Definition of iron deficiency

It is important to distinguish between iron deficiency and anemia. Iron deficiency is characterized by a depletion of the body's iron stores, without indicating the degree of depletion or the presence of anemia. An individual can have an iron deficiency without being anemic. However, iron deficiency remains a common cause of anemia, a condition where the body's iron stores are very low. Iron deficiency is also one of the most common deficiencies worldwide.

Etiology of iron deficiency

In adults, iron deficiency is generally due to blood loss, such as heavy menstrual bleeding or hemorrhage in the digestive tract. It can also be caused by certain digestive diseases that lead to malabsorption, such as celiac diseaseFinally, iron deficiency can also be due to inadequate nutrition, especially in children and pregnant women who have increased iron needs.

Iron Deficiency Symptoms

When the body's iron stores are severely depleted, iron deficiency anemia, also called iron-deficiency anemia, occurs. Symptoms of anemia may include fatigue, weakness, paleness, difficulty concentrating and learning. Severe anemia can also cause an increased heart rate, dizziness, difficulty breathing, and absence of menstruation.

Iron Deficiency Diagnosis

The diagnosis of iron deficiency is generally made based on the symptoms present and the results of blood tests. During the diagnosis, it is also important to differentiate anemia caused by iron deficiency from other types of anemia. Anemia due to iron deficiency is characterized by abnormally small and pale red blood cells.

Iron Deficiency Treatment

When iron deficiency is caused by bleeding, treatment involves controlling the bleeding. Treatment may also include taking medication, dietary supplements and rarely intravenous iron administration. When iron deficiency is due to inadequate dietary intake, taking an iron supplement and making nutritional changes can help treat it.

Nutritional approach for iron deficiency

The nutritional approach generally includes increasing the consumption of iron-rich foods. A healthcare professional may also prescribe an iron supplement.

Iron in the diet

Iron is a mineral naturally found in several foods. There are two types of iron: heme iron and non-heme iron. Heme iron is found in animal-based foods such as meat, fish, and seafood. Non-heme iron is mainly present in plant-based foods, such as legumes, nuts, seeds, enriched grains (e.g., pasta), soy-based products (e.g., tofu, tempeh, fortified soy beverages), and certain vegetables (e.g., dark green leafy vegetables). Heme iron is better absorbed by the body than non-heme iron, which accounts for about 85% of iron intake in an average diet.

Substances that limit the absorption of non-heme iron

Certain substances present in foods interfere with the absorption of non-heme iron. These substances bind to non-heme iron and prevent its absorption. This is notably the case with phytates found in legumes, whole grains, and nuts, calcium present in milk, as well as certain polyphenols found in tea and coffee. For individuals with iron deficiency, it is therefore preferable to consume tea or coffee at least 30 minutes before or after meals containing a source of non-heme iron.

Increase the absorption of non-heme iron

There are two ways to increase the absorption of non-heme iron by the body. The first is to combine a source of non-heme iron with a source of vitamin C, which is mainly found in vegetables and fruits. For example, you can drizzle spinach with a splash of lemon juice or serve a pasta salad with tomatoes. The second way to increase the absorption of non-heme iron is to pair it with animal-based proteins. For example, you can combine red beans and ground meat in a chili.  

Daily iron requirements for adults

Heme iron sources

Heme iron is found in animal-based foods such as:

• Meat (e.g., beef, pork, lamb)
• Poultry (e.g., chicken, turkey)
• Fish (e.g., trout, tuna, sardines)
• Seafood (e.g., shrimp, scallops, mussels, oysters)
• Offal (e.g., liver, kidneys)

Non-heme iron sources

Non-heme iron is mainly found in plant-based foods such as:

• Legumes (e.g., green lentils, chickpeas, white beans)
• Nuts and nut butters (e.g., peanuts, almonds, pistachios)
• Seeds and seed butters (e.g., pumpkin, sunflower)
• Some vegetables (e.g., asparagus, broccoli, spinach)
• Grains and enriched grains (e.g., wheat, bread, pasta)
• Dried fruits (e.g., raisins, prunes, dates, apricots)
• Soy-based products (e.g., extra firm tofu, tempeh, fortified soy beverages)
• Molasses
• Yeast extract-based spreads (e.g., Marmite, Vegemite)

References

1. https://www.unlockfood.ca/en/Articles/Iron/Managing-iron-deficiency.aspx
2. https://www.merckmanuals.com/en-ca/professional/nutritional-disorders/mineral-deficiency-and-mineral-toxicity/iron-deficiency#:~:text=In%20addition%20to%20anemia%2C%20iron%20deficiency,post-cricoid%20esophageal%20diaphragm.
3. https://www.merckmanuals.com/en-ca/home/disorders-of-nutrition/minerals/iron-deficiency?query=Iron%20deficiency
4. Understanding Nutrition, by Eleanor N. Whitney et al., Nelson Education, 2013, pp. 443–451.
5. https://www.canada.ca/en/health-canada/services/nutrients/iron.html
6. https://www.mcgill.ca/oss/article/can-coffee-inhibit-absorption-iron

Article written by:

Marie-Noël Marsan, Nutritionist