The effect of iron on human body is manifested in many aspects. Iron participates in the transport and storage of oxygen. Hemoglobin in red blood cells is the carrier for transporting oxygen; Iron is a component of hemoglobin, which combines with oxygen and is transported to all parts of the body for people to breathe and oxidize, thus providing energy (energy food), digesting food and obtaining nutrition; Myoglobin in human body exists in muscle and contains heme, which combines with oxygen and is the "oxygen bank" in muscle. During exercise (sports food), the oxygen in myoglobin is released to supply the oxygen needed for muscle activity at any time. Heart, liver and kidney have high physiological activity and biochemical function, and there is a lot of iron stored in mitochondria. Mitochondria are "energy factories" of cells, and iron is directly involved in the release of energy.
Iron can also promote development; Enhance resistance to diseases; Regulate tissue respiration to prevent fatigue; Constitute heme to prevent and treat iron deficiency anemia; Restore good skin color. The total amount of iron in adults is about 4 ~ 5g, of which hemoglobin accounts for 72%, myoglobin accounts for 3% and other compounds account for 0.2%. The rest is reserved iron, which is stored in the reticuloendothelial system of liver, spleen and bone marrow in the form of ferritin, accounting for about 25% of the total iron.
The iron in food is mainly Fe(OH)? The complex exists in the form of ferrous ion, which is reduced to ferrous ion under the action of gastric acid, and then forms a complex with vitamin C, some sugars and amino acids in intestinal contents, which is absorbed in duodenum and jejunum.
Iron can be reused by the body in metabolism. Generally speaking, there are almost no other ways of loss except intestinal secretions and epithelial shedding of skin, digestive tract and urethra.
Phosphate, carbonate, phytic acid, oxalic acid, tannic acid, etc. Existing in the diet can form insoluble iron salts with non-heme iron, preventing the absorption of iron. Decreased gastric acid secretion will also affect iron absorption.
The balance of iron refers to a stable state, that is, the iron absorbed from diet may not only supplement the iron actually lost by the body, but also meet the needs of body growth (and pregnancy). The balance of iron depends on the coordination of iron absorption, iron transport and iron storage.
The body has three unique mechanisms to maintain iron balance and prevent iron deficiency and excessive accumulation in the body.
(1) Reuse of iron in erythrocyte catabolism. The biological half-life of iron in the body is 5.9 years for adult males and 3.8 years for adult females (premenopausal).
⑵ According to the nutritional status of iron in the body, adjust the absorption of iron in the intestine.
⑶ Add a unique storage protein-ferritin, which can be stored or released to meet the needs of extra iron, such as 1/3 after pregnancy.
The homeostasis mechanism in organisms coordinates the demand, utilization and storage of iron in many aspects to maintain this balance. Half of the basic iron loss in the body is the loss of exfoliated cells and blood in the gastrointestinal tract, and the level of hemoglobin can affect this basic loss to some extent. Similarly, hemoglobin level will also affect the amount of iron loss during menstruation. When the decrease of hemoglobin develops into iron deficiency anemia, it can effectively reduce the loss of basic body and menstrual iron. When the body is severely anemic or has too much iron, it will also reduce or increase the loss of iron in the skin. The absorption of iron by intestine mainly depends on the nutritional status of iron in the body and the characteristics of diet (iron content, form and bioavailability). From the regulatory mechanism, in most cells in vivo, iron transport and storage are regulated by iron regulatory protein (1RP8), transferrin receptor and iron reaction element IREs in ferritin H and I-chain mRNA-3' or 5'UTR at the post-transcriptional level. Erythrocyte iron requirement is high, and its regulation is also at transcription level, which can take precedence over post-transcriptional regulation of other cells. The world health organization recommends that the amount of iron (iron-containing food) for adult men is 5 ~ 9 mg; Adult female 14 ~ 28 mg. The Nutrition Society of China recommends that infants to 9-year-old children need iron 10 mg per day, 10 to 12-year-old children (children's food) 12 mg, 13 to 18-year-old young men (men's food)/kloc. 28 mg for lactating mothers and pregnant women (pregnant food).
Recommended daily intake:
Adult intake is10 ~15mg; Pregnant women need 30mg.
1 month, the iron loss of women is about twice that of men (male food); Copper, cobalt, manganese and vitamin C are necessary to absorb iron.
Replenishment cycle: daily replenishment is recommended. The daily intake of ordinary people aged 0 ~ 0.5 years is 0.3mg. The daily intake of pregnant women is early 15mg, late 25mg and lactation stage 25mg0.5 0.5 ~ 1 year 10mg 1 4 years 12mg4 ~ 7 years/kloc. Female 18mg 14 years old ~ 18 years old male 20mg female 25mg 18 ~ 50 years old male15mg; Female 20mg50 years old 15mg 1, iron is an important part of hemoglobin, and the function of hemoglobin is to transport oxygen to cells and take carbon dioxide out of cells. The link structure of heme and tetraglobulin in hemoglobin provides an effective mechanism, that is, it can combine with oxygen without being oxidized, and plays a key role in the transport of oxygen from lung to tissue.
2. Myoglobin is composed of heme and globulin chains, and exists only in muscle tissue. Its basic function is to transport and store oxygen in muscles.
3. Cytochrome is a series of heme compounds. Through its electron conduction in mitochondria, it has a very important influence on respiration and energy metabolism. For example, cells A, B and C are necessary to generate energy through oxidative phosphorylation.
4. Iron in other iron-containing enzymes can be non-heme iron, NAP dehydrogenase and amber dehydrogenase, which participate in energy metabolism, as well as heme-iron-containing catalase, poly-oxidase (involved in trihydroxy acid cycle), phosphoenolpyruvate kinase (rate-limiting enzyme in sugar production pathway) and nucleotide reductase (enzyme needed for DNA synthesis).
5. Iron catalyzes the transformation of β -carotene into vitamin A, the synthesis of purine and collagen, the production of antibodies, the transport of lipids in blood and the detoxification of drugs in liver. Iron is also closely related to immunity. Studies have shown that iron can improve the body's immunity, increase the phagocytic function of neutrophils and phagocytes, and enhance the body's anti-infection ability. Colla Corii Asini is a traditional blood-enriching formula in China, and ferrous lactate is a good bivalent iron-supplementing preparation. Many blood-enriching products on the market are used as a formula alone.
Iron is the key for heme to carry oxygen.
The human body will be short of iron because of unbalanced nutrition, trauma, female physiological cycle and other reasons. According to statistics, the iron deficiency rate of women in China is over 60%, and that of vegetarian women is over 70%.
Because of the monthly physiological cycle, women lose a lot of blood iron, so their demand for iron is much higher than that of men. Because people in China use far less red meat than westerners, they get less iron from natural food.
Iron mostly exists in the liver, spleen, bone marrow and red blood cells of human body. Because its main function is to carry oxygen, the demand for iron in infants and pregnant women will be particularly high, and insufficient iron intake in children and young children may also affect brain development. Therefore, pregnant women, children and nursing mothers should pay special attention to iron intake. 1. Anemia: In severe cases, it can increase the mortality rate of children and mothers and obviously reduce the working ability of the body.
2. Behavior and intelligence: Iron deficiency can cause damage to psychological activities and intellectual development and behavior changes. Iron deficiency (lack before anemia) will also damage children's cognitive ability, and it is difficult to recover after iron supplementation in the future. Animal experiments show that short-term deficiency can reduce the iron content in the brain of young animals. In the future, iron supplementation can correct iron storage in the body, but it has no effect on iron in the brain. Long-term iron deficiency will obviously affect physical endurance. The animal experiments carried out by Finch et al. show that the damage of iron deficiency to the running ability of animals has nothing to do with the level of hemoglobin, but is caused by the damage of muscle oxidative metabolism caused by iron deficiency.
In terms of immunity and anti-infection ability, both human and animal experiments have recorded that one of the characteristics of iron deficiency is the decline of anti-infection ability.
1. In terms of body temperature regulation, another feature of iron deficiency anemia is that the ability to maintain body temperature in a cold environment is impaired.
2. In the aspect of lead poisoning, animal and human experiments have proved that iron deficiency will increase the absorption of lead.
3, some pregnancy consequences, sweaty bowel disease research shows that anemia in early pregnancy is related to premature delivery, low birth weight infants and fetal death.
4. Symptoms of iron deficiency include pale skin, tongue pain, fatigue or weakness, loss of appetite and nausea.
Effect of iron deficiency on immune system;
1. The ability to resist the invasion of pathogenic microorganisms is weakened.
2. Reduce the reaction speed of immune cells from rest to war.
3. Reduce the activity of antioxidant biochemical enzymes.
4. Antibody production stops or proceeds at a very slow speed.
5. Iron deficiency anemia, insufficient oxygen supply to cells. The result is listless, tired and tired all day, and more susceptible to infection.
Excessive free iron flowing in the blood will not only help to resist and protect the human body, but will be swallowed up by bacteria and become food for bacteria, which will multiply in large numbers. This is why we must be more careful when we supplement iron for our children.
Housewife syndrome: Some people abroad have done a survey and found that 40%-60% of women of childbearing age aged 25-50 may have symptoms such as general weakness, listlessness, poor sleep at night when they don't want to get up in the morning, mood swings, depression, unhappiness, etc., and often can't help crying suddenly, memory loss, inattention, etc. The reason is iron deficiency, but there is often no obvious anemia, just low serum iron. Because it mostly happens to housewives, it is called "housewife syndrome". After iron supplementation, the above symptoms can be significantly improved.
Female coldness: The body temperature of iron-deficient women is higher than that of normal women 13%, and the sclera is blue. Because iron is an important auxiliary factor of collagen synthesis, when the body lacks iron, the synthesis of collagen is blocked, which makes the sclera composed of collagen fibers very fragile and the pigment film below it will appear blue. So the white eyeball we see is blue, which is also a sign of iron deficiency.
Pica: Iron deficiency can also cause pica, that is, people are not interested in normal diet, but have a hobby for chalk, paste, mud, lime, cloth, paper, candles and other foreign bodies, and eat with relish. It is found that pica patients are obviously deficient in iron and zinc, and can get better quickly after iron and zinc supplementation. There are many forms of pica caused by iron deficiency. The most common thing is to eat ice, and I like to eat ice in cold weather.
Others: Some studies have found that infants often don't laugh, feel depressed, unsociable, inactive, cry, and their IQ is significantly lower than that of normal children.
Iron deficiency anemia is not only manifested as anemia (hemoglobin is lower than normal), but also belongs to systemic malnutrition. Because the degree of iron deficiency in the body and the development of the disease are different, the clinical manifestations of anemia are also different. At first, the patient had no obvious symptoms, but the hemoglobin was lower than normal at the time of blood test. With the further development of the disease, there are different degrees of hypoxia symptoms. Patients with mild anemia often feel dizzy and tinnitus, inattention and memory loss. The easiest thing to find is the pale complexion, eyelids and nails caused by iron deficiency anemia in skin and mucosa, and the slow growth of children's height and weight. The further development of the disease will also lead to rapid heartbeat and frequent conscious palpitations. Muscle hypoxia is often manifested as general weakness and fatigue. Hypoxia of digestive tract can lead to loss of appetite, abdominal distension and diarrhea, and even nausea and vomiting. In severe anemia, there may be manifestations of anemia heart disease such as enlargement of heart, abnormal electrocardiogram and even heart failure, and some of them may be insane or unconscious. In addition, about 15% ~ 30% of the cases showed neuralgia and paresthesia; Children may have partial eclipse and pica (like to eat clods, cinders, etc. ), slow response, mental retardation, academic performance, irritability and susceptibility to infection. Infants with iron deficiency anemia may have intestinal bleeding. In recent years, medical research has found that senile deafness is related to iron deficiency.
The chronic chlorosis of adolescent women (female food) is mainly caused by iron deficiency in the body, which is manifested as small cell hypopigmentation anemia and iron deficiency anemia. The main reasons for girls or adolescent women suffering from this disease are the increase of iron needed by the body, the loss of too much iron during menstrual cramps or the lack of stomach acid, which leads to insufficient iron intake.
Because of iron deficiency, the activity of iron-containing enzymes in the body decreases, causing metabolic disorders in many tissues and cells. Clinical symptoms and the degree of anemia are related to the severity of the disease. Mild patients may have no conscious discomfort except sallow complexion. Patients with severe anemia may also have glossitis, atrophy of tongue mucosa, slippery tongue, congestion and burning sensation. Sometimes there will be symptoms such as esophageal foreign body sensation, suffocation or dysphagia.
Iron deficiency can also cause dysphagia syndrome, and its clinical manifestations are hypochromic anemia, dysphagia, angular stomatitis, abnormal tongue sensation, spoon nails and so on. Women account for about 90% of this disease, and children are rare. In patients with dysphagia, no abnormality can be found by esophagoscopy or X-ray examination, and esophageal mucosa is occasionally formed.
The increase of iron entering the body through various ways will lead to excessive iron storage in the human body, which will lead to the potential harmful effects of iron in the body. Excessive storage of iron in the body is related to many diseases, such as heart and liver diseases, diabetes and some tumors.
Liver is the main part of iron storage, and iron excess often involves the liver and becomes the main target organ of iron excess injury. Liver iron overload leads to: 1, liver fibrosis and even cirrhosis; 2. Hepatocellular tumor.
There have been many reports about the relationship between iron excess and heart disease. Many authors believe that iron participates in the formation of atherosclerosis by catalyzing the generation of free radicals, promoting the peroxidation of lipoprotein and protein, and forming oxidized LDL.
The lipid peroxidation caused by excessive iron is enhanced, which leads to the imbalance of oxidation and antioxidant system, directly damages DNA and induces mutation, which is related to tumors of liver, colon, rectum, lung, esophagus, bladder and other organs. Although iron (iron food) is an essential trace element (trace element food) for human body, iron itself is not toxic, but excessive intake or accidental intake of iron preparations may also lead to iron poisoning.
Acute iron poisoning mostly occurs in children. When children take too much syrup coated with colored sugar-coated tablets made of solid iron or liquid iron, acute poisoning symptoms may occur about 1 hour, which are manifested as epigastric discomfort, abdominal pain, nausea and vomiting, diarrhea and black stool, even purple face, lethargy or irritability, acute intestinal necrosis or perforation, and even shock death. It can be seen that parents need to be reminded that when adding iron and iron preparations to children (children's food), the dosage must be strictly controlled according to the doctor's advice, and it must not be taken indiscriminately to prevent poisoning.
Chronic iron poisoning mostly occurs in middle-aged and elderly people over 45 years old (elderly food), and most of them are men (male food). Because of taking iron preparations for a long time or taking too much iron from food, the iron content in the body is more than 10 ~ 20 times of the normal level, and chronic poisoning symptoms may occur: there are a lot of iron deposits in the liver and spleen, which can be manifested as cirrhosis, osteoporosis, cartilage calcification, brown or dark skin, and decreased insulin secretion, leading to diabetes (diabetic food). It will also affect the development of adolescent reproductive organs (juvenile food). It is reported that iron poisoning can also induce epilepsy.
For the treatment of iron poisoning, doctors should deal with it according to the symptoms, and patients should be treated according to the doctor's advice. To prevent iron poisoning, first, when taking ferrous sulfate and other iron agents to treat anemia, it is necessary to prevent overdose and prevent children from taking it by mistake. It is best to take iron porphyrin supplement, a new product of modern science and technology, which not only has high absorption rate, but also is not easy to produce side effects; Second, acidic foods should not be stored in iron containers for a long time, and acidic foods such as hawthorn should not be cooked in iron pots to avoid a large amount of iron dissolving into food under acidic conditions. Infants and young children should add complementary food in time; Add egg yolk, fish sauce, poultry blood, etc. 4 ~ 5 months; Add liver mud, minced meat, blood, jujube paste and other foods. Starting from 7 months; In addition, from 2 months for premature infants and 4 months for full-term infants, iron can be supplemented under the guidance of doctors to strengthen prevention.
Avoid iron loss in daily life;
Avoid drinking too much tea and coffee: because tannic acid in tea and polyphenols in coffee can form insoluble salts with iron and inhibit the absorption of iron. Therefore, women should drink enough coffee and tea, 1 ~ 2 cups a day is enough.
Cooking in an iron pan absorbs iron easily. Use less aluminum pot, because aluminum will prevent the absorption of iron;
Adhere to the principle of safety and effectiveness, and take iron supplements in time;
The common oral iron supplements in the market are mostly ferrous fumarate, ferrous sulfate and ferrous lactate. However, the first two drugs stimulate the stomach much more than ferrous lactate. Ferrous fumarate and ferrous sulfate are not recommended for patients with gastrointestinal diseases.
After choosing a good iron supplement preparation, you should also pay attention to the following issues when taking it:
Take iron supplements after meals.
Avoid taking both milk and iron.
Eat more vegetables and fruits: Vegetables and fruits are rich in vitamin C, citric acid and malic acid. These organic acids can form complexes with iron, thus increasing the solubility of iron in the intestine and promoting its absorption.
Eat more foods rich in iron;
Such as: egg yolk, kelp, seaweed, fungus, pig liver, longan, pig blood and so on.
The latest research found that even in women with normal hemoglobin, iron has anti-fatigue effect. After dietary iron supplementation, their physical strength, mood and attention have improved.
Iron fortified soy sauce
China is one of the countries with serious iron deficiency and iron deficiency anemia. The report of the fourth national survey on nutrition and health status of residents shows that the average anemia rate of residents in China is 20. 1%, and the anemia rates of children under 2 years old, elderly people over 60 years old and women of childbearing age are 3 1. 1%, 29. 1% and 65438 respectively.
Many people question the safety of iron fortified soy sauce. Chen Junshi explained that iron fortified soy sauce can be safely eaten for a long time. The recommended intake of iron in Dietary Guidelines for China Residents issued by China Nutrition Society is not less than 15 ~ 20mg per day. According to the fortified amount of iron fortified soy sauce and the average consumption of soy sauce in China at present, eating 10 ~ 15ml of iron fortified soy sauce every day can supplement 3 ~ 4mg of iron, which is only 30% ~ 40% of the daily iron requirement of human body. "Moreover, the human body itself also has a certain excretion effect on excessive iron." Chen Junshi affirmed, "Everyone can eat iron fortified soy sauce, and adult men should not be afraid. They will have no problem eating for a lifetime. "
What is iron fortified soy sauce? Iron deficiency is considered to be the top of the three "hidden hunger" (micronutrient deficiency) in the world, and about15 people in the world suffer from iron deficiency anemia. According to the survey of China Center for Disease Control and Prevention, the anemia rate of children in China is about 25%, that of women is about 20%, that of pregnant women is as high as 35%, and that of adult men is about 10%. Worryingly, iron deficiency anemia is already a clinical manifestation of severe iron deficiency, and the number of iron deficiency patients is much higher than this ratio.
Iron deficiency and anemia generally have no obvious symptoms except in severe cases. Not only clinically, but even some patients themselves have not paid enough attention to its consequences. Iron deficiency and anemia seriously affect children's physical and intellectual development and their ability to engage in physical and mental work in adulthood, which is not only harmful to women of childbearing age, but also may affect the health of the next generation. Since iron deficiency will bring such serious harm, how should we supplement the human body's demand for iron? How to popularize China's iron supplementation measures and realize comprehensive iron supplementation?
Officials deny that eating iron-fortified soy sauce causes cancer. According to the Beijing Times, in view of the problem reported and reprinted by some media that "iron fortified soy sauce will interfere with the absorption and utilization of other trace elements, and at the same time cause children to be short in height and even lead to cancer", the statement issued by the Food Fortification Institute of China Center for Disease Control and Prevention the day before yesterday said that there is sufficient scientific evidence to prove that adding a small amount of NaFeEDTA (sodium iron ethylenediamine tetraacetate) to soy sauce will not cause cancer and will not reduce the absorption of other trace elements by human body.
Sources of iron in food
The rich sources of iron (iron-containing food) are bovine kidney, caviar, chicken offal, cocoa powder, fish powder, liver, potato, polished rice, soybean powder, wheat bran, wheat germ and wheat-soybean mixed powder.
Good sources are beef, brown sugar, clam meat, dried fruit, egg yolk, pig kidney and sheep kidney.
Good sources: lean meat, brown sugar, egg yolk, pig kidney, sheep kidney, dried fruits (dried apricots and raisins), beer yeast, seaweed, brown sugar paste and wheat.
General sources: fish, grains, spinach, lentils, peas, mustard leaves, broad beans and melon seeds (pumpkins, zucchini and other seeds).
Trace sources: dairy products, vegetables and fruits.
In addition, cooking tomatoes or other acidic foods in a cast iron pot can also supplement iron, and the pot will put healthy iron into the food.
It seems that many foods contain iron, but many people in China are seriously deficient in iron, mainly women, children and the elderly. It is essential to supplement iron scientifically every day.
Vitamin C, an element that promotes absorption.
Vitamin C is a reducing agent, which not only has antioxidant function, but also can reduce trivalent iron to divalent iron, which is more easily absorbed and utilized by human body. At the same time, vitamin C can also synthesize unstable ferrous ascorbate with iron complex, and release iron from other combinations, thus promoting the absorption of colored hemoglobin iron and increasing the body's resistance to diseases.
We have included the vitamin C content of common foods in the table. You can arrange your own meals according to the data provided in the table. vitamin A
Vitamin A can not only increase the body's resistance, but also improve the body's absorption and transportation of iron. B vitamins
Vitamin B2 can promote the absorption of iron in intestine, while vitamin B6 can improve the utilization rate of iron in bone marrow. In addition, B vitamins can also promote our appetite. However, it should be noted that folic acid and vitamin B 12 are not helpful for the treatment of iron deficiency anemia. copper
Copper can promote the absorption of iron. When copper is deficient, iron absorbed by small intestine decreases and hemoglobin synthesis decreases, which will directly lead to iron deficiency anemia in human body. animal foodstuff
The "meat factor" in fish, meat and poultry food is beneficial to the absorption of iron, which means that the iron supplement effect of meat food is better than that of plant food. There are two forms of iron in food:
Non-heme iron: Trivalent iron mainly combines with protein and organic acids to form a complex. This form of iron must be separated from organic matter and reduced to divalent iron before it can be absorbed. If there is more phytic acid or phosphoric acid in the diet, it will form insoluble iron salt with iron, which will affect absorption. Ascorbic acid and cysteine can reduce trivalent iron to divalent iron, which is beneficial to iron absorption.
Iron (Fe) is a component of hemoglobin, myoglobin and many enzymes in the body. Heme iron mainly exists in animal products, which is much better than non-heme iron, which accounts for more than 85% of iron in general diet. However, when ingested with animal protein and vitamins, it can improve the absorption of non-heme iron.
Iron demand, iron metabolism and iron deficiency anemia are discussed in section 127 anemia caused by erythropoiesis deficiency. Section 127 discusses iron-negative diseases.
Deficiency: Iron deficiency can lead to anemia, which is the most common nutritional deficiency in the world. Some infants, adolescent girls and pregnant women suffer from iron deficiency anemia due to insufficient iron intake. Anyone who loses blood will have iron deficiency. All people with iron deficiency need iron supplementation.
Poisoning: Excessive iron is toxic, which can cause vomiting, diarrhea and intestinal damage. When a person receives iron treatment for too long or too long, or receives repeated blood transfusions, or has chronic alcoholism, iron will accumulate in the body. Iron deficiency disease (hemochromatosis) is a potentially fatal but treatable hereditary disease, which absorbs too much iron; Affected 1 10,000 Americans.
Rumor: Spinach is high in iron.
People used to think that spinach had high iron content, but it was not.
A scientist found that the iron content of spinach was much smaller than the recorded value. So, he did a lot of experiments and the results were still the same, so he published an article. This article caused a sensation in the whole society, and other scientists conducted experiments one after another and found the same result.
It turns out that when the priest copied the grades, he clicked the wrong decimal point. Iron is the hematopoietic element of the human body, and women have an extra channel for discharging iron-menstruation, so iron is supplemented.
The amount should be greater than that of men. The daily intake of iron is 15 mg, which can keep the complexion rosy. Pig liver, pig blood and duck blood are the richest and best absorbed iron, and bean products, sesame seeds, mushrooms, fungus, kelp, laver and longan also contain more iron. In addition, eating fortified soy sauce containing iron also has a good iron supplement effect. Iron is a component of cytochrome and non-heme ferritin in photosynthesis, biological nitrogen fixation and respiration. Iron plays an electron transfer role in the redox process of these metabolism. Because some chlorophyll protein complexes of chloroplasts need iron, lack of iron will lead to green deficiency between veins. Contrary to magnesium deficiency, iron deficiency occurs in young leaves because iron is not easily transferred from old leaves. Iron deficiency time is too long or even too long, the veins of leaves are green, and the whole leaves are albino. The yellow leaf disease of fruit trees in northern China is caused by iron deficiency.