzymes or constituent molecules of coenzymes.Therefore, it can be considered that vitamins exist in human tissues in the form of "biologically active substances".Most vitamins cannot be synthesized in the human body, or the amount of synthesis is insufficient to meet the needs of the human body.Therefore, it must be ingested from food.The content of vitamins in food is less, and the human body's requirement is not much, but it is an absolutely indispensable substance.If there is a lack of vitamins in the diet, it will cause metabolic disorders in the human body, resulting in vitamin deficiency.For example, lack of vitamin A can cause night blindness, dry eyes and dry skin; lack of vitamin D can cause rickets; lack of B1 can cause beriberi; lack of B2 can cause cheilitis, angular stomatitis, glossitis and scrotum; lack of PP can cause pellagra Disease; lack of B12 can suffer from pernicious anemia, lack of C can suffer from scurvy.

The human body is like an extremely complex chemical factory, constantly carrying out various biochemical reactions.Its reaction is closely related to the catalysis of enzymes.For enzymes to be active, coenzymes must participate, and some vitamins themselves are coenzymes or part of coenzymes.Therefore, vitamins are important substances for maintaining and regulating the normal metabolism of the body.

Vitamins are a huge family. There are dozens of vitamins known so far, which can be roughly divided into two categories: fat-soluble and water-soluble.The former includes vitamins A, D, E, and K, and the latter category includes the B vitamins and vitamin C, as well as many "vitamins."

daily intake of vitamins

Vitamins are organic compounds needed for human nutrition and growth.If the body lacks vitamins, certain diseases will appear.Therefore, some people think that vitamins are nutrients, and intake is "the more the better".Do people need more vitamins?the answer is negative.The key to reasonable nutrition is "moderation".Excessive intake of certain vitamins is not only useless but harmful to the body.

We know that vitamins can be roughly divided into two categories: water-soluble (vitamins B, C) and fat-soluble (vitamins A, D, K, etc.).The excess of water-soluble vitamins can generally be excreted with urine, and the excess of fat-soluble vitamins A or D cannot be excreted.This will give people the impression that eating too much water-soluble vitamins is harmless. Some people advocate taking 3-5 grams of vitamin C per day to achieve the purpose of health care.In fact, this is harmful. Experiments have confirmed that long-term oral administration of more than 1 gram of vitamin C can cause oxaluria, hyperuricemia, and hypercalcemia.Some people may have rashes, edema, drop in blood pressure, and nausea all over the body.Among the fat-soluble vitamins, poisoning caused by excessive intake of vitamin A and vitamin D is the most common.Excess vitamin A can cause insomnia, asthma, dizziness, hair loss, nausea, and diarrhea. Excess vitamin D can cause loss of appetite, fatigue, constipation, weight loss, and low-grade fever.

Normal people need 50-100 mg of vitamin C, 2500-3000 IU of vitamin A and 300-400 IU of vitamin D every day.

The role of various vitamins
(1) Vitamin A.Maintain normal vision, prevent night blindness; maintain epithelial cell tissue health, promote growth and development; increase resistance to infectious diseases, prevent and treat dry eye disease.

(2) Vitamin D.Regulate the metabolism of calcium and phosphorus in the human body, promote the absorption and utilization of calcium and phosphorus, and promote bone growth.

(3) Vitamin E.Maintain normal reproductive ability and normal muscle metabolism; maintain the integrity of the central nervous system and vascular system.

(4) Vitamin K.stop bleeding.It is not only the main component of prothrombin, but also promotes the production of prothrombin in the liver.

(5) Vitamin B1.Maintain the normal functions of circulation, digestion, nerves and muscles, adjust the functions of the gastrointestinal tract, form decarboxylase enzymes, participate in the metabolism of sugar, and prevent beriberi.

(6) Vitamin B2.Also known as riboflavin.Riboflavin is a component of many important coenzymes in the body. These enzymes can transfer hydrogen in the process of substance metabolism in the body. It is also a necessary substance for protein, sugar, fatty acid metabolism and energy utilization and composition.Can promote growth and development, protect the health of eyes and skin.

(7) Vitamin PP (niacin).It plays the role of transferring hydrogen during the physiological oxidation process of cells, and has the effect of preventing and treating pellagra.

(8) Vitamin B6.It plays an important role in protein metabolism and treats neurasthenia, dizziness, atherosclerosis, etc.

(9) Pantothenic acid (vitamin B5).Anti-stress, anti-cold, anti-infection, prevent the toxicity of certain antibiotics, and eliminate postoperative abdominal distension.

(10) Folic acid (vitamin M).Anti-anemia; maintain the normal growth of cells and the function of the immune system.

(End of this chapter)