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Iron is a vital mineral that is, among other things, of immense importance for an optimal oxygen supply in the body (1). ...Show full detailsOriginal price €12,90Original price €12,90 - Original price €12,90Original price €12,90Current price €11,48€11,48 - €11,48Current price €11,48|/Save 11% now Save now
What is it and where does it come from?
Iron is the most abundant element on earth and is an essential trace element for humans. It is found in many different foods, including meat and vegetables, and can also be added to food through the use of cast iron pots and pans. In supplements, iron is present in many different forms, of which ferrous succinate and ferrous sulfate are best absorbed by the body, although ferrous sulfate can cause stomach problems. Ferrous gluconate and ferrous fumurate are good alternatives. Furthermore, a hydrolyzed protein chelate form called ferritin is also available. In the body, iron is primarily stored in the bone marrow, spleen and liver.
Iron has the atomic number 26 in the periodic table of the elements and the chemical symbol Fe. Together with cobalt and nickel, it belongs to the ferromagnetic metals. It occurs in nature both in pure form as a metal and in a variety of chemical compounds. In these chemical compounds iron occurs as bivalent or trivalent iron (Fe2+ or Fe3+). Iron belongs to the trace elements and is the most abundant of these in the human body. The total amount of iron in adults is about 4,000 to 5,000 mg, i.e. 4-5 g, of which about 2,500 mg, i.e. 2.5 g are in hemoglobin. The rest is in the iron depots (about 1,000 mg) and in myoglobin. There are about 8 mg in the iron-containing enzymes. A whole epoch of human history (from about 800 to shortly before the birth of Christ) is named after this element. During this period, man discovered iron as an important raw material for tools and, unfortunately, weapons.
The most important function of iron is to bind oxygen to the molecule hemoglobin in the red blood cells. In this way, oxygen is transported from the alveoli (air sacs in the lungs) in the blood to the body's cells. An iron deficiency impairs the formation of hemoglobin, resulting in the most common form of anemia, iron deficiency anemia. One of the consequences of this is an insufficient supply of oxygen to the organism. As mentioned above, iron is needed for the synthesis of heme and thus hemoglobin. Hemoglobin is the red blood pigment in erythrocytes, the red blood cells. It is composed of approximately 94% globin protein and 6% heme, to which iron is bound. Iron bound to hemoglobin binds oxygen and thus transports it from the lungs to all cells of the organism. On the "way back", hemoglobin transports carbon dioxide from the cells back to the lungs, where it is then excreted with the breath. Carbon dioxide is produced as a combustion product of cellular metabolism. In the immune system's fight against pathogens, iron plays another important role, on the one hand as a component of many enzymes, and on the other hand the pathogens themselves also need iron to survive. The availability of iron for bacteria persisting in the cell and their host is in a finely regulated balance. On the one hand, host cells need iron as a cofactor to fight pathogens, especially in the production of aggressive oxygen and nitrogen radicals. On the other hand, intracellular pathogens depend on iron and thus on host iron stores for their growth. Experiments have shown that both a deficiency and an excess of iron impair the body's scavenger cells (macrophages) in their ability to control bacterial pathogens. The biological availability of iron varies depending on the composition and type of food. For example, iron in bivalent form is well absorbed by the body such as ferroheme found in meat (consists of protoporphyrin u. Fe2+). Vegetable iron (vegetables, salads and fruit), on the other hand, is present in trivalent form. It must first be reduced to divalent iron and is therefore more difficult to absorb in the intestine. Therefore, much larger amounts of iron-containing foods must be consumed if the diet is exclusively vegetarian.
Iron absorption occurs in three steps:
- Uptake from the intestine into the mucosa cells (mucosal cells)
- Protein-dependent transport and storage in mucosa cells.
- Delivery of iron to transport proteins of the blood
The organism is able to adapt the resorption to the respective iron requirement. In the case of an increased iron requirement, the resorption rate can be increased to about 40 percent, whereas in the case of a high iron stock, it can be reduced to about 5 percent. On average, about 20 percent of iron is absorbed from animal foods and about 3 to 8 percent from plant foods.
Foods containing iron
Bread, meat (especially pork liver) and sausages are the most important sources of iron supply. The degree of utilization is important for iron intake, therefore meat is one of the most important suppliers. Iron from meat is absorbed much better than iron from plant products, of which, depending on the plant, only between 2 and 10% of the iron contained can be absorbed and utilized in the human intestine. Vegetarians and vegans should therefore pay particular attention to the adequate supply of iron. By vegans we mean vegetarians who abstain from all animal products, including eggs and milk. It may be necessary for vegetarians and especially for vegans to additionally supply iron in the form of iron-containing preparations.
In this context, it must also be pointed out that a purely vegetarian diet for children does not usually provide the necessary amount of iron. Particularly in the case of children, who have an increased iron requirement for healthy growth and optimum development of mental abilities, an undersupply of the trace element can have far-reaching consequences.
Foods with high iron content and resorbtion inhibiting substances or conditions.
- Spinach has a high oxalic acid content, which has an inhibitory effect on resorption.
- Soybean, it has a high content of resorbtion inhibiting phosphate. This is particularly tragic because the soybean is a food with very high iron content.
- Milk and dairy products inhibit the resorption of iron because of their high calcium content. Resorption-inhibiting substances or conditions
- certain dietary fibers (for example bran)
- Oxalates (for example spinach, rhubarb, cocoa)
- Protein deficiency in the diet
- Tannins (for example tea, coffee)
Along with iodine deficiency, iron deficiency is the most common mineral deficiency in industrialized countries, and iron deficiency anemia is the most common iron deficiency disease worldwide. In general, however, severe iron deficiency is very rare in Europe, but mild to moderate iron deficiency affects many people, especially women (the figures vary between 20 and 50%). It can occur, for example, in the case of a strongly unbalanced diet (diet, no meat) as well as through the predominant intake of poorly utilizable iron compounds. Iron can also be lost through heavier bleeding, for example during menstruation, through injuries and through frequent blood donations. Diseases in the gastrointestinal tract can impair iron absorption, for example through inadequate conversion processes. Iron deficiency also occurs in the context of certain diseases (e.g., infections, hormonal disorders rheumatism, cancer, or may be caused by drugs (e.g., antibiotics, some painkillers and anti-inflammatory drugs). A deficiency of vitamin B6 may contribute to iron deficiency. Symptoms of iron deficiency include lack of physical and mental performance, fatigue, weakness, headaches, sensitivity to weather, nervousness, and irritability. Paleness, brittle, rough skin and brittle hair may occur, grooves in fingernails and cracks in the corners of the mouth may form. Further, palpitations, shortness of breath, burning of the tongue and constipation may develop. Iron deficiency also prevents the activity of important enzymes, which in turn are involved in many bodily processes and are thus impaired. Furthermore, thermoregulation (heat balance of the body) is disturbed, immune deficiencies may occur and susceptibility to infections may increase. There is a warning about the risk of premature birth in pregnancies. This is significantly higher in women suffering from iron deficiency. The risk of stillbirth also increases.
Safety and side effects
Iron is probably safe and harmless for most people when taken orally in appropriate amounts. However, it can cause side effects including stomach upset, stomach pain, constipation, diarrhea, nausea and vomiting. Taking iron supplements with food appears to reduce these side effects. However, food can also reduce iron absorption. For this reason, iron should be taken on an empty stomach if possible. If it causes too many side effects, it can be taken with food. One should try not to take iron in combination with foods that contain dairy products, coffee, tea, or cereals. There are many forms of iron products such as ferrous sulfate, ferrous gluconate, ferrous fumarate and others. Some iron products, such as products containing a polysaccharide iron complex, are claimed to cause fewer side effects than other iron products. However, there is no scientific evidence to support these claims. Some enteric-coated iron products or delayed-release iron products could cause nausea in some people. These products are also more poorly absorbed by the body. Liquid iron supplements could stain teeth black. There are concerns that high iron intake could increase the risk of heart disease. Some studies show that people who consume a lot of iron - especially in the form of food sources such as red meat - are more likely to develop heart disease. This could be especially true for people who suffer from type 2 diabetes. However, these observations are controversial. Other studies do not show that iron increases the risk of heart disease. It is too early to make a conclusive statement about whether iron increases the risk of heart disease.
The maximum tolerated amount of iron - the highest intake at which no undesirable side effects are expected - is as follows:
- Children and infants under 14 years: 40 mg/day
- People 14 years and older (including pregnant and lactating women): 45 mg/day
These amounts do not apply to people undergoing medical treatment for iron deficiency.
Overdose and poisoning
As a side effect of increased iron intake, a dark coloration of the stool may occur, which has no medical significance. Other symptoms are weakness, blue coloration of lips, hands and nails, digestive problems, diarrhea, constipation, up to coma possible. Overdose rarely occurs; too much iron is excreted in healthy individuals. Nevertheless, accidental ingestion of larger quantities of iron-containing drugs or preparations can lead to iron poisoning. This is rare in adults, but in children these accidents, which can have a fatal outcome, are more common. The fatal dose is about 35-630 mg/kg body weight (commercially available iron tablets contain about 40 to 100 mg of iron each). Thus, in infants with a body weight of 10 kilograms, as few as 5 iron tablets may be fatal. The symptoms of acute iron poisoning occur about 30 to 120 minutes after ingestion and consist of violent vomiting, severe stomach pain and diarrhea. Due to the high fluid losses, a shock situation can occur that can lead to death. Once patients have recovered from the initial symptoms, they may experience a severe drop in blood pressure, convulsions and severe liver inflammation about a day later. In case of iron overdose, drinking milk is recommended, which allows the formation of iron-protein complexes, i.e. the binding of iron to proteins contained in milk.
Precautions and warnings
Pregnancy and Lactation: Iron is probably safe and harmless for pregnant and lactating women who have enough iron stored in their bodies when used below the maximum tolerated amount of 45 mg of elemental iron per day. Higher amounts are probably not safe and harmless when taken orally. Unless one suffers from an iron deficiency, one should not take more than 45 mg of elemental iron per day. Higher dosages regularly cause gastrointestinal side effects such as nausea and vomiting. High hemoglobin levels at the time of delivery are associated with problems during childbirth. Hemoglobin is the molecule in red blood cells that contains iron.
Diabetes: There is concern that a diet rich in iron may increase the risk of heart disease in women with type 2 diabetes, although this has not yet been proven. If you have diabetes, you should talk to your doctor about your iron intake.
Stomach and intestinal ulcers: Iron can cause irritation and aggravate these conditions.
Inflammation of the intestines such as ulcerative colitis or Crohn's disease: iron could cause irritation and aggravate these conditions.
Hemoglobin disorders such as thalassemia: Taking iron could result in excessive amounts of iron in the body in people suffering from these disorders. For this reason, people suffering from such a disease should not take iron supplements unless prescribed by a physician.
Premature infants: Administration of iron to premature infants with low blood levels of vitamin E can cause serious problems. Vitamin E deficiency should be corrected before iron is administered. For this reason, iron administration to premature infants should be discussed with a physician.
Care should be taken when combining iron with the following medications
Antibiotics (Quinolone antibiotics)
Iron could reduce the amount of antibiotics the body absorbs. Taking iron in combination with quinolone antibiotics could reduce the effectiveness of these antibiotics. To avoid this interaction, iron should be taken two hours before or two hours after antibiotics.
Antibiotics (Tetracylin antibiotics)
Iron may bind to tetracyline antibiotics in the stomach and reduce the amount of tetracyline antibiotics the body can absorb. Taking iron in combination with tetracyline antibiotics could reduce the effectiveness of tetracyline antibiotics. To avoid this interaction, iron should be taken two hours before or four hours after taking tetracyline antibiotics.
Iron may reduce the amount of bisphosphonates that the body absorbs. Taking iron in combination with bisphosphonates may reduce the effectiveness of bisphosphonates. To avoid this interaction, bisphosphonates should be taken at least 2 hours before iron or later in the day.
Levothyroxine is used for hypothyroidism. Iron may reduce the amount of levothyroxine that the body absorbs. Taking iron in combination with levothyroxine could reduce the effect of levothyroxine.
Penicillamine is used in Wilson's disease and rheumatoid arthritis. Iron may reduce the amount of penicillamine that the body absorbs. Taking iron in combination with penicillamine could reduce the effect of penicillamine. To avoid this interaction, iron should be taken two hours before or two hours after penicillamine.
Iron is important for the production of red blood cells. Chloramphenicol could reduce the formation of new red blood cells. Long-term use of chloramphenicol could reduce the effects of iron on red blood cell formation. However, since most people take chloramphenicol for only a short period of time, this is not a major problem.
There are a number of reasons for which the daily iron requirement is not covered, or from which an increased iron requirement results. These are mainly pregnant and breastfeeding women, or people who do not absorb enough iron due to their dietary habits. To prevent possible diseases caused by iron deficiency, it is necessary in these cases to take additional iron supplements. However, these preparations should only be taken for a limited period of time, because in a healthy person, once the iron stores have been replenished, a permanent supply of iron in the form of medicines is not necessary. Individuals suffering from chronic iron deficiency without malnutrition or nutritional deficiency should be examined for chronic blood loss in the gastrointestinal tract.
The German Nutrition Society recommends 10 to 12 mg of iron for a healthy diet for people from the age of 8. From the onset of menstruation until menopause, women should consume slightly more, namely 15 mg of iron, due to the monthly blood loss. Pregnant and breastfeeding women have a particularly high iron requirement. Their requirement is about 30 mg for pregnant women and 20 mg for breastfeeding women. Gynecologists usually recommend taking iron supplements because this requirement cannot always be covered by food. Additional iron requirements may occur in growing children, seniors, athletes, vegetarians, frequent blood donors, and a number of diseases (e.g., blood disorders, rheumatism, and tumors), among others. Vitamin C, some amino acids and fructose, for example, improve the absorption of iron. Often, therefore, the iron in iron supplements is contained in combination with vitamin C. In contrast, other substances, such as tannins from coffee or tea and oxalic acid from spinach, inhibit the absorption of iron from food.
Demand in sport
Since the unhindered transport of oxygen within the body and the function of iron-containing enzyme systems in energy metabolism are important prerequisites for peak physical performance, iron is an important trace element for athletes. An insufficient supply leads to a noticeable drop in performance. The normal iron requirement is 1.5 to 2 mg daily. However, the iron requirement of the athlete is increased up to twice the normal. My recommendation is to take a dose of 30 to 40 mg a day, if possible through food. Take supplements only if prescribed by a doctor.
- Diebschlag W (1985) The optimal diet for athletes. Competitive Sports 1/85
- Findlay S, Podolsky D, SilbernerJ (1992) Iron And Your Heart. U.S. News & World Report 09/21/1992.