How much iron do we have in our bodies? What are these irons for? Where did it come from and how was it lost? How do we make up the iron? Does iron pot cooking have anything to do with iron supplementation? This paper will discuss these issues.
Iron is one of the most common elements in nature. It was born in the center of a huge star and is the ultimate product of nuclear fusion reaction of the star. With the explosion of supernovae, iron and other elements were scattered everywhere, forming the earth and making us.
By mass, iron is the most abundant element on the earth, and the total mass of the earth is about 5.98× 10 kg, including iron (32. 1%), oxygen (30. 1%) and silicon (15./kloc-0). Because most of the iron sinks into the earth's core, the iron content on the earth's surface is only 5% of the earth's crust, ranking fourth after oxygen, silicon and aluminum. Iron is chemically active and easily loses the outermost electrons, so the iron on the surface basically exists in the form of iron oxide or other compounds. It is difficult for you to find pure iron in nature. Most of them are in iron meteorites. In fact, most of them are alloys of iron, nickel and a few other elements.
The iron content in human body is related to the nutritional level. In countries with high living standards, the iron content in people is higher. Generally speaking, adults contain about 4 to 5 grams of iron (about 38 mg iron/kg body weight for women and 50 mg iron/kg body weight for men). You're right, women have lower iron content. Anyway, all the iron in an adult's body adds up, and he can only hit such a nail:
Although there is very little iron in our body, we can only hit a nail, but its role in the body is indispensable. In other words, although iron is scarce, it is the decisive element to maintain our lives.
More than half (about 2.5 grams) of iron exists in our blood, and each milliliter of blood contains about 0.5 mg of iron, which is an important part of hemoglobin. Most of the remaining iron (about 2g for adult males and slightly less for women of childbearing age) is contained in ferritin complex, which exists in all cells, but is most common in bone marrow, liver and spleen. Ferritin stored in the liver is the main physiological source of iron reserves in the body, and ferritin is also one of the foundations of all living things.
The survival of human cells needs oxygen, and the transportation of oxygen in the body depends on iron. After oxygen is inhaled into alveoli, it is exchanged to red blood cells in blood, and hemoglobin in red blood cells is responsible for combining with oxygen; When oxygen is delivered to muscle cells in the body, iron-bound myoglobin is responsible for regulating the release of oxygen.
We lose about 1 mg of iron every day on average, which is about two milliliters of iron in blood. Women lose more iron every day at a certain stage, about 2 mg. Under normal circumstances, iron will be lost with the shedding of sweat, dander and gastrointestinal intima, and sometimes some iron will be lost in our body due to accidental bleeding.
If the sudden loss of iron is caused by massive hemorrhage, our body will quickly start the emergency mechanism, and ferritin in the liver will release a large amount of iron and supplement it to blood cells to maintain the lack of heme in the blood.
Bone marrow accounts for 4% of the total body weight. It is a hematopoietic organ, and human bone marrow produces about 500 billion blood cells every day. When iron deficiency occurs, the number of blood cells produced by bone marrow will decrease. With the aggravation of iron deficiency, the cells produced by bone marrow will become smaller.
When our body begins to lack iron, there are usually no symptoms, because ferritin, which stores iron in our body, releases iron and supplements it in the blood. However, if iron is not continuously and effectively supplemented, hemoglobin in the blood is not enough to deliver the oxygen needed by the body, which will show iron deficiency anemia.
Iron circulates in the body first, and the iron in those dead cells will be separated and reassembled into protein, so we only lose a tiny part of it. This doesn't mean that we don't need iron supplementation. We will separate iron ions from our diet and absorb and supplement our body by digesting the food we eat every day.
Iron is one of the important elements in the process of biological life, so it is ubiquitous in our food. Generally speaking, seafood, leafy vegetables, beans, bean sprouts and bean products, including red meat, poultry, fish and oysters, all contain iron, which is our important source of iron supplement. As mentioned above, the content of iron in animal liver, lean meat and blood products is high.
The absorption of dietary iron by human body is a dynamic process. Compared with our intake, the amount of iron absorbed by the body is usually low, which depends on the environment and the type of iron, generally in the range of 5 ~ 35%. The efficiency of absorbing iron depends on the source. The absorption of iron and other minerals usually occurs in the duodenum, and intestinal cells have special molecules that allow them to transfer iron into the body. Heme protein or iron must exist in the form of iron. Iron reductase on the brush edge of intestinal cells will reduce trivalent iron to divalent iron, which will be absorbed, stored and utilized by our bodies.
For our bodies, metallic iron is toxic and we won't absorb it. Under normal circumstances, iron will remain at a normal level in our body. If the ferritin level drops, the intestine will absorb more iron from food to supplement it, thus balancing this decline. Whether it is iron deficiency in the body or excessive iron supply caused by mistake, it will cause harm to body organs.
There is often a saying that frying in an iron pan can supplement iron in the body. This is obviously a wrong understanding. They confused the iron in the pot with the ferrous ions in our bodies.
There are a lot of ready-made iron ions in our food, which are easily absorbed by molecules in the intestine. On the contrary, our intestines and stomach can't absorb the iron filings scraped out of the pot.
You may say that when we are cooking, the iron in the wok will react with acetic acid to produce ferrous acetate, and the iron ions in ferrous acetate can be absorbed by us!
First of all, acetic acid is a weak acid. The content of acetic acid in our vinegar is generally 5%, which has been diluted to a very low concentration. And only in the case of iron powder will iron react with concentrated acetic acid for a long time to generate ferrous acetate. Even if we produce this compound in the cooking process, its amount is negligible.
There is a lot of iron on the earth, but there is very little iron in our bodies. The iron in an adult's body is only enough to nail a nail 5 cm long.
So a little iron in the body plays an extremely important role in our life. Iron (mainly ferrous iron) exists widely in our blood cells and body proteins, and anemia is one of the diseases caused by iron deficiency.
We usually supplement iron through diet. Iron is widely found in food, especially meat and beans, and it is more easily absorbed by the intestine.
It is wrong to try to make up iron through an iron pot. Iron supplement mainly depends on vegetables, not pots.