The importance of iron


Iron is a mineral that is important for, among other things, the formation of hemoglobin, a component of red blood cells. Red blood cells transport oxygen through our body.

Iron is found in food in 2 forms: as heme iron and as non-heme iron. Heme iron is only found in animal products. Non-heme iron is found in animal and vegetable products. Heme iron is better absorbed.

People who are more at risk of an iron deficiency are: women of childbearing age, pregnant women and women who are breastfeeding. It is also important for young children and vegetarians to pay extra attention to iron. Iron deficiency can be recognized by fatigue, pale skin, restless legs and being quickly out of breath. In case of suspicion of iron deficiency, it is advisable to see a doctor.

What is iron?

Iron is a trace element that is important for the formation of hemoglobin, a component of red blood cells. Iron can be found in animal and plant products.

What contains iron?

Heme iron is only found in animal products such as meat, fish and chicken. There is more iron in beef or lamb than in pork or chicken. Non-heme iron is found in both animal products and vegetable foodstuffs, such as bread and whole meal products, legumes, nuts and dark green vegetables such as spinach, purslane, pak choi, endives and chard. Egg and meat substitutes contain only non-heme iron.

Iron per portion Milligram

Iron per portion Milligram
  Total iron Non-heme iron Heme iron
1 piece of beef steak (prepared, 70 grams) 1,9 0,6 1,2
1 slice of tofu (prepared, 75 grams) 1,7 1,7 0
1 hand of unsalted cashew nuts (25 grams) 1,7 1,7 0
1 boiled egg (50 grams) 1,2 1,2 0
1 large spoonful kidney beans (60 grams) 1,2 1,2 0
1 large spoonful of cooked spinach (50 grams) 1,2 1,2 0
1 salted herring (75 grams) 1,1 0,4 0,7
1 large spoonful of boiled whole meal paste (60 grams) 1,0 1,0 0
1 slice of whole meal bread (35 grams) 0,7 0,7 0
1 piece of chicken breast (prepared, 70 grams) 0,5 0,4 0,1
1 large spoon boiled kale (50 grams) 0,5 0,5 0

Incorporation of iron

Your body absorbs iron in the first part of the small intestine, the duodenum. The absorption of iron from the diet varies and depends on the form in which it occurs in the food (heme iron or non-heme iron), the presence of other nutrients and the iron supply in your body.

Absorption of heme iron

On average, the body absorbs about 25% of heme iron from a diet.

Absorption of non-heme iron

The amount of non-heme iron your body absorbs can vary between 1 and 10%. This depends on the solubility of the non-heat iron in the small intestine. The more soluble it is, the better it is absorbed. Certain substances in the diet increase the solubility and thus the absorption of non-heat iron. Other substances together with non-heme iron form an insoluble complex so that the non-heme iron is absorbed less well.

What role do other nutrients play in the absorption of iron?

Vitamin C ensures that non-heme iron from plant sources is better absorbed by the body. If you eat vegetables or fruit with every meal, your body absorbs iron more easily.

In addition, the following substances reduce the absorption of non-iron:

  • Phytate in grains and legumes
  • Polyphenols in tea or coffee

Calcium reduces the absorption of heme iron and non-heme iron.

The effects of these nutrients on the absorption of iron have often been studied on their own. If you look at the total diet in the long term, there are no specific nutrients you need to avoid because of an inhibiting effect on the absorption of iron. With a varied diet you also get food that stimulates the absorption and can remove the inhibiting effect. This has been taken into account when determining the recommended amounts of iron.

What does the iron supply mean for the absorption in the body?

The amount of iron in the body is 3 to 4 grams. About 25% of this is stored in liver, spleen and bone marrow. The iron supply is the most important factor that determines how much iron is absorbed. As the supply decreases, the absorption of iron by the body from the small intestine increases. Research has shown that the absorption of heme iron is increased to more than 42% when stocks are almost exhausted.

How much iron does your body absorb?

The absorption of the total amount of iron from an average western diet is estimated at more than 15%. On average, a vegetarian takes up 10% iron from the diet, because they mainly take in the non-heme iron that the body absorbs less well.

What is iron good for?

Iron is important for the formation of hemoglobin, a component of red blood cells. Red blood cells transport oxygen through our body. Iron is also needed to produce energy in our cells and iron contributes to the normal functioning of the immune system.

Symptoms of iron deficiency

You can recognize an iron deficiency by it:

  • quickly tired
  • pale skin
  • quickly out of breath
  • suffer from restless legs, an urge to move them

Often these symptoms of iron deficiency occur even before there is anaemia. Do you have these symptoms for a longer period of time? Then go to your family doctor.

Iron deficiency can be recognized by: quickly tired, pale skin, quickly out of breath, restless legs.

Consequences of iron deficiency in children and pregnancy

Children need enough iron to develop their thinking skills and muscle coordination. In young children, iron deficiency can lead to a less functioning memory and disturbed learning behavior.

Women who are just pregnant, iron deficiency can lead to a shorter pregnancy period.

Chance of iron deficiency

The chance that someone has an iron deficiency is not so great. The body itself ensures that it gets more iron from food when there is a shortage. The most serious form of iron deficiency is anemia.

There are some groups that have a higher risk of iron deficiency: girls / women of child-bearing age, because they lose blood when they have their period, and women who are pregnant or breastfeeding. Also, for young children and vegetarians it is important to pay extra attention to iron.


Iron deficiency is often associated with anemia due to low hemoglobin levels in the blood. Anemia is not always and only the result of an iron deficiency. A low hemoglobin level in the blood can also be caused by a deficiency of folic acid or vitamin B12 or as a result of internal blood loss, for example due to an infection. Also, in case of an inflammation in the small intestine, such as celiac disease or crohn’s disease, the hemoglobin level in the blood can be low. The body then does not absorb the iron properly in food. Studies abroad show that a real iron deficiency, resulting in anemia, is almost non-existent in Western countries. With certain diseases, such as malaria, extra iron does more harm than good. It is therefore important to take iron tablets only after consultation with the doctor.

Too much iron

Too much iron can be harmful to the liver. This may increase the risk of liver cancer, cardiovascular disease and type 2 diabetes. When swallowing more than 45 milligrams of iron a day, acute gastrointestinal problems such as nausea, vomiting and diarrhea can occur.


People with the hereditary disease of hemochromatosis can quickly ingest too much iron. This condition occurs in about 0.5% of the population. Hemochromatosis patients need an adapted diet. They certainly should not swallow iron tablets.

Nutritional advice

With a healthy and varied diet, most people get enough iron. Fill out the Disk of Five for you for a tailored advice.

Iron for vegetarian food

Vegetarians generally only receive non-heme iron, so the absorption by the body is somewhat lower. These groups sometimes have lower iron reserves than the general population, but that level is still sufficient. Therefore, there is no reason to recommend higher amounts of iron for vegetarians. When choosing meat substitutes, it is advised to take variants with sufficient iron. See what good meat substitutes are.

How much iron do you need daily?

Men have a recommended daily amount of 11 milligrams of iron per day. For menopausal women (between 16 and 50 years of age) this is 16 milligrams per day. For other ages, check the table below for the recommended daily allowance.

Category/Age Daily recommendations of iron (milligram)
6-11 months 8
1-2 years 8
2-5 years 8
6-9 years 9
9-13 years 11
14-17 years 11
18 years and older 11
9-13 years 11
14-17 years 15*
18-50 years (before menopause) 16*
Women after menopause 11
Pregnant women *
Women who are breastfeeding 15*

*There are groups that are more likely to have an iron deficiency:

– Girls/women of child-bearing age, because they lose blood when they have their period.

– Women who are pregnant or breastfeeding.

Therefore, the recommendation for these groups is higher. Pregnant women do not know exactly how much extra iron they need.

Can you get too much iron?

The European Food Authority (EFSA) has not derived an acceptable upper limit for iron. The Scandinavian Nordic Council applies an acceptable upper limit of 25 milligrams of iron per day from food and supplements for adults. The American Institute of Medicine 45 milligrams per day. It is almost impossible to get too much iron from food.

Iron pills

A varied diet provides enough iron for most people. The advice is not to take multivitamins or other supplements. If you do, do not take the recommended daily allowance (RDA) more than once. The RDA is on the label. It is not advisable to take iron pills with (much) more iron, unless your (family) doctor or midwife advises this.