Trace elements

Iron : all about this essential trace element

Iron is a trace element very present in the human body which contains between 2.5 and 4g. It enters into the constitution of hemoglobin and myoglobin, two proteins very involved in the oxygenation of the cells of the body. A lack of iron in the body usually results in anemia that can have serious consequences if left untreated.

Iron Characteristics:

  • Trace element abundant in the human body
  • In the diet, there are differentiated sources of heme iron and sources of non-heme iron
  • Heme iron from meat and fish is better assimilated
  • Iron deficiency anemia is very common and may result from low iron intake
  • Women of childbearing age and pregnant women have increased iron requirements

Why consume foods rich in iron?

Benefits and Roles of Iron

Heme and non-heme iron

In the diet, iron is found in two different forms: heme iron and non-heme iron.

  • Heme iron, which is bound to heme, is found in high quantities in meat, offal, fish and seafood. Its bioavailability is 25%. In other words, he is very well assimilated.
  • Non-heme iron comes from legumes, vegetables, oleaginous plants, tofu, eggs, etc. Its bioavailability is only 5 to 10%. We assimilate it less well than iron from animal products.

Ideally, and to avoid iron deficiency, it would be necessary to have a diet combining both types of iron.

Oxygenation of cells

Iron enters into the constitution of hemoglobin. Hemoglobin is found in red blood cells responsible for oxygenating the various organs and tissues of the human body.

Constitute myoglobin

It also forms myoglobin, a form of oxygen reserve in the muscle. Iron is very related to oxygen in the body. Therefore, among the common symptoms of anemia, there is shortness of breath or pallor.

Metabolic reactions

Iron is involved in many metabolic reactions, it is essential for the proper functioning of the body. It allows the synthesis of DNA and some neurotransmitters such as adrenaline or norepinephrine.

20 foods containing iron

Foods Servings (mg)
Braised pork liver100 g18 mg
Lamb or chicken liver, braised or sauteed100 g8-13 mg
Braised lamb kidneys100 g12 mg
Cooked soy beans250 ml (1 cup)9 mg
Oysters from the Pacific Ocean raw or steamed100 g (2-4 medium)5-9 mg
White beans and cooked lentils250 ml (1 cup)5-8 mg
Poultry offal stewed100 g6-8 mg
Beef liver braised or fried100 g6-7mg
Boudin cooked100 g6 mg
Braised or sauteed veal liver100 g5-6 mg
Red beans, chickpeas or lima beans, cooked250 ml (1 cup)3-6 mg
Tofu100 g5 mg
Horse100 g5 mg
Dehydrated Pumpkin and Pumpkin Seeds1/4 cup (60 mL)5 mg
Breakfast cereals30 g4 mg
Beef, roasted palette, braised100 g4 mg
Crushed tomatoes, canned250 ml (1 cup)3 mg
Boiled spinach125 ml (1/2 cup)3 mg
Shrimps, raw or cooked100 g2-3 mg
Canned clams100 g2.8 mg

How to use iron?

Use of iron

Iron Requirements

Recommended Dietary Allowance (ANC)
Babies 0-6 months0.27 mg *
Babies 7-12 months11 mg
Babies 1-3 years old7 mg
Children 4-8 years old10 mg
Boys 9-13 years old9 mg
Girls 9-13 years old9 mg
Boys 14-18 years old11 mg
Girls 14-18 years old11 to 16 mg
Men 19-50 years old11 mg
Women 19-50 years old11 to 16 mg
Men 50 and over11 mg
Women 50 and over11 mg
Pregnant women30 mg
Nursing women11 mg

* Sufficient contributions

Food supplements based on iron

There are many food supplements containing iron. Often indicated to prevent or treat anemia, they can also be used after digestive surgery, at the top athlete, pregnant women or people on a vegetarian or vegan diet. The dosage varies according to the problem and the context, the supplementation must be done under medical supervision.

Undesirable effects of iron

What happens when there is too much iron in the blood?

Excess iron in the blood can be pathological (hemochromatosis) or result in too much intake. Too much, iron has a pro-oxidative effect, that is, it promotes oxidative stress and premature aging of cells. It could be responsible, in the long run, for an increased risk of digestive cancers. Hemochromatosis can be responsible for hepatomegaly (enlargement of the liver) that can progress to cirrhosis and liver cancer.

Consequences of a lack of iron

Iron deficiency is much more common than excess iron. It causes anemia that quickly translates into a drop in certain blood levels. If anemia is related to a lack of iron, it is called iron deficiency anemia. This type of anemia is very common, especially in women who have increased needs for menstrual bleeding. This is also the case in some other situations at risk of malabsorption (chronic bowel disease, gastric surgery, etc.). Anemia is manifested by various symptoms: pallor, fatigue, shortness of breath, muscle weakness, hair loss, chills, dull skin, etc.

Interactions with other nutrients

Vitamin C increases iron absorption by the body. The presence of heme iron (from meat) in a meal increases the uptake of non-heme iron (from plants, eggs and dairy products) present in the same meal.

In contrast, tannins (mainly tea), phytates, fiber, calcium, magnesium and zinc reduce its assimilation. It is, for example, not recommended to consume tea around the meal to avoid the absorption of iron. In general, a varied and balanced diet can provide enough iron despite these interactions.

Chemical Properties

The iron symbol is Fe, its atomic number is 26. The atomic mass of iron is 55.845 u, its density is 7.874 g.cm-3. Iron is a gray-silver transition metal.

It is often found in combination with carbon to form steels to use the material in larger areas.

Nutrient History

Although very old, the use of iron in metallurgy remained secret until the twelfth century BC Since then, the use of iron will become massive and we even speak of “Iron Age” to designate the time. Since then, iron has been used in various fields (metallurgy, architecture, etc.) and its roles in the body have been studied by science. For example, currently the link between excess iron, oxidation and digestive cancers is the subject of in-depth scientific studies.