The Trace Element Iron

Author: Theres Eisenreich ‎‏‏‎ ‎‏‏‎ ‎|‏‏‎ ‎‏‏‎ ‎‏‏‎Published: 6. July 2022‎‎‏‏‎ ‎‏‏‎ ‎‏‏‎ ‎|‏‏‎ ‎‏‏‎ ‎‏‏‎ ‎Updated: 6. July 2022


The Trace Element Iron

Iron is not only the most common metal found on the earth's surface, but it is also a vital trace element without which we cannot exist. It is involved in various processes in the body, but one of its main tasks is to contribute to the transport of oxygen through the organism.

What Exactly Does Our Body Need Iron For?

Our body cannot produce iron itself, so we have to take it in through our food. The intestine is the central absorption point for the trace element. It occurs in various compounds, but only the bivalent (Fe2+) and trivalent (Fe3+) iron are important for our body.

Iron is an essential building block of haemoglobin (red blood pigment) and is therefore significantly involved in the transport of oxygen from the lungs to the corresponding tissues. Excess iron is stored in the muscles, liver and spleen, among other places. If there is enough iron, it contributes to physical and mental performance and reduces tiredness and fatigue. It also ensures healthy functioning of the immune system and is involved in cell division.

In addition, iron plays an outstanding role in signal transmission between the nerve cells. Here, neurotransmitters are the messenger substances through which the nerve cells communicate with each other. Iron is involved in the production of these neurotransmitters.

Schaubild zu den Wirkungsweisen von Eisen im Körper

Risk Groups For Iron Deficiency

An iron deficiency can occur above all in special life situations or circumstances. The risk group primarily includes women of childbearing age who menstruate regularly and perhaps heavily. In addition, pregnancy and breastfeeding also require more of the trace element. Therefore, special attention is paid here gynaecologically.

But competitive athletes, especially those in the endurance field, also have a particular tendency to iron deficiency. Microhaemorrhages in the tissue can be to blame, but increased muscular strain, increased sweating and reduced iron absorption in the intestine due to constant physical stress can also promote an iron deficiency.

Due to their diet, vegetarians and vegans also belong to the risk group for iron deficiency, as they lack animal foods as well-bioavailable sources of iron. But people who donate blood, are chronically ill or have had an operation also belong to the risk group for iron deficiency, as do growing children or babies who are not breastfed.

Difference: Iron Deficiency And Iron Deficiency Anaemia

One speaks of an iron deficiency when the body has too little of the trace element for its daily needs. Sometimes it happens that the usual diet does not cover the amount of iron needed. The daily iron requirement is also increased in the special (life) situations mentioned above. All these factors can lead to an iron deficiency and subsequently to a disorder of the iron metabolism. An iron deficiency can occur when:

• You lose a lot of iron, for example during menstruation or other bleeding periods
• You have an increased need for iron, such as during pregnancy or breastfeeding
• Iron absorption is reduced, as can be the case with vegan or vegetarian diets

Iron deficiency anaemia, also called anaemia, describes a disorder of the entire haematopoietic system, which can develop due to an iron deficiency. The red blood cells and haemoglobin are reduced because the previous iron deficiency causes a disturbance in the production of the red blood pigment haemoglobin.

Iron deficiency and the symptoms

These symptoms can indicate an iron deficiency, among other things:

• Frequent fatigue
• Powerlessness
• Lack of concentration
• Frequent headaches
• Sleeping disorders
• Fast heartbeat
• Shortness of breath during exertion/sport
• Brittle nails and hair as well as hair loss
• Torn corners of the mouth (rhagades)
• Paleness

Anyone who observes these symptoms should have a blood check done by a doctor or therapist to detect or rule out an iron deficiency.

Übersicht der Symptome eines Eisenmangels

Avoid self-diagnosis of iron deficiency

As the table below shows, boys and men need less iron than girls and women from the age of 10. For this reason, the male sex should at best not take iron in addition without a doctor's instruction. But girls and women should not diagnose themselves with an iron deficiency simply because they have a few typical symptoms. A blood count and a therapeutic recommendation for additional iron supplementation should be made in advance.

These parameters can be checked when an iron deficiency is suspected

To be sure that an iron deficiency is really present, a look is taken at the blood serum, the blood plasma or even the whole blood, depending on the parameter examined.


Iron-containing protein; red blood pigment and main component of red blood cells

Normal values:
Women: 115-160 g/l
Men: 135-178 g/l


Percentage of all blood cells in total blood

Normal values:
Women: 36-48 vol%
Men: 40-53 vol%


Transport protein of iron in the blood to transport it to the tissues.

Normal values:
Transferrin: 2.0-3.6 g/l
Transferrin saturation* : 16-45 %.
Soluble transferrin receptor**: 0.8-2.3 mg/l

* Indicates how much of the transport protein has iron bound, how "saturated" it is.
** Is responsible for transporting transferrin into the cell.


Protein molecule within cells that can store iron; each ferritin molecule can store about 4,000 iron molecules.

Normal values:
16-19 years: 10-163 µg/l
20-60 years: 9-140 µg/l
over 60 years: ≥ 13 µg/l

16-19 years: 12-178 µg/l
20-60 years: 18-360 µg/l
over 60 years: ≥ 21 µg/l

Iron Requirement Per Day - Who Needs How Much?

Ideally, we get iron regularly from our food. The intestine is the central point of absorption of the trace element. It occurs in various compounds, but only the bivalent (Fe2+) and the trivalent (Fe3+) iron are important for our body. Unlike most other minerals, the requirement for iron changes over the course of a lifetime and is also dependent on gender:

Infants and children
(0 to under 4 months)
0.5 mg/day
(4 to under 12 months)
8 mg/day
(1 to under 7 years)
8 mg/day
(7 to under 10 years)
10 mg/day
Boys and girls
Boys (10 to under 15 years)  12 mg/day
Girls (10 to under 15 years) 15 mg/day
Adolescents and adults
Male adolescents (15 to under 19 years) 12 mg/day
Male adults (19 years and over) 10 mg/day
Female adolescents and adults (15 to under 51 years) 15 mg/day
Female adults (51 years and over) 10 mg/day
Pregnant and breastfeeding women
Pregnant women 30 mg/day
Breastfeeding women 20 mg/day

Foods Containing Iron

People who eat a balanced diet usually automatically have a lot of iron-rich foods on their plates. Nevertheless, some provide more, others less of the vital substance. We will take a closer look at which foods have which iron levels in the following:

Plant-based foods Iron content (mg)
per 100 g food
Cocoa powder (lightly de-oiled) 12.0 - 15.0
Millet 9.0
Lentils 7.5
Chickpeas 6.9
Peas 5.2
Oatmeal 4.6
Green spelt 4.2
Spinach 4.1
Wholemeal bread 3.15
Animal foods Iron content (mg)
per 100 g food
Pork liver 18.0
Beef liver 7.1
Oysters 6.25
Blood sausage 6.1
Pork tenderloin 3.0
Turkey 3.0
Cured pork 2.5
Beef fillet 2.3
Eggs 2.1

Iron From Plant Or Animal Sources - What Is The Difference?

As you can see in the overview, the important trace element iron is contained in many foods - and especially in plant-based foods. Now, as a vegan or vegetarian, you might say: "Great, that's no problem to cover my daily requirement through food!" Unfortunately, it's not that simple. Because animal iron is actually much more bioavailable, i.e. better absorbed by the body, than iron from plant sources.

In the various foods, iron is present in two forms: as non-haem iron (mostly trivalent iron, Fe3+) and as haem iron (divalent iron, Fe2+, as a complex with the haem pigment of haemoglobin). Now, however, haem iron is better absorbed by the body and this is found exclusively in animal foods. In plants, only non-haem iron is present. This iron (mostly Fe3+) has to share its transporter in the intestinal cell membrane with other substances (for example, with zinc or magnesium) after conversion to Fe2+ and the body can therefore absorb it less easily. However, the intestinal cells have their own transporter for haem, and thus also for haem iron, so that this form of iron is better absorbed.

Vitamin C Can Improve Iron Absorption In The Body

To improve the body's absorption of non-haem iron from plant foods, vitamin C is the keyword. When iron-rich foods are combined with vitamin C-containing foods, the vitamin ensures that the iron is converted into a form that can be directly absorbed by the intestine. For example, vegetables containing vitamin C, such as kale, peppers or broccoli, or a glass of orange juice (pressed by oneself or as direct juice) with a meal are good choices. However, in order to actually positively influence iron absorption through vitamin C, a meal should contain at least 25 mg of the vitamin, preferably even more. This corresponds to about 100 g of ripe tomatoes or the same amount of raspberries.

Good to know: Sensitive vitamin C

If there is one thing that the valuable vitamin C does not like, it is high heat, long storage and a lot of light. All this drastically reduces the vitamin C content of a food. Therefore, gentle cooking or raw consumption and direct consumption after shopping of fruits and vegetables is highly recommended.

What Can Inhibit Iron Absorption?

However, iron absorption, especially from plant sources, can also be blocked. Here, the composition of the food during a meal plays a major role. For example, dairy products or also tannins from tea and coffee can hinder iron absorption. Oxalic acid, which is contained in rhubarb, among other things, also binds iron and makes it unusable for the body.

What Should You Look Out For When Taking Iron Tablets Or Capsules?

If you have a low iron status and want to take a preparation to safely replenish your stores, you should make sure that the preparation is well tolerated. Many iron products have a negative effect on the gastrointestinal tract and cause complaints such as stomach pain or constipation.

In addition, the dosage and release of iron also play an important role: Depending on the need and also deficiency state, the preparation should ensure a sufficient supply of iron, which is, however, released slowly. This is gentler on the digestive tract and prevents too much free iron from entering the bloodstream. If the iron is released too quickly, there is more iron in the blood than can be bound by transferrin (iron transporter). Consequently, free iron remains in the blood, which promotes the formation of harmful oxygen radicals (oxidative stress).

Die Verträglichkeit eines Eisenproduktes ist für den Magen-Darm-Trakt wichtig.

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