Iron deficiency: symptoms, effects and treatment

It is a topic that comes up often: iron deficiency is indeed the most common nutritional deficiency in women at all stages of life. Iron is a mineral essential to our well-being, as it participates in the production of red blood cells and the proper functioning of bone marrow. Requirements vary according to life stages—puberty, childbearing years, pregnancy, perimenopause—for reasons that are not always the same. We explain where this deficiency comes from, how to recognize it, and how to correct it.

What is the role of iron in the human body?

Iron plays a crucial role in the proper functioning of our body, especially in pregnant women.

Why do we need iron?

Without iron, the body cannot produce enough healthy red blood cells. This mineral plays an essential role in:

• transporting oxygen throughout the body;
• converting nutrients into energy.

During pregnancy, iron becomes even more important: it supports the development of the fetus and the placenta, and helps cover the increase in maternal blood volume.

How much iron do we need?

According to ANSES, iron requirements differ according to sex and life stages:

• approximately 11 mg/day for men and for postmenopausal women or those with low menstrual blood loss;
• approximately 16 mg/day for women with heavy periods, or those who are pregnant or breastfeeding.

Good to know: a normal diet provides between 10 and 15 mg of iron per day, of which only about 5 to 10% will be absorbed by the body.

Iron deficiency: what are the symptoms?

An iron deficiency can manifest through various symptoms:

• persistent fatigue that does not go away with rest;
• pale skin and mucous membranes (revealing a low hemoglobin level);
• shortness of breath, even after light exertion;
• a faster heart rate (the body compensates for the lack of oxygen);
• feelings of dizziness.

In some people, iron deficiency can also lead to:

• brittle nails;
• hair loss;
• headaches.

These symptoms can be more concerning for pregnant women, as they involve both their own health and that of their unborn child.

How to diagnose an iron deficiency?

To diagnose an iron deficiency, your doctor will generally prescribe a clinical assessment with a specific blood test to measure various indicators related to your iron levels.

This assessment measures several elements, including hemoglobin content (a low level may indicate iron deficiency), as well as ferritin or serum ferritin levels.

If these indicators are low, it confirms that iron stores are depleted. Your doctor will then be able to recommend the most appropriate treatment.

What are the most common causes of iron deficiency?

Common causes in women

One of the most common causes of iron deficiency in women between puberty and menopause is heavy periods. If blood loss is particularly intense, diet becomes an insufficient source of iron to compensate, leaving the body with empty reserves.

Diet alone may also no longer be enough to compensate for the lack of iron. Iron from animal sources is better absorbed by the body than iron from plant sources: if you follow a vegetarian diet, it is therefore useful to plan it carefully to avoid deficits.

Causes specific to pregnancy

Pregnancy leads to a significant increase in iron requirements, necessary for the development of the fetus and the placenta, as well as for the increase in the mother's red blood cell volume. It is therefore important to ensure sufficient intake via a rich and varied diet, at the risk of developing a more pronounced deficiency.

Iron requirements evolve throughout life

Iron deficiency is not just about pregnancy: requirements and risks vary according to the major stages of a woman's life.

During adolescence

Iron requirements increase with growth and the onset of menstruation. A monotonous diet or absorption disorders can favor a deficiency during this period; this is a point to monitor with a healthcare professional in case of unusual fatigue or heavy periods.

During childbearing years

Between puberty and menopause, women have higher iron requirements than men of the same age, mainly due to losses related to menstruation. Heavy periods are one of the most common causes of iron deficiency in women of childbearing age.

Other risk factors to be aware of

Beyond life stages, certain factors can increase the risk of iron deficiency at any age:

• Heavy or prolonged periods (menorrhagia): beyond a certain threshold of bleeding, iron loss is no longer compensated by diet alone. Note: unlike the hormonal IUD (which tends to lighten or even stop periods), the copper IUD, which is hormone-free, can on the contrary be associated with heavier periods in some women, especially in the first year.
• Intense physical activity: practicing an endurance sport regularly can increase iron loss (digestive micro-bleeding, destruction of red blood cells due to repeated impacts, sweating).
• Regular blood donations: each donation leads to an iron loss that the body must replenish, which may justify monitoring in regular donors.
• Certain digestive disorders: celiac disease, inflammatory bowel disease (IBD), or the aftermath of bariatric surgery can reduce iron absorption in the intestine, regardless of dietary intake.
• A restrictive or monotonous diet: vegetarian, vegan, or simply low in sources of iron, over a prolonged period.

If you recognize yourself in several of these situations, do not hesitate to talk to your doctor, who will be able to determine the relevance of a blood test.

During perimenopause

This transition phase, which can last several years before menstruation stops completely, is often accompanied by irregular cycles and sometimes heavier bleeding. Hormonal fluctuations (drop in estrogen) can also make iron absorption slightly less efficient. It is therefore a period where vigilance remains necessary, especially in the case of very heavy periods.

After menopause

Once periods have stopped, iron requirements decrease and become closer to those of men (about 11 mg/day). Iron deficiency then becomes much less common. Conversely, it is rather an excess of iron (hyperferritinemia) that should be monitored at this stage of life, as the body no longer has regular menstrual losses to eliminate excess iron. This is why iron supplementation is not recommended by default after menopause, unless a deficiency is confirmed by a blood test.

How to treat an iron deficiency?

By adopting an iron-rich diet

To increase your iron intake, favor animal-based products such as:

• red meat;
• poultry;
• fish.

Are you vegetarian? There are also many plant-based sources of iron:

• legumes (lentils, chickpeas, beans, etc.);
• nuts;
• dark chocolate;
• green leafy vegetables.

Always pair these foods with sources of vitamin C, which increases iron absorption.

With supplements

If your diet is not enough to compensate for the iron deficiency, your doctor may possibly recommend supplementation. Many pregnant women, however, find it difficult to follow their treatment to the end because some iron tablets can cause digestive problems (stomach aches, constipation)—even though the risk of anemia is often highest at the end of pregnancy. This is why it is important to maintain sufficient iron reserves throughout pregnancy, in consultation with your doctor or midwife, who can direct you to a more tolerable form of iron if necessary.

There are indeed different forms of iron available for supplementation. Ferrous sulfate is the most commonly used form, but other forms such as iron bisglycinate exist and are being studied for their digestive tolerance. A randomized study conducted on 80 Danish pregnant women (Milman et al., 2014), for example, showed that at half-dose (25 mg vs. 50 mg of elemental iron), bisglycinate allowed for the maintenance of iron status equivalent to ferrous sulfate, with reported good digestive tolerance. Do not hesitate to discuss with your doctor or pharmacist which form is best suited to your situation.

Intravenously

In cases of severe anemia or when oral supplements are not well tolerated, intravenous supplementation may be considered. This method allows for a rapid increase in ferritin levels in the body. It is generally reserved for situations where intestinal absorption is compromised, or when iron stores need to be reconstituted rapidly, particularly when preparing for surgery.

Iron deficiency, while common, is not inevitable: with an adapted diet and, if necessary, medical follow-up, it can be effectively corrected, regardless of the stage of life in which it occurs.

Are you pregnant and wondering if your fatigue could actually be linked to anemia? Our article Pregnancy anemia: why and how to avoid it details the diagnosis and treatment of this condition.

Are you pregnant and don't know where to start in terms of vitamins? Discover how to properly choose your pregnancy vitamins.

This article is written for information purposes and does not constitute medical advice. Only a healthcare professional can diagnose an iron deficiency and determine the treatment adapted to your situation.