One of the best-known trace elements is of course iron! So much so that it is often placed in the category of minerals. But make no mistake, the amounts of iron in the body are trace amounts, making it a perfect trace element. Namely, there is not just one form of iron, but rather two. We find organic iron: heme iron, that is to say iron linked to the heme of red blood cells; as well as inorganic irons, this is divided into two forms: ferrous iron (Fe2+) and ferric iron (Fe3+). Heme iron is better absorbed than inorganic irons, making it more readily available to the body. Heme iron is found in meats, offal, fish, molluscs and crustaceans, ferrous iron is found in eggs and dairy products, and ferric iron in legumes, dried fruits, spices, algae and whole grains. No offense to Popeye, spinach is not a source of iron. This preconceived idea comes from a comma placement error. If it is not for this cartoon that iron is known, it is surely because of its deficiency. Frequent and serious, it leads to anemia with multiple consequences for the body. Conversely, excess iron is just as serious, leading, in extreme cases, to liver cancer. These two extremes show to what extent iron is a complex trace element, both in terms of its dietary origin and its absorption, not to mention its metabolism. Essential to life, it transports oxygen to all the cells of the body. It is therefore essential to ensure normal and frequent dietary intake of iron, through a varied and balanced diet in order to meet its daily needs.

  • Family: trace elements
  • Other name(s): Fe2+, Fe3+
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Calculate my daily iron requirement

I am :

In which foods can I find my daily iron intake?

Foods containing Iron Iron concentration (in µg/100 g) Quantity of food to cover my daily needs (in g)
Ao-nori, dried 234 ?
Thyme, dried 124 ?
Basil, dried 89.8 ?
Mint, dried 87.5 ?
Meloukhia powder 87 ?
Marjoram, dried 82.7 ?
Sea lettuce, dried 78.9 ?
Herbs of Provence, dried 69.8 ?
Cumin seeds 66.4 ?
Atlantic wakame, dried 61.5 ?

Properties of Iron

Iron is studied and recognized for the following main properties:

  • Antianemic : Iron plays a major role in the production of red blood cells. Indeed, it is an essential player in the proper functioning of erythropoiesis (mechanism for the formation of red blood cells: red blood cells), taking place in the bone marrow.

  • Oxygenator : Iron enters into the constitution of the heme of red blood cells (red blood cells) and myoglobins. Heme is a structure (called porphyrin), found four in number in a red blood cell, and only per myoglobin. It is thanks to the iron atom that red blood cells can fix, transport and release oxygen to all the cells of the body. Just as with myoglobins, muscle respiratory pigments, iron allows them to fix, store and release oxygen to the muscles.

  • Immunomodulating : Iron influences the body's reaction during an infectious state. Indeed, it promotes the formation of reactive oxygen species. These are toxic to pathogens. On the other hand, in excess, iron benefits infectious agents, explaining the non-automatic iron supplementation in the event of infection.


Iron, why is it important?

In case of moderate deficiency

Iron deficiency can manifest itself in the following problems. In this case a sufficient intake or even supplementation is necessary.

  • Anxiety
  • Hair loss
  • Constipation
  • Spasms
  • Fatigue
  • Brittle nails
  • Decrease in intellectual performance
  • Reduced physical performance
  • Coagulopathy
  • Numbness
  • Chilliness
  • Hyperemotionality
  • Soft nails
  • Chest tightness
  • Perleche (cheilitis)
  • Muscular weakness
In case of proven deficiency

A proven iron deficiency is involved in the following situations. The advice of a healthcare professional is required.

  • Infection
  • High dysphagia
  • Restless legs
  • Pica
  • Psychomotor delay
  • Iron deficiency anemia
In case of excess

Excess iron can lead to the following ailments, which is why it is not recommended to supplement with iron without the advice of a health professional. It is important to respect the recommended daily intake.

  • Shocks
  • Diarrhea
  • Fever
  • Digestive disorders
  • Jaundice
  • Vomiting
  • Hepatic insufficiency
  • Irritability
  • Metabolic acidosis
  • Convulsion
  • Abdominal pain
  • Hematemesis
  • Hemochromatosis
  • Hypoglycemia
  • Oxidative stress
Beneficial in prevention

Optimal iron intake helps prevent the following situations:

  • Fatigue
  • Iron deficiency anemia

Choose your foods wisely

  • Whole grains, not too many must : overall, fiber reduces the absorption of trace elements. However, the Western diet contains too little fiber to do without it. It is therefore advisable to opt for semi-complete cereals, the right balance to facilitate the absorption of iron, while satisfying our daily fiber needs.

Food preservation and storage

  • Fermentation or germination: iron is impacted by phytic acid, an anti-nutritional factor that reduces its absorption. However, sourdough fermentation of products from bread-making, and germination of seeds eliminates phytic acid. These actions promote iron absorption.

Preserving Iron in the kitchen

  • Homemade preparations: some processed foods contain preservatives EDTA (E385). This is the case for certain cold meats, emulsified sauces or even canned vegetables. This category of food additive plays an antioxidant function, so they ensure the stability of the products. However, EDTA interacts with metal ions, such as iron. We will therefore (always) prefer home cooking.

  • Soaking: the absorption of non-heme iron is further reduced by the presence of antinutrient factors (ANF): phytic acid and oxalic acid. They form non-absorbable complexes for the body. It is advisable to opt for pre-soaking legumes, oilseeds and seeds 12 to 24 hours before consumption. This soaking allows FAN to diffuse into the soaking water, increasing iron absorption. Note that it is preferable not to use this soaking water for cooking food if necessary: ​​cooking destroys oxalic acid, but not phytic acid, which will therefore return to the food if the soaking water soaking is used.

  • The cooking : oxalic acid and dietary fiber decrease iron absorption. Fiber is found in legumes, oilseeds, fruits, vegetables and whole grain products. For oxalic acid: coffee, tea, white wine, leafy vegetables, currants, mustard seeds and peanuts are rich in it. However, to our advantage, cooking destroys oxalic acid and denatures the fibers, which increases iron absorption.

  • Modified textures : fibers have the ability to limit iron absorption. Generally speaking, our diet is low in fiber. So, to combine these two facts, it is justified to reduce foods to juice, puree or even chopped texture. Because mechanical action denatures the fibers, which reduces their negative impact on iron absorption. For example, smoothies, gazpachos, soups, oilseed purees, hummus and other compotes are good alternatives.

Iron and interactions

Negative effects

  • Tannins: tannins are found mainly in tea (wines and coffee to a lesser extent). It is recommended to take these drinks 20 minutes before the meal, or 2 hours after the meal.

  • PPI medications: antacid treatments (proton pump inhibitors: PPIs) reduce gastric acidity. However, this acidity facilitates the absorption of non-heme iron.

  • Calcium: calcium competes with iron during intestinal absorption. Generally speaking, food sources of calcium have little influence on iron absorption. On the other hand, it is preferable to take a food supplement rich in calcium away from the meal, to minimize its influence on iron.

  • Chromium: chromium competes with iron. Indeed, they both bind to transferrin to be transported in the blood. It is therefore advisable to take a food supplement rich in chromium away from meals, to limit its impact on iron.

Positive effects

  • Vitamin C: the action of vitamin C concerns non-heme iron (from plants). Vitamin C has a reducing power, so it will facilitate the transformation of ferric iron into ferrous iron, improving its absorption. It is therefore wise to add foods rich in vitamin C (broccoli, peppers, citrus fruits, aromatic herbs, camu-camu or acerola) with foods rich in non-heme iron (legumes, cereals, dried fruits, etc. ...).

  • Gastric acidity: gastric acidity improves the absorption of non-heme iron. It is advisable to eat in a quiet place, to chew well and to take the necessary time, to promote the digestion process and therefore good gastric secretion.

  • Animal proteins: proteins, particularly those of animal origin (meat, fish, dairy products and eggs) seem to improve iron absorption. The mechanism of action is still little understood. In any case, the addition of ground meat to a Chili-con-carné is justifiable to improve the absorption of iron from red beans. Just like a mackerel spread on bread, improves the absorption of iron from bread.

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