IJzertekort? Dit is de oorzaak en zo vul je het aan

Iron deficiency? This is the cause and how to supplement it.

Geschreven door: Ebrina van der Bijl

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Leesduur: 9 min

When your body has too little iron, it can lead to fatigue, weakness and other unpleasant symptoms.

But what exactly causes an iron deficiency, and how can you replenish it? In this article, we'll delve deeper into the causes of iron deficiency and give you practical tips for replenishing your iron levels.

Iron deficiency occurs when there is insufficient iron for healthy red blood cells, causing symptoms such as fatigue, weakness and pallor.

Important causes include insufficient iron intake, reduced absorption, increased blood loss and greater needs (during menstruation, pregnancy, sports).

Supplementation can be done with iron-rich food (meat, legumes), vitamin C, supplements (iron bisglycinate) and healthy intestines for optimal iron absorption.

Table of contents
What is an iron deficiency? When do you have an iron deficiency? Symptoms and complaints of iron deficiency Types of iron deficiency Causes of iron deficiency 1. Insufficient iron intake 2. Reduced iron absorption 3. Increased iron loss 4. Increased iron requirement Iron deficiency due to menstruation How to quickly replenish iron deficiency: How to do it 1. Add more iron-rich foods to your diet 2. Check your diet for "iron absorption inhibitors" 3. Work on your intestinal health 4. Check your vitamin B12 level in your blood with your doctor Vitamin B12 and iron deficiency Top 5 best foods with iron Iron supplement

What is an iron deficiency?

An iron deficiency occurs when your body doesn't have enough iron to function properly. Iron is essential for producing healthy red blood cells, which transport oxygen throughout your body.

It is good to know that iron deficiency is not the same as anemia:

  • Iron deficiency means that you have too little iron in your body, which can lead to anemia.
  • Anemia is when your blood doesn't have enough healthy red blood cells, and iron deficiency is a common cause of this problem.

When do you have an iron deficiency?

If you ask your GP to test your iron levels, he or she will perform a combination of tests to get a complete picture of your iron status.

Serum iron measures the iron in your blood, but this is temporary and influenced by your diet or inflammation. Therefore, other tests are used to determine whether you have an iron deficiency (or anemia due to iron deficiency).

  • Hb (Hemoglobin) - Low at < 8.0 mmol/L (men) or < 7.5 mmol/L (women); indicates difficulty with oxygen transport, possibly due to iron deficiency.
  • Ferritin - Measures iron stores; a value below 15 micrograms indicates depleted iron stores (deficiency).
  • TSAT (Transferrin Saturation) - Low at <16%; indicates how much iron is being transported in your blood. A value below 16% may indicate a deficiency.
  • Total Iron Binding Capacity (TIB) - High at > 80 µmol/L; the body produces more transferrin in cases of iron deficiency. This value indicates how much transferrin is available to transport iron.

Symptoms and complaints of iron deficiency

Without enough iron, your body is less able to transport oxygen, which can lead to symptoms such as:

  • Fatigue - You feel tired quickly, even after enough sleep
  • Pale skin - Your skin, gums, and inner eyelids look pale
  • Shortness of breath - You get out of breath quickly, even with light exertion
  • Restless Legs - An uncomfortable feeling in the legs with an urge to move them

Types of iron deficiency

It is good to know that an iron deficiency can occur in two ways:

  • Absolute iron deficiency occurs when there is simply too little iron in the body. This can often be the result of blood loss, for example, after surgery or childbirth.
  • Functional iron deficiency means there's enough iron in the body, but it can't be used properly. This occurs when iron can't be released from the cells effectively. Inflammation can be the cause.

Causes of iron deficiency

There are several reasons why people may develop an iron deficiency:

1. Insufficient iron intake

Insufficient iron intake is common in:

  • People who eat few iron-rich foods , such as meat, legumes, and green leafy vegetables.
  • Vegetarians and vegans are at extra risk because plant-based iron (non-heme iron) is less well absorbed than iron from animal products (heme iron).
  • Elderly people often have a decreased appetite. This is one of the most common causes of iron deficiency in the elderly.

2. Reduced absorption

An iron deficiency can also occur if your body doesn't absorb iron properly, even if you're getting enough. This can happen, for example, in:

  • Bowel disorders such as celiac disease, Crohn's disease or chronic inflammatory bowel disease, which reduce absorption in the intestines.
  • Surgical procedures such as gastric reduction, which reduce the body's ability to absorb iron.
  • Medications , such as antacids, which can interfere with iron absorption. Reduced stomach acid production , which is more common in the elderly and is one of the causes of iron deficiency in the elderly.

3. Increased iron loss

Prolonged or excessive blood loss can lead to iron deficiency. Possible causes include:

  • Heavy or prolonged periods , a common cause in women.
  • Childbirth , during which a large amount of iron can be lost acutely.
  • Gastrointestinal disorders such as stomach ulcers, colon cancer and colitis, which cause blood loss.
  • Surgery, injuries, and blood donations , which lower iron levels.

4. Increased iron requirement

Some people have a higher iron requirement. This is especially true for:

  • Children and adolescents need more iron because they are growing.
  • Pregnant women need extra iron for the growth of the fetus and placenta.
  • Intense athletes lose iron through sweat and need more iron because of the increased muscle activity.
  • Older adults have higher iron needs due to various factors, including decreased appetite, lower stomach acid production, and increased risk of bleeding.

Iron deficiency due to menstruation

Menstruation is one of the most common causes of iron deficiency in women. This is because the body loses iron through blood loss.

The greater the blood loss, the higher the risk of iron deficiency.

  • Light periods - The body can often replenish iron loss through diet.
  • Heavy periods (menorrhagia) - The blood loss is so heavy that the body has difficulty replenishing enough iron, which can lead to a deficiency. (4)

How to quickly replenish iron deficiency

Do you often feel tired, listless, or dizzy? An iron deficiency could be the culprit.

Fortunately, you can quickly replenish your iron stores with the right nutrition and smart adjustments to your diet:

1. Add more iron-rich foods to your diet

The easiest way to replenish your iron deficiency is through your diet. Red meat , preferably grass-fed and organic, is the best source of iron because it contains the easily absorbable form (heme iron).

But if you don't eat any or very little meat, there are also plenty of plant-based options, such as spinach, pumpkin seeds and legumes.

These tips can help you supplement your iron:

  • Always combine this with vitamin C, for example from bell pepper, kiwi or orange, so that your body absorbs the iron better.
  • An iron supplement, such as Iron Premium , can be a good addition if you have difficulty getting enough iron from your diet.

2. Check your diet for "Iron absorption inhibitors"

Certain nutrients can inhibit iron absorption, such as calcium .

  • Therefore, don't take iron-rich foods or supplements directly with large amounts of dairy or calcium supplements. Ensure there's at least a two-hour gap between them.
  • When taking calcium supplements, choose the calcium citrate form, as this has less of an effect on absorption than calcium carbonate and calcium phosphate.

Beverages such as coffee, black tea, and some herbal teas (such as chamomile and peppermint) can also reduce the absorption of non-heme iron.

This is due to substances like chlorogenic acid in coffee, and catechins and theaflavins in tea, which bind to iron and make it harder for your body to absorb the iron.

  • To get the most out of your iron-rich meal, wait at least 1 to 2 hours before drinking coffee or tea.

3. Work on your gut health

Intestinal problems, such as disturbed intestinal flora or inflammation, can hinder the absorption of iron (8).

When there is inflammation in your intestines, your body produces more of the hormone hepcidin . This hormone inhibits the absorption of iron, making you more likely to develop an iron deficiency, even if you eat enough iron (9).

  • Therefore, ensure you eat a balanced diet with probiotics and fibre to support your intestines.
  • In case of intestinal inflammation, it is best to discuss with your doctor what approach is right for you.

4. Check your vitamin B12 level in your blood through your GP

A vitamin B12 deficiency can cause iron to function less effectively in your body, and conversely, an iron deficiency can also affect your B12 levels.

  • It is therefore wise to have your vitamin B12 levels checked by a blood test at your GP, so that you can address any deficiency in a timely manner.

Vitamin B12 and iron deficiency

Both vitamin B12 and iron are important for the production of healthy red blood cells. A vitamin B12 deficiency can prevent your blood cells from maturing properly and causing them to die more quickly, leading to anemia.

On the other hand, an iron deficiency can also lead to reduced red blood cell production, because iron is needed to transport oxygen in the blood.

The problem is that a vitamin B12 deficiency can hinder the absorption and utilization of iron, making you more likely to develop an iron deficiency. Both deficiencies can therefore reinforce each other and make it more difficult to produce healthy blood. (10)

Top 5 Best Foods with Iron

The best and easiest way to prevent a deficiency is to eat more iron-rich foods.

This is the best food to eat to get more iron:

1. Beef liver - 8.1 mg iron per 100 gram serving

  • 51% of the RDA (women aged 14 and over)
  • 74% of the RDA (postmenopausal women and men aged 9 and over)

2. Grass-fed beef (Organic) - 2.75 mg iron per 100 gram serving

  • 17% of the RDA (women aged 14 and over)
  • 25% of the RDA (postmenopausal women and men aged 9 and over)

3. Spinach - 4 mg iron per 200 gram serving

  • 25% of the RDA (women aged 14 and over)
  • 36% of the RDA (postmenopausal women and men aged 9 and over)

4. Oatmeal - 3 mg iron per 75 gram serving

  • 19% of the RDA (women aged 14 and over)
  • 27% of the RDA (postmenopausal women and men aged 9 and over)

5. Pumpkin seeds - 2 mg per 25 gram serving

  • 13% of the RDA (women aged 14 and over)
  • 18% of the RDA (postmenopausal women and men aged 9 and over)

Iron supplement

If you have a severe iron deficiency or don't eat meat, an iron supplement may be a good solution.

Preferably choose iron bisglycinate , as this is the most absorbable form of iron. Ensure the supplement contains a safe but effective amount of iron, ideally between 11 and 45 mg per dose.

Our Iron Premium tablets contain this ideal dosage and are enriched with natural vitamin C , which helps your body to absorb the iron even better.

Ebrina van der Bijl - Natural Performance

Ebrina van der Bijl

Ebrina is a nutritionist with a deep commitment to healthy eating and a sustainable lifestyle, based in beautiful Portugal. Her passion for natural and organic products is at the heart of her work. With a background in Nutrition & Dietetics and experience in product development and writing, she translates complex scientific information into practical advice for a balanced lifestyle.

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Sources used

  1. World Health Organization: WHO & World Health Organization: WHO. (2025, February 10). Anemia. https://www.who.int/news-room/fact-sheets/detail/anaemia
  2. Kumar, A., Sharma, E., Marley, A., Samaan, M.A., & Brookes, M.J. (2022b). Iron deficiency anemia: pathophysiology, assessment, practical management. BMJ Open Gastroenterology, 9(1), e000759. https://doi.org/10.1136/bmjgast-2021-000759
  3. World Health Organization & International Micronutrient Malnutrition Prevention and Control Program of the United States Centers for Disease Control and Prevention. (2021). NEW THRESHOLDS FOR THE USE OF FERRITIN CONCENTRATIONS TO ASSESS IRON STATUS IN INDIVIDUALS AND POPULATIONS. https://www.who.int/docs/default-source/micronutrients/ferritin-guideline/ferritin-guidelines-brochure.pdf?sfvrsn=76a71b5a_4
  4. Mansour, D., Hofmann, A., & Gemzell-Danielsson, K. (2020). A Review of Clinical Guidelines on the Management of Iron Deficiency and Iron-Deficiency Anemia in Women with Heavy Menstrual Bleeding. Advances in Therapy , 38 (1), 201–225. https://doi.org/10.1007/s12325-020-01564-y
  5. Dutch Healthcare Institute. (n.d.). Calcium carbonate (as a supplement). https://www.farmacotherapeutischkompas.nl/bladeren/preparaatteksten/c/calciumvezel__als_supplement_
  6. Hurrell, R. F., Reddy, M., & Cook, J. D. (1999). Inhibition of non-haem iron absorption in man by polyphenolic-containing beverages. British Journal Of Nutrition, 81(4), 289–295. https://doi.org/10.1017/s0007114599000537
  7. Morck, T., Lynch, S., & Cook, J. (1983). Inhibition of food iron absorption by coffee. American Journal Of Clinical Nutrition, 37(3), 416–420. https://doi.org/10.1093/ajcn/37.3.416
  8. Loveikyte, R., Bourgonje, A., Van Goor, H., Dijkstra, G., & Van Der Meulen – de Jong, A. (2023). The effect of iron therapy on oxidative stress and intestinal microbiota in inflammatory bowel diseases: A review on the conundrum. Redox Biology, 68, 102950. https://doi.org/10.1016/j.redox.2023.102950
  9. Loveikyte, R., Bourgonje, AR, Van Der Reijden, JJ, Bulthuis, MLC, Hawinkels, LJAC, Visschedijk, MC, Festen, EAM, Van Dullemen, HM, Weersma, RK, Van Goor, H., Van Der Meulen-De Jong, AE, & Dijkstra, G. (2023). Hepcidin and Iron Status in Patients With Inflammatory Bowel Disease Undergoing Induction Therapy With Vedolizumab or Infliximab. Inflammatory Bowel Diseases, 29(8), 1272–1284. https://doi.org/10.1093/ibd/izad010
  10. Vitamin B12–Deficiency Anemia | NHLBI, NIH. (2022, March 24). NHLBI, NIH. https://www.nhlbi.nih.gov/health/anemia/vitamin-b12-deficiency-anemia
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